Icom 706 -- Major Defect Found!

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Icom 706 -- Major Defect Found!

G.M. (WA6CDE) on November 4, 2005
View comments about this article!

Icom 706 Mk has a major problem... design flaw .... be careful out there...

I recently have run into two other hams who now have had the same failure with their ICOM 706s' ... both have be scraped due to the bad service that ICOM has been promoting on this issue...

It appear that the Caps C188 and C604 both are rated for 16 volts at 1000uf... these are electric caps and as such have liquid in them which is corrosive... and currently the way that ICOM instructs you to wire the radio up for mobile operation can lead to the failure of one or more of these caps... which can do irreparable damage to your 706 if they burst or catch fire by shorting out in the process of their explosion...

Here is why....

The instruction manual says to hook the leads of the 706 directly to the battery... make a good connection... as it says that can handle at least 30 amps... fine..

However, when you check the shop manual circuit diagram... it shows that the power is ever present on the input to the radio.. and also the PA amp section that these little caps are associated with.

Why did they do this.... well ICOM being cheap didn't want to switch the high current PA section on and off... by putting some device in that would handle 30 amps... so what they did was wire it so that the finals are hot all the time as a direct connection (see drawing) and its associated circuitry of which these two caps are in line with.

So what's the beef...

Well if you go starting the car... your starter can develop spikes that amount to several times the input voltage... thus the little caps which are rated at 16 volts are right at what the battery voltage and charging system is... So when you go to start the car you could be placing at least 2 to 3 time (30-45 volts) of the battery voltage across them.. thus, we have exceeded the voltage rating of the caps... some one at ICOM didn't quite figure that out right... I would think...

What is also amazing on this radio is that someone has not had one of the PA transistor fail and cause a fire or at the least flatten the battery while it is un-attended... if they failed also... something not to be taken lightly...

When we called ICOM... not once but 4 times now to present this design flaw to them and to see if they will back the defective material or part... due to their under sight.. we were told that for 90 bux an hour they would fix it... (1 hr MIN) plus the shipping to and from can become a expensive issue...

So what's the fix...

Well about the only thing that you can do is to put either a relay or a ckt breaker in series with the power leads going to the 706... Sure its going to be costly.. but, how much is your car worth... or the radio... as it appears that ICOM is reluctant to fix the bad capacitors when they fail... which then could lead to the radio becoming a boat anchor eventually...

I know K0BG is going to differ with me on this but, I prefer that a aviation toggle switch circuit breaker (such as what can be gotten from Chief Aircraft parts) be put in the positive feed line... Here you can have a selection of a toggle switch or a rocker switch similar to what aircraft call the avionics master switch... that does about the same as what you need to do in the car... and that is remove the power from the radio until after you start the car... and the charging system has settled down.

It is the only way that you will be able to isolate the 706 from the rest of the electrical system... as their on/off button on the front does not remove or apply power to the PA board as shown.

I am against using a dual relay contactor as the points of the relay will eventually develop some IR drop and again your going to suffer the effects of a low voltage application... and cleaning the contact is some what of a chore. While the good quality 30+ circuit breaker that has the regular toggle switch on it was made for the aircraft environment and thus can stand the test of time without having problems...

Conclusion

If you own a ICOM 706 and don't make the modifications to the power input leads... you can stand a chance of damaging the radio due to their deficiencies and/or loss of electrical to the car leaving you stranded or thinking that the battery is no good... worst yet... come back and find it had a color change as it burnt up... if the 30 amp fuses don't work as advertised...

I am sure a lot of people who own a ICOM 706 are not aware of the design deficiency and the fact that if it happens your going to have to pay for it.... thus we call it to your attention... as I am sure ICOM would never...

0x01 graphic

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Icom 706 -- Major Defect Found!

by G4IJE on November 4, 2005 Mail this to a friend!

Hmmm... there are an awful lot of IC-706s operating mobile every day and if this was a major problem I would have thought we would have heard more about it by now. Doesn't connecting directly to the battery help to PREVENT voltage spikes? The battery acts as an enourmous capacitor; maybe someone who knows more about auto electrics would like to comment.

>>ICOM being cheap didn't want to switch the high current PA section on and off..

Isn't that fairly standard practice?

73, Paul G4IJE.

RE: Icom 706 -- Major Defect Found!

by N7BUI on November 4, 2005 Mail this to a friend!

This has been standard practice from manufacturers for many many years. The battery is the most stable source of voltage in a vehicle and that is why Icom recommends attaching the power leads directly to it. One of it's other jobs is to act as a voltage stablizer in the electrical system and to absorb voltage spikes. If you are seeing 35-40 volt spikes in the system, it's probably not doing its job and is beginning to get weak. I have seen many cases of "whine" in public safety radios that have been solved simply by having the vehicles battery replaced.

RE: Icom 706 -- Major Defect Found!

by N8NOE on November 4, 2005 Mail this to a friend!

I have connected my 706MkIIg to the Car, in the Shack and Now in the BackPack.. NEVER had any trouble like this?.. As for the CAPS, Sony has this type issue with the SW-1's and radios of this vintage. I have replaced MANY now here, and Understand the trouble. Seesm these were "State of the Art" at the time all the design and about the time the 706 came out.. If it hasn't got to eating the Board, it's not a bad fix, if it eats at the board you got a mess and a world of trouble.. I have the 706MkIIg and the 746PRO and after ALL the radios, I'm VERY happy using Icom's.. I hope you get your all good, but I'm with the Second post, Seems we'd hear more if this was a Big Issue..

Icom 706 -- Major Defect Found!

by ARRLBOOSTER on November 4, 2005 Mail this to a friend!

This article is just a wrong headed flame against a fine company and a workhorse of a product. I laughed when I read the sensationalistic headline. Thank you, Einstein.
Ric

RE: Icom 706 -- Major Defect Found!

by W8JI on November 4, 2005 Mail this to a friend!

There is nothing wrong with connecting across the battery and leaving the PA energized, assuming the PA is stable and the system fused.

I'm not sure placing 16V rated caps across a battery input is the best idea, since many electical systems go over 15 volts. Reliability depends a great deal on the design headroom of the capacitor itself. Electrolytics can be a mess.

Looks to me like a cheap and simple fix would be using commonly available 35 volt capacitors. Looks like more of a component selection issue than a design issue.

73 Tom

Icom 706 -- Major Defect Found!

by W1FBI on November 4, 2005 Mail this to a friend!

I run Icom 706 in my mobil. Cole-Hersee Mfg. Of Boston,Ma. Part# 2484-06 sells A battery Disc. switch.
Rated: 6-36 vdc 175Amps. CONTINUOUS {1000 Amp Intermittent}.This switch can be used to cut the
power to the radio OR The electrical system of the car.

Ed W1FBI

RE: Icom 706 -- Major Defect Found!

by K8MHZ on November 4, 2005 Mail this to a friend!

"So when you go to start the car you could be placing at least 2 to 3 time (30-45 volts) of the battery voltage across them.."

How so? Your battery can only provide 12 volts and that drops to 10 or 11 while cranking the engine. Where do the rest of the volts come from?

73,

Mark K8MHZ

Icom 706 -- Major Defect Found!

by NE0P on November 4, 2005 Mail this to a friend!

What about the other major design flaw in the 706MKIIG-it's receiver sucks!! The 706 original has a better receiver in it.

Icom 706 -- Major Defect Found!

by KB7LYM on November 4, 2005 Mail this to a friend!

Never had any problem with my ICOM-706 ! But there are those that have a gripe against this company or that one and getting their kicks picking fuzz from their navels and complaining and then writing all that stuff down to get support from the masses to bolster their ego with all that knowledge they present. Just an old f__t doing swimming up river with an anvil around his neck. Relax folks.... who knows the next item might be the ICOM IC-756PRO for 12000 greenbacks. Just get your hammer ready in case you get an advise from the problem solver. Aye !!!! ICOM-706 still working !!

Icom 706 -- Major Defect Found!

by WA2DYA on November 4, 2005 Mail this to a friend!

Does anyone know what the voltage accross these capacitors is when the amplifier is amplifying?

--- CHAS

RE: Icom 706 -- Major Defect Found!

by AA4PB on November 4, 2005 Mail this to a friend!

Where do the rest of the volts come from?
------------------------------------------
The inductance of the windings in the starter motor often causes some rather sizable voltage spikes during starting. It is common practice to consider these spikes during design of automotive equipment.

I notice that the 706 has two diodes directly across the input. I wonder if these might be of the surge protection type that prevents these spikes from appearing on the internal DC lines.

Icom 706 -- Major Defect Found!

by K2JVI on November 4, 2005 Mail this to a friend!

Re:Does anyone know what the voltage accross these capacitors is when the amplifier is amplifying?

--- CHAS

By looking at the schematic,I would suspect the voltage to be no more than the nominal voltage bieng fed to the radio,and somewhat less(not by much)when the amp.is on. I would NOT expect to see this voltage increase with the amplifier on.

73's.

RE: Icom 706 -- Major Defect Found!

by KK4BH on November 4, 2005 Mail this to a friend!

by G4IJE on November 4, 2005
Hmmm... there are an awful lot of IC-706s operating mobile every day and if this was a major problem I would have thought we would have heard more about it by now. Doesn't connecting directly to the battery help to PREVENT voltage spikes? The battery acts as an enourmous capacitor; maybe someone who knows more about auto electrics would like to comment.

Exactly! You can run a radio off of a car battery that is being charged by a pulsating DC source, such as a battery charger, and have the purist most regulated DC voltage present at your radio. The closer you connect the radio across the battery the less ripple and spikes will be present. This is one reason it is not advised to use the cigar lighter. The maze of wiring further removes the radio from the filtering effects of the battery and can increase the chance of spikes being present. Also, the path from the accessory wiring may not be as direct a path as you think. Relays, fusable links and solid state switches run rampid in automobile wiring. It is possible for a momentary break to the battery, allowing the radio to "feel" the unregulated, unfilterd charging voltage. This is rare but could happen.

I owned a 706MK2 for over 2 years and have presently owned a 706MK2G for over a year. They are powered in the shack by a Astron RS35M and left on 24/7. They have weathered numerous power failures, not being damaged by the power surge when the power comes back on.

The 706 series is probably one of if not the most popular HF mobile radio. If this were a cronic problem I think we'd be hearing alot more of it. I believe this condition is either a rare random failure or due to not connecting the radio properly in the car/ failure of automobile wiring.

73
KK4BH
Ken

RE: Icom 706 -- Major Defect Found!

by K3WVU on November 4, 2005 Mail this to a friend!

Never had a hint of problems with my 706MKIIG, and have never heard anyone else complain about it, either.

Dwight K3WVU

RE: Icom 706 -- Major Defect Found!

by NJ2L on November 4, 2005 Mail this to a friend!

Those diodes prevent reversing the supply polarity by presenting a short and popping the line fuse.

My understanding of capacitors is that the most stress on a capacitor and the supply sorce is when they are first enegized. This would make me think that adding a switch inline with the supply will now increase the number of times these capacitors need to charge from zero volts, thus stressing the capacitors more. I have noticed a small spark when reconnecting the 706 back into the car. I would rather avoid this surge to the capacitors than letting them sit at a level voltage most of the time.

RE: Icom 706 -- Major Defect Found!

by K0BG on November 4, 2005 Mail this to a friend!

I saw this article about the same time it was posted on eham.net. And yes, I disagree with some of the premise. And I disagree with some of the solutions posted herein as well.

As has been mentioned in at least three posts, if this were indeed a problem, every single one of us would know about it. The Icom 706 in its various configurations, commands a 75% share of the world-wide mobile marketplace. With these numbers in mind, even if 1,000 units had failed due to this purported problem, from a statistical standpoint, this is a minute number. I would further suggest that if they do fail, it is a problem with the electrical system in the vehicle, not one in the design of the Icom.

The published voltage spec for the 706 is 13.8 VDC ± 15%. Unless my math is defective, that's a maximum of 15.87 VDC. If your vehicle's voltage is this high, you're going to have a lot more problems than just your 706.

Adding power relays in series with mobile transceivers is a questionable practice. As a result of the information published on my web site, I've heard just about every argument pro and con. The only one that makes sense is to offer a solution to those who can't remember to turn off their radios. Well, a 706 has a built in auto off feature, so (thanks to Yoda) out the window that argument goes!

Alan, KØBG
www.k0bg.com

RE: Icom 706 -- Major Defect Found!

by K6LCS on November 4, 2005 Mail this to a friend!

>>...just a flame against a fine company and a workhorse of a product. I laughed...

If there was a widespread problem with this unit, it has escaped my employer - arguably Icom's largest dealer in North America. Of the last 1,000 IC-706MKIIG we have sold, there have been an extremely small number of total warranty repair submissions...a number so small that it's well within anyone's "confidence level" for such a product.

Clint Bradford, K6LCS

RE: Icom 706 -- Major Defect Found!

by NI0C on November 4, 2005 Mail this to a friend!

W8JI said:
"Looks to me like a cheap and simple fix would be using commonly available 35 volt capacitors. Looks like more of a component selection issue than a design issue."

When I was doing circuit design, component selection was an integral part of my job. So was making sure there was plenty of "headroom" in the component ratings.

73,
Chuck NI0C

Major Defect Found in Ham expectations!

by W9WHE-II on November 4, 2005 Mail this to a friend!

Hams...they complain about the high price...then complain about the simple design required to keep the price down to what they want to pay.

If you want a higher qualify HF mobile, and are willing to pay the price, ....then buy a Motorola Micom. If you want a lower cost radio, buy an Icom. But don't expect Motorola design quality at an Icom price!

W9WHE

Icom 706 -- Major Defect Found!

by WQ1H on November 4, 2005 Mail this to a friend!

Interesting: I have used the 706 mobile from the day it was first sold. Not a problem. I have owned all three models.

Then like most of use we do not read the manual. Under precautions...Make sure the tranceiver power is OFF before starting the vehicle. This will avoid possible damage to the transceiver by ignition voltage spikes.

I have made a few violations of this precaution...WHOOPS. No failure...the components can handle certain amounts of excess...good design.

Abuse of design limitations is not a defect. Light up a bulb rated for 110 with 220. It is bright for a moment...

Dave

RE: Icom 706 -- Major Defect Found!

by K5LXP on November 4, 2005 Mail this to a friend!

Once something hits production, cost reduction becomes the overriding priority. A bean counter sits down with a reliability engineer and determines that 16V caps would take the unit beyond the warranty period, so that's what's used. Considering the number of units that have failed for this 'problem', I'd say they were right. It's a big tradeoff between cost and MBTF, if you design the max margin into every part the product would become unaffordable.

To the author of the article, having some data or evidence to support the statement of 'a major problem' would go a long way to establishing the legitimacy of the claim. 'Two other hams' compared to the many tens of thousands of units out there accounts more for a random bad cap than a design flaw. Add in the myriad of variables that existed surrounding the failed units (actual connections, temperature, number of cycles, etc) and it indicates anything *but* a design problem.

Mark K5LXP
Albuquerque, NM

RE: Icom 706 -- Major Defect Found!

by VE2LH on November 4, 2005 Mail this to a friend!

Assuming that these capacitors are tantalum, good design practices are 1) presence of a series resistor in order to limit the surge current (not always easy to implement). 2) A minimum voltage derating of 50%.

Beware that overheating (even slightly) the capacitor while repairing will have a very important impact on the part life.

I would recommend replacing the part by a higher voltage one. (Design rule here : 100% derating)
73

Icom 706 -- Major Defect Found!

by KB1GMX on November 4, 2005 Mail this to a friend!

Find a radio where those caps are rated for more than
16V. When you do let us know. It will be rare.

Further that 16V is working voltage, nearly all of those parts if you look them up have a peak surge that is higher. If you exceed the 16V what happens? How long did that peak voltage have to stand (as a constant voltage) before failure occurs? I've seen real cases
of wrong caps run for hundreds to thousands of hours at +150% (continious) before failing.

Last item, if your exceeding those by the stated amounts
the finals will likely see overvoltage and fail.

Sorry, the sky is not falling.

Just make sure you hook up correctly to the battery
and fuse both hot and ground.

If it were such a problem you'd see reports. can you find any?

Allison
Kb1GMX

RE: Icom 706 -- Major Defect Found!

by WA9SVD on November 4, 2005 Mail this to a friend!

Isn't it "Good Amateur Practice" as well as good electrical and common sense to fuse ANYTHING connected to the battery?
Almost every manual tells you to fuse the device AT THE BATTERY. (Although there are differing opinions about whether the negative lead should also be connected to the battery, but if it is, it should also be fused!)
A fuse will protect the radio, the car, the wiring, AND the battery.

Icom 706 -- Major Defect Found!

by WA0ZZG on November 4, 2005 Mail this to a friend!

Sorry you are having problems with your radio. I don't
think it happens that often. The voltage spike, you
talked about is from the inductive kickback from the
starter. The battery will act like a large filter
cap to smooth it out. That's why ICOM recommends
a connection directly to the battery. Having the
PA stage wired directly to the battery is a normal
design these days. Most radios have a soft start
power switch. I've not seen this to be a problem with
Amateur equipment. I have seen problems with commercial
radios though. This is because type acceptance procedures do not require testing with the power off.
I've seen PA's break into oscillation when the radio
is turned off. Fun thing to find, which truck is
spitting out RF.
Dave WA0ZZG

RE: Icom 706 -- Major Defect Found!

by KC8VWM on November 4, 2005 Mail this to a friend!

... I figure by the time this thread is all said done we will have completely redesigned the Icom 706, drawn a new schematic, and have a built in vibroplex key sticking out of the faceplate.

73 Charles - KC8VWM

Icom 706 -- Major Defect Found!

by WA1RNE on November 4, 2005 Mail this to a friend!

The automotive electrical system can be a very hostile environment for electronic devices like amateur gear and audio equipment.

There are a couple of ways that the nominal 12-14 vdc electrical bus can become much higher and cause damage to equipment:

1) A load dump where the battery becomes disconnected and the charging system is running at a high charge rate. Under these conditions, the electrical system can see transients as high as 25-125 vdc for up to several hundred milliseconds. Not a good idea to disconnect your battery while the vehicle is running....

2) A failed voltage regulator. This can result in steady state overvoltage of up to 18 vdc.

3) In some instances, jump starting can produce as high as 24 vdc depending upon the state of the battery being jumped and the type of equipment creating the "jump".

4) Inductive load switching. Vehicles have countless numbers of relays, as well as the ignition system inductors (coils) that can create transients as high as 300 vdc for ~300 microseconds or less in duration.

One of the ways to protect against these conditions is to specify conservative component ratings during the design process- in this case, a 35-50 volt electrolytic would be the way to go.

The other is liberal use of TVS devices, or Transient Voltage Suppressors and MOV's.

Adding a relay to isolate the power amp isn't a good solution. Not only would the relay not fit inside the radio, it would add unneeded expense and complexity. Also, you'll note from the schematic that C604 is decoupling the input power right where it comes into the radio, along with HF bypass capacitors and the reverse power protection diodes - which is right where C604 belongs..

As others have said, the reliability of the 706 has been good, so it does lead one to believe that the failures were caused by one or more of the above events. However, the high reliability is in part influenced by the fact that the steady state overvoltage events do not occur frequently, and in some cases could be classified as abuse - like disconnecting the battery while the engine is running.

What Icom might consider doing is using higher voltage electrolytics and some TVS devices, and maybe adding some additional warnings in the operating manual but that's about it. Some might say the warnings would be in a similar class as the ones McDonald's added to their coffee cups: Danger, Hot Beverage, can burn you if you pour it on your lap....

73, Chris

RE: Icom 706 -- Major Defect Found!

by WA6CDE on November 4, 2005 Mail this to a friend!

Well... So far we have had over a dozen hams reply with... IF YOU GET ICOM TO FIX YOURSï¿½ LET US KNOWï¿½ SO THEY CAN FIX MINE� TOO... THEY STAND FAST ON THE ... NOT OUR PROBLEM WHEN A PART FAILS... AND NEVER HEARD OF IT!!!.. and use the old ... your just a stupid hamï¿½.a dummy insinuations.. So its your fault our radio or its parts have failed....

These are just some of the emails I have gotten back from ï¿½CUSTOMERS of ICOMï¿½

Yes the spikes from the starter and headlights are quite large but, the worst offender seems to be the heater blower motor ï¿½ talk about a transmitterï¿½ ouchï¿½

While true that the caps blowing up may be a fluke (Not ICOMS problem but rather the parts vendor) It appears not to be uncommon and damaging (Even ICOM finally admitted that they had 706 listed in their database as having the same problems for repair)

I agree and the point of the article was the voltage ratings which is very close to what the design is However, as one pointed outï¿½ it is NOT only the voltage of design but also, the UNIT HEAT that contributes to the failure of the parts.. I too have noticed that the unit gets very hot mounted away in the trunk. well above what I would call normal (you canï¿½t hold your hand on the back of it after a QSO) and wonder if this also contributes to the failure mode of the capsï¿½

As another said.. do the fan modï¿½ and it will save the unit.. I plan to on mineï¿½ thanks..

As to the Ctk breakerï¿½ yes it is NOT THEIR for its current protection but rather as a high current switch.

As to the leaving the finals on or spiking them when the power goes off and on wellï¿½ every time you start the car your doing just that but, in reverse tooï¿½ as these caps will contribute as well as absorb currentï¿½ so when you start the car.. and the battery goes down due to the loading ï¿½ guess what happens to the ICOM ï¿½ ever put a volt meter across the battery when you put that dead short of a starter on itï¿½ ???

No I think the aviation group might have it right... Keep the radios off line till after you start the carï¿½ a inrush surge is much better than a out rush and then a inrush ï¿½ but, the IR drop of the ckt bkr as well as the wiring will keep it down to a slow run from what we have found ï¿½ however, Alan K0BG�s concerns of the unit providing ground if the engine thus fusing the negative leads also to keep the current from flowing back through the radio mountï¿½ would then be isolated if one had the dual master radio switch such as we suggest instead I would rather be concerned about ground loops starting to develop if one goes grounding things in different placesï¿½

If the finals develop a slow current leak (under 30 amps) you could end up with the battery being un-useable to start the car if allowed to set for several hoursï¿½ all while the fuses wonï¿½t blow isolating the bad radio from the car battery.

How many time will the battery cycle before going badï¿½ unknownï¿½ but, one can be assured that its life will be shortened due to itï¿½

Here are some pictures of the bad cap.. for you to see... (I have sent them to the webmaster to add to the article .. please see above)

Rememberï¿½ It may not be a problem right now for your radioï¿½ but I am sure ï¿½ it willï¿½.

Thanks for all the input on the subject.

Icom 706 -- Major Defect Found!

by KI4LYX on November 4, 2005 Mail this to a friend!

I spent 10 years designing automobile electronics. Many of the comments that have been posted are correct but need to be explained. The starter inductance is the cause of voltages exceeding the battery voltage. The battery internal resistance determines if the termial voltage can spike during starting. A 16 volt spec capacitor directly across the battery terminals is marginal, 35v spec would be fine.

I expect this one case would be traced to a particular battery/starter/wiring issue. This is why many people have not seen the problem. The possible wiring issue is a function of the terminal resistance from the starter to the battery and how the radio contacts are made at the battery. If they are a lower impedance to the starter than the battery the voltage could spike up.

RE: Icom 706 -- Major Defect Found!

by N0TONE on November 4, 2005 Mail this to a friend!

Have previously been a diagnostician in automotive electronics. I agree with the postings that indicate this is not an Icom problem.

If, at the battery, you can exceed 16V, then you have a problem in the vehicle. When was the last time you cleaned the connections to the battery? Resistance developing at the battery connections can easily cause loss of regulation.

AM

RE: Icom 706 -- Major Defect Found!

by WB2WIK on November 4, 2005 Mail this to a friend!

I checked every 12Vdc-powered rig (schematically, anyway) I have, and they all have something like this: 16v electrolytic capacitor(s) across an unswitched power line. So, it's evident this isn't exactly uncommon.

I've used most of my rigs mobile (except the ones that can't be 12Vdc powered or are really large and heavy) and I've never had a failure in any of these capacitors, yet. My Yaesu VHF-FM mobile rig has similar caps across the line and it's been hanging under the dashboard for years, including with the doors locked, windows up on sunny, hot summer days when the car interior temperature reaches >150 degrees F, and I've started the car thousands of times under those conditions and it still hasn't failed.

I suspect any failures are component-related, not due to shabby design. Shouldn't cause a fire, since the components, circuit boards, wiring and connectors are all UL flame rated as "non flammable" or self-extinguishing materials. They can burn, smoke and smoulder but shouldn't sustain an actual fire.

This sounds like a solution looking for a problem...

WB2WIK/6

Icom 706 -- Major Defect Found!

by W5EEX on November 4, 2005 Mail this to a friend!

I have a Yaesu 897 and I took a look at the specs. It is rated for 13.8V +/- 15% which would make the maximum input voltage 15.87V. They also offer a warning about transients due to automotive installations. I would think Icom has a pretty similar spec and warning. 15.87V max
would still be inside the limits for 16V caps, although I would not want to sustain operation at that input. When the specs say 15.87V (or whatever Icom's spec is), is DOES NOT mean it is ok to exceed it for ANY length of time by 2X or 3X the max.....that's why there is a spec
for max input. So I would not call this a defect in Icom's design as long as the specs are maintained.
73

RE: Icom 706 -- Major Defect Found!

by WM5Z on November 4, 2005 Mail this to a friend!

<<"So when you go to start the car you could be placing at least 2 to 3 time (30-45 volts) of the battery voltage across them.."

How so? Your battery can only provide 12 volts and that drops to 10 or 11 while cranking the engine. Where do the rest of the volts come from?

73,

Mark K8MHZ">>

Even tho the battery itself only supplies 12 v, the starter motor is an interrupted, magnetically charged inductor. It can induce several times the supplied voltage.

Here is a little experiment you can do. Connect a small transformer primary across a AA cell. Now with your fingers across the transformer, disconnect the battery. Made you jump, didn't it? Even an old fashioned ohm meter bias can induce quite a jolt.

A car battery really doesn't have that much transient suppression. It really only presents about 100 uF of capacitance per cell, but there are 6 cells in series, so the total capacitance is only 17 uF.

With 100's of amps of current going through the starter you would really need FARADs of C to do any appreciative supression.

Here is what I recommend. Add a couple of ferite cores to the power line. Also install an 18V 5 watt zener across the power lead inside of the radio if one is not already there. (Yeasu radios come with this as their design). The 2 volt added peak will not hurt a 16 volt cap for this short a time period.

Looking at the pictures in the original article, though, I am more inclined to believe the damage actually might have come from excessive summer time temperatures with the radio mounted in a closed car. If the original caps were rated at 70 deg C, and the car was parked in the sun, I would guess that this temperature could easily be reached. Leave a window slightly opened in the summer. You would not believe the temperature difference this little bit of ventalation can afford. Here in the New Mexico desert I have seen the temps inside a closed car reach 190 F. It will burn your hand if you touch things inside.

Steve/WM5Z

RE: Icom 706 -- Major Defect Found!

by WA6CDE on November 4, 2005 Mail this to a friend!

EOZ...
yes the radio still works fine... we replaced the cap
a whopping 96 cents.
with another which was rated at 35 volts... instead of the 16 as listed in the shop manual... ( Alan K0BG said he shop manual showed the part as being a higher voltage than the 16 volt one we removed... yes it is original) So at one time we think they did have a higher voltage set of caps in them

No...
If not for the white smoke which came out of the radio... I would not have known the cap had blown... It did not blow the fuse or show any signs of damage other than the liquid on the metal cover which started to corrode. We were told that some had this liquid eat the ckt board on theirs. thus it might be a good idea to check... by removing the cover...

Look for the top to be deformed like shown in the picture.

Yes

We checked the radio with the bad cap in it and it still worked

So how is one to know?

thanks for all the info and help

RE: Icom 706 -- Major Defect Found!

by KD6NEM on November 4, 2005 Mail this to a friend!

Now that this article has reappeared on the front page of eHam after a number of months, I'd like to mention that there is a well documented problem with defective capacitors found in the PC industry. There was a period of time where a number of capacitor manufacturers (primarily Chinese so far as I know) used a defective formula for their electrolyte. Depending on useage it took anywhere from almost two to three or four years for this to show up. The results are bulging or leaking caps. I have never seen this on any smaller than 470uf, though normally only 1000uf and larger, at least for personal computers. I have replaced capacitors in somewhere between 50 and 75 motherboards, and have seen a number of switching power supplied go south because of this because of blown caps as well. Many motherboard makers ate a lot of these on warranty. Probably was a primary contributor of a few going out of business. There were millions of these bad caps used in consumer electronics in the past four or five years.

By the way, I have yet to see a motherboard be fatally damaged by the electrolyte leak, though I suppose it could happen. I have had to scrub with a Q-tip and rubbing alcohol a few times, and confess that surface mount components are not easy to clean around.

But the thing I don't get is that these are Japanese Caps, and so few radios have apparently been affected. Very likely just a few isolated, completely unrelated incidents?

Still, a quick inspection to see if they are bulging couldn't hurt. And yes, installing JAPANESE caps rated for 35 volts would be what I'd do if I saw any bulging ones.

73,

Stu KD6NEM

RE: Icom 706 -- Major Defect Found!

by N6AJR on November 4, 2005 Mail this to a friend!

If you go to a auto parts store, you can buy for about 10 bucks, a constant duty solinoid. this is likem a ford starter relay, but made to stay on. you hook a fat wire to the battery and a fat wire to the radio, the relay is bolted to ground and an small switch to the control lead ( 12 v from the fuse panel??) on the relay turns it on and off. these will handle several hubdred amps. easy fix for any car needing a high currrent switch. I used it in my pickup/camper to connect the camper battery while running to charge it and then shut it off while parked so using the camper battery did not kill the starting battery

by the way, don't use a ford starter solinoid, they are going to catch fire in about 27 minutes of constant use, (don't ask how I know) use a constant duty solinoid, its made for this.

Icom 706 -- Major Defect Found!

by KC0MQR on November 4, 2005 Mail this to a friend!

Ok several have said a battery is the best protection from the spike and everything should be fine. Simple test will prove this!!! Place a good volt meter on the battery and crank the engine. You will notice the voltage drop to about 10v and then gradually build back up to 15 or 16v. Wheres the voltage spike????

RE: Icom 706 -- Major Defect Found!

by W8JI on November 4, 2005 Mail this to a friend!

Wow, what a bunch of varying opinions!!

I'm sure it's not a chronic failure or a bad design, however.... placing a marginal voltage electrolytic cap across a line that cannot be current limited or protected in equipment where the line is subjected to transients will probably ruin a few radios. Whether that is acceptable or not is up to the manufacturer.

The people who don't have radios ruined will say "oh well", but the poor guy who totally loses a $1000 radio because of something that for a few cents could have been prevented probably won't be very happy.

It certainly isn't a major design flaw or a major problem, it's just one that will really *^^% a few customers off royally.

The vast majority will never have a problem, but the poor fellow who loses $1000 will not be very happy. It's like the guy who buys a car and has the engine kick a rod and catch fire 1000 miles after warranty is out. I'm sure that is what we have going on here.

73 Tom

RE: Icom 706 -- Major Defect Found!

by THERAGE on November 4, 2005 Mail this to a friend!

Oh geez. ten years in production and someone decides that maybe there is (oh i'm sorry-"A MAJOR DEFECT FOUND!!") a problem with the 706's because theirs blew up. Don't you think that if there was an issue with the 706's, Icom would have a recall and fixed it at NO charge? Before you go running to the store with a dead radio and big crocodile tears, be careful what mods you do inside/outside of the radio. Make sure that you wired the rig per the manufacture AND there are no issues with your cars electrical system.

RE: Icom 706 -- Major Defect Found!

by AA4PB on November 4, 2005 Mail this to a friend!

Wheres the voltage spike????
-------------------------------------------
I agree that a good battery will filter much of the spikes however, using a voltmeter is not a valid test. The spikes are very narrow pulses and you need a storage scope to see them.

Icom 706 -- Major Defect Found!

by N0AH on November 4, 2005 Mail this to a friend!

Sounds like a Yaesu rig- Out of the box, they sale you 80% of the radio then expect you to buy the remaing 20% over time in accessory items and replacement parts to make the stock radio acceptable. (Yes, that was a sentence run-on)

Icom 706 -- Major Defect Found!

by K4IQT on November 4, 2005 Mail this to a friend!

Many years back I was involved in the design of low-voltage high-current systems, then moved into the design of electronic systems directly interfacing with inductive relay coils. We worked in 24v and 50v systems, and in both cases always used at least 100v capacitors. Weak spots in circuitry for NASA and for telco's is just not tolerated.

Apparently Icom has never heard of derating. The few cents additional cost to use 35V capacitors should not be an issue on the comparatively short production runs that most ham gear has. This is more likely just an engineering oversight, and since it is not causing a high percentage of warranty failures it is not considered a maintenance issue by Icom.

They are not the only ones missing the boat on derating - my Ten-Tec Argosy and the Yaesu FT-301D I wisely sold years back have some 16v electrolytics, too. Fortunately I gave up HF mobile back in the days of the Heath monobanders.

RE: Icom 706 -- Major Defect Found!

by W8JI on November 4, 2005 Mail this to a friend!

by KC0MQR on November 4, 2005 Simple test will prove this!!! Place a good volt meter on the battery and crank the engine. You will notice the voltage drop to about 10v and then gradually build back up to 15 or 16v. Wheres the voltage spike????>>

Bad measurement technique. You need something that will detect and display transients. A volt meter won't do it.

Icom 706 -- Major Defect Found!

by N0AH on November 4, 2005 Mail this to a friend!

Icom 706
Cheap Components
Must be MFJ

RE: Icom 706 -- Major Defect Found!

by W4CNG on November 4, 2005 Mail this to a friend!

Glad I don't own any ICOM rigs. Whew, just missed this one with my Yaesu rigs, which have other issues, but do not blow up on Starter Transients cause they are off line until after the engine cranks, transients detected with O'scopes not Voltmeters.
Steve W4CNG with 5 second delay to On-Mode master start Relay power contactor.

Icom 706 -- Major Defect Found!

by W5EEX on November 4, 2005 Mail this to a friend!

Gimme a break here.....where did some of these guys get technical training? Since when can you measure transient voltage spikes with a voltmeter? Believe it...there are plenty of spikes running around with the starter is cranking, when compressors kick on and off, etc....that's why the radio manufacturers put warnings in their user manuals about it.....if you think that voltage at the battery is clean DC, get a high frequency scope and do some snooping around.....then you will want to be careful plugging your $1000 radio onto that power bus.
73

RE: Icom 706 -- Major Defect Found?

by K4RAF on November 4, 2005 Mail this to a friend!

My fuse failed, can I write a "Buss 20A - Major Failure Found" if I make clear by TWO (2) Hi Res Glossy photos that it opened as designed?

Bad batch of electrolyte, cap vents opened as designed...

This is nothing more than hype with a couple million in the field. How do I make my 2 - 706MKIIG's fans stop running in receive, short of running external blower? They're in the open air on the bench! Heat is far more of a concern by my experiences. 706's run !HOT! ???

Punch Out - Go Home !!!

Icom 706 -- Major Defect Found!

by KILOWATT on November 4, 2005 Mail this to a friend!

Occasionally, we all buy ourselves a lemon. Yaesu, Kenwood, Ten Tec, Icom.....Ford, Chevy, Toyota, Volkswagen.....It's inevitable. Everyday on the assembly line isn't perfection.

And please keep in mind; Icom doesn't manufacture the individual components of their radios. If you got a bad capacitor or two then it's more likely that Icom's specs were correct but the manufacturer of the caps failed on their quality control. Hey, it happens!

RE: Icom 706 -- Major Defect Found!

by KILOWATT on November 4, 2005 Mail this to a friend!

>Glad I don't own any ICOM rigs. Whew, just missed this one with my Yaesu rigs, which have other issues, but do not blow up on Starter Transients cause they are off line until after the engine cranks, transients detected with O'scopes not Voltmeters.
Steve W4CNG with 5 second delay to On-Mode master start Relay power contactor.<

I own Ten Tec rigs and have discovered a major flaw with them. Must rebuild the PTO's every few years. Why do I keep buying them? They build the best damned CW rigs on the market. Guess I'll have to learn to live with the PTO rebuilds, huh?

The Icom 706 gives you some pretty big bang for the buck. Despite the occasional defective part, they're a great radio, from what I've seen and read.

As I've previously stated; Everyone builds the occasional lemon.

RE: Icom 706 -- Major Defect Found!

by KL7IPV on November 4, 2005 Mail this to a friend!

I bought the original 706 in 1996 and it played well until I sold it in 2000. I then bought the MkII then have used it with out a problem until I tried 60 meters. I got it fixed and it is permanently mounted in my diesel truck. I also have a MkIIG and it plays well all the time. I have the 703 also and have no trouble with it. I figure after all those Icoms, I would have had a failure as described by now. Since I haven't I won't say it CAN'T happen but I am not going to spend any time worrying. It just isn't worth the time. I will just play and enjoy until such time the little bugger fails.
73,
Frank
KL7IPV

RE: Icom 706 -- Major Defect Found!

by N5EAT on November 4, 2005 Mail this to a friend!

I've had an original 706 since 1995. It probably did 75,000 miles in one car before I retired it to in house duty. I install my mobiles with parts I purchase at truck stops. I've done everything I could possibly do to this radio to kill it. It won't die. (however, i've had 2 IC-703's and both died quick deaths running off a nice power supply into resonant antennas). There are ways you could wire a radio into a car and possibly expose the rig to some high voltage spikes if certain ignition equipment were malfunctioning. It's never happened to me with any of my gear. And this is one radio that ICOM has manufactured of late which doesn't have many reliability problems. This problem is serious, but I think extremely rare.

RE: Icom 706 -- Major Defect Found!

by NN8Y on November 5, 2005 Mail this to a friend!

There are lots of inductive electrical loads in a car that will produce transients on switching, sometimes huge ones.

A major manufacturer's spec is something above 200 V, positive or negative, meaning any device on that car has to be able to withstand 200+ V spikes.

The same manufacturer had a bad habit, for many years, of using electric radiator cooling fans which created spikes in excess of 500 V. This was blowing voltage regulators and climate control modules.

This was solved by installing back-to-back zeners across the fan supply leads.

A fuse will not protect against transients, if they were designed that way they would blow on inrush current every time you turned something on.

I'd put back to back zeners on the power lead, that will protect against spikes of either polarity.

NN8Y
Rob

Icom 706 -- Major Defect Found!

by W9GB on November 5, 2005 Mail this to a friend!

Althoguh proper design is one question - you also have t be careful to examine the capacitor as a potential source for this problem.

Electrolytic capacitor problems are NOT limited to Icom - in fact a IEEE Spectrum article pointed out maor problems in proper manufacturing (Far East) -- that hit most computer motherboard mfg (failed motherboards, exploding caps).
http://www.motherboardrepair.com/

Look at this web site of images - if you doubt!
BTW, I repaired by nephew's HP Pavillion after replacing 12 of these "base caps" (one hour of bench work on a 4-layer motherbord) - from dead to back to life!
http://www.motherboardrepair.com/index.php?sec=images

BTW, both MicroCenter and an HP Servcie Center missed this proper diagnosis. When I took the motherbaord out fo the case (whcih they likely did not do) - the daignosis was straight forward with both nose and eyes!!

w9gb

RE: Icom 706 -- Major Defect Found!

by GM6TVR on November 5, 2005 Mail this to a friend!

My 706 has experienced mega untroubled stops and starts when installed in my car. This is just a thought - Some people may have connected their rig directly to an HGV 24 volt supply, or even suffered a direct lightning strike, any of these events can cause a major defect!!!!!!!!!!!!!!!!!
HGV or lightning bolts, try to keep it at 12 volts!!!!!

John www.johnblack.org

Icom 706 -- Major Defect Found!

by KG6LFN on November 5, 2005 Mail this to a friend!

I am sorry to hear about your problem.

I use two high quality (aircraft) internally suppressed power relays in series on the high side. One relay is wired normally open and is closed by the ignition switch, while the other relay is wired normally closed and will open when the starter is engaged. I use the normally closed relay as a failsafe to open the power circuit to the radio thereby preventing the voltage spikes from damaging my radio just in case the starter is engaged with the radio accidently left on.

I fuse only the hot lead as I have seen the damage caused by open low side fuses when electrical equipment sought the path of least resistance and found a ground elsewhere: smoke check failed! Unless the radio (including the antenna coax shield) is fully isolated from the rest of the common ground which is completely impractical, I don't advise low side circuit protection unless you are obliged to hook your battery leads backwards on occasion . To the brainy types who can't wait to tell me how wrong I am about this subject: save it, wire your radio the way you want to and I'll do the same.

I don't suggest this is the best or only way to wire a radio but it has worked flawlessly for me - even on my newer Icom that sparks when you connect the power lead!

RE: Icom 706 -- Major Defect Found!

by AD5X on November 5, 2005 Mail this to a friend!

I use in-line home-brew transient suppressors on my IC706G and IC-703, just to be safe. The suppressors are cheap and easy to make. Details at www.ad5x.com.

Phil - AD5X

RE: Icom 706 -- Major Defect Found!

by AA4PB on November 5, 2005 Mail this to a friend!

If you power a relay from the vehicle accessory line then the relay will open just before the starter engages and close again as soon as the ignition switch is returned to the run position. There is no need to use two relays.

The purpose of a fuse in the negative lead is to *prevent* problems with the radio and wiring in the event that starter currents attempt to flow thru the radio grounding system when starter grounds fail. A fuse should always be used in the negative lead any time that the radio's negative lead is returned directly to the battery terminal.

RE: Icom 706 -- Major Defect Found!

by WB4DX on November 5, 2005 Mail this to a friend!

I have had all 3 versions of the 706, yes, their receivers leave a lot to be desired (UHF /VHF) Almost as bad as an HT! I couldn't use any antenna other than a 1/4 wave 2 meter antenna due to intermod.
I won't have another one in my car. Workhorse......Not!

Icom 706 -- Major Defect Found!

by NJ3F on November 6, 2005 Mail this to a friend!

This is simple stuf.

1. a 16v cap is 16wvdc working voltage. not peak.

2. if you replace it with a 35wvdc cap, the cap wont
work as well, and will degrade over time and become
leaky (current not liquid).

3. it doesnt cost much more, to use higher votage
caps, why do you think they design equipment this
way? because thats the proper component for the job.

look at other factors, maybe a few bad components got
through, maybe the heat in the car had something to
do with it. if you change to 35v caps you are taking
a big chance, they wont filter as well and over time
will get worse.

Icom 706 -- Major Defect Found!

by YD0NHR on November 6, 2005 Mail this to a friend!

Maybe that major defect happened too in my ICOM V8000 2m rig.Two times its burns the PA when installed at mobile. So I decide to use as base rig and never give anymore trouble.

Icom 706 -- Major Defect Found!

by K4SFC on November 6, 2005 Mail this to a friend!

Reference the original comments. All I can say is I've had all three of the Icom 706 series. That covers roughly ten years, and NEVER had a problem. I forget about half the time and crank my car with the radio still on. AND that also covers six different cars between the wife's and mine.
Reference the comment by NE0P! The receiver in each of the three IC-706 series got better and better. MY IC-706MKIIG has a better/more sensitive receiver than my Icom 746PRO does. I DID purchase all of mine NEW!

Icom 706 -- Major Defect Found!

by KE1MB on November 6, 2005 Mail this to a friend!

I have a very beat up, 5 year old 706mk2G. It has been portable with a mag mount on many cars and has run off of many different power supplys. No issues. But I can understand that using a 16volt cap is a bit risky. It is possable that due to the rare nature of the failure that the design stood. I would wonder why one would not consider upgrading any cap that is close to it's rating and not worry about complex high current switches.

RE: Icom 706 -- Major Defect Found!

by W5DXP on November 6, 2005 Mail this to a friend!

What poorly designed vehicle caused this "major defect"?
--
73, Cecil, W5DXP

RE: Icom 706 -- Major Defect Found!

by AA4PB on November 6, 2005 Mail this to a friend!

Starter spikes have been seen as high as 60V on 12V automotive systems. Are you going to replace all the capacitors with 100V ratings? How about the IC's and transistors?

The spikes are very narrow (high frequency components) and they are usually minimized by the parallel capacitance and the series resistance and inductance in the wiring, fuses, etc. Its rather difficult to account for all variables however because the size of the spike depends on the condition of the vehicle battery, the wiring, etc so it can vary even with vehicles of the same make and model.

A good way to protect the radio is with a surge protection diode. Even then if there is not enough series inductance or the spike contains too much energy (long time period and/or high voltage) then the diode will short.

Icom 706 -- Major Defect Found!

by WA2JJH on November 6, 2005 Mail this to a friend!

1)TNX FER the very detailed artical.

Yup them DC-Daylight swiss army knife rigs do have their problems.

Funny, I saw a few people describe and sell the 706 IIG rigs as a commercial rig?!

Guess Icom thinks your getting so much for the money, that Q.C. is frivilous!

I purchased the FT-100D on a close out sale. All or most of the bugs are rare in rigs that are being discontinued.....I hope! NIB with DSP,500hz CW filter and TCXO closed out at $730 shipped. So I think I got a good deal.
I did find out that the only problem not solved was the sensitive 25W PA brick. So I run the rig at 12W out.

Except for the telco style mic jack, it is an OK
rig. The SSB audio is too wide for my taste. I hope to find an INRAD 2.3khz filter to replace Yaesu's 2.7KHZ
filter.

I found it pays not to buy a rig until N4PY or whoever makes PC control software.
The IF shift control on the radio is too small to adjust properly.
Many other hidden functions and controls work better when adjusted by a PC and 3erd party software

Just like the 706, the FT-100D was not a decent rig until Icom and Yeasu listened to Hams complaints.

Too bad that by the time the rig is being discontinued, the manufactuer fixes all or most of the
problems!!!!

Perhaps it is prudent NOT to run out and buy a radio that is just introduced. If you wait a few years after the intro, just about every bug and mod. is published.

I feel it is the same way with computer software.
If you buy XP these days service pack 1,2 and many other patches are on the disk you buy 3 years after the intro of XP.

Again thanks for the very detailed artical
73 DE MIKE WA2JJH

Also by the time a rig is being closed out, you know what your getting for your money. Many hams before you have published fixes and mods.

RE: Icom 706 -- Major Defect Found!

by KG6LFN on November 6, 2005 Mail this to a friend!

by AA4PB on November 5, 2005

The purpose of a fuse in the negative lead is to *prevent* problems with the radio and wiring in the event that starter currents attempt to flow thru the radio grounding system when starter grounds fail.

*****************************************************

Most radios installed in new model cars are mounted to an insulator as it is becoming increasingly difficult to find any metal to attach the radio to around the newer dash panels. If the installer doesn’t include a proper bonding strap between the car and radio chassis, the only other path to ground will be through the antenna feedline shield should the negative side fuse open. And believe me; they open just due to vibration in the hostile environment we call the engine compartment.

I suggest this test to make you a believer: Go out to your car and open your negative side fuse. Turn on your radio – the ground will be afforded by your coax shield if you are using a proper antenna. Go to high power and do a little ragchewing.

Then you can tell me how many problems your low side fuse *prevented*!

By the way, I have never lost a “starter ground” on any of my machinery, nor have I ever had an engine, transmission or rear end fall out. If that is a concern in your machine, see a competent mechanic fast and have him tighten up all of your battery cables!

If you dispute the simple test I offer you, you would probably dispute Euclidean Geometry because you think Euclid was a liar.

RE: Icom 706 -- Major Defect Found!

by KC8VWM on November 6, 2005 Mail this to a friend!

So how is the IC 706 design particularly any different than 95% of the other radios on the market today that are just as equally susceptible to the same problems of voltage spikes in a mobile operating enviroment?

Icom 706 -- Major Defect Found!

by W5PPF on November 6, 2005 Mail this to a friend!

I have had three 706Mk2G's. Used them mobile & fixed for the past 4-5 years, never a problem with any of them. Have my Mk2G in the car now, connected with #8 dc power line direct to the battery with a fuse in the positive side---No Problems after lots and lots of use. And by the way, the receiver is fine!!