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Author Topic: Tired of your FT-897 power cutting out when the power cord gets wiggled?  (Read 3583 times)
N0ZYC
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Posts: 20




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« on: March 17, 2013, 10:01:25 PM »

I sure was.  After crawling the web for awhile I found LOTS of people with this problem, but no one seemed to have any specific details on what was causing the problem, and not a lot in the way of fixes.  I even wrote to yaesu to see they wanted a shot at providing a first-time-yaesu owner some quality technical support.  But they only disappointed me.  Despite providing multiple links to discussion threads on the problem, I received the boilerplate "We are not aware of (admitting to) any design problems with the power connector.  We have seen a few isolated (very numerous) reports of this problem, but there is no suggested solution (we are not issuing a recall) for the problem at this time."  So, we're on our own.  Good thing "on our own" is something this group does well, huh? Wink

I finally had my limit last night, every time I move a power cable behind my radio stack, my 897 clicks on and off battery power continuously. (last time it discharged a battery because it didn't cut back in when I was done working)  So the radio went on the bench this afternoon.  I was hoping to find a loose connection, perhaps a bad solder joint on the molex on the inside.  I didn't realize there would be a harness cable to the power board, so that also landed high on my list of things to check.  Many times I've had to repair cold solder joints on board connectors like that which wiggled out of their solder after extended mobile use.

But that wasn't the problem.  Nor was the solder on the jack bad.  Nor the fuses.  The problem it seemed was in the connector itself.  Takitapart.  I had to improvise as I didn't have the proper molex pin removal tools.  I ended up using a pipe cutter to obtain a 1.5" long section of some brass tubing I found in the bin.  The tubing is thin walled and is 4mm or 5/32" OD.  I got mine at Menards, but any larger hardware store and even some hobby shops carry it.  This fit around the female pins on the power cable's molex pins perfectly.  Almost too well.  I actually pulled a wire out of its pin trying to pull it out.  (those are going to get soldered before I finish with this)

The two lock clips disengaged from the molex body when the tubing was inserted all the way onto the pin, but the friction between the tube and the pin was too high to pull out.  So I used a 3/32" allen key (which fit *perfectly*) to push the pin out the back of the molex.  All four pins were easily removed without damage this way.  Be careful to note the polarity before removing the pins!  The hot pins go in the middle two holes, ground in one set of side holes, note which side.  All four got solder wicked into the wire crimp on the pins.

I had examined the male pins earlier and they were clean.  I now had a closer look at the female pins and those were also free of corrosion.  This connector hasn't seen 50 operations, the male pins can't possibly be splayed out…  what's going on here, this should work?  So I pushed a single male pin into the back connector on the radio and immediately realized the problem.  They wiggled.  A lot.  There was NO grip on the pin whatsoever, and room to play.  If I hadn't been holding the pin on via the wire it would have simply fallen out onto the table.  Problem identified.

OK, I've seen this on heavily used molex before, the male pins have just spread out a bit over time, they just need to be crimped back snug.  When I looked, there was a hair of separation, but not really very much, maybe 1/8mm.  I snugged one up to meet with no gap and tried it for size.  NO DIFFERENCE.  wow.  Either there was a manufacturing problem with this run of connectors, or they somehow managed to get the wrong sizes of male and female together! (is that even possible? do they make those pins in metric sizes?)

ok PLAN B.  I got out a pliers and crushed in the connector so there was a little overlap from edge to edge.  Not a lot, maybe 1/3mm.  But the connector was also deformed to a bit of an oval.  Repeat with the remaining three connectors.  Fit is GOOD.  Pins now must be PUSHED in, and PULLED out from the radio.

Before reinserting the pins, I also pried out their lock tabs a little.  Only 1/8mm or so.  Using the tube to extract lock pins like I did will bend them in a little and make them prone to popping out later unless you bend them out a hair before reinstallation.

All pins back in, double check polarity, looks good.  Plug it in.  I immediately notice I have to align it up dead on to plug in, there's no slop.  And I had to be PUSHED in, there's a definite difference.  Power it on.  wiggle.  Wiggle.  WIGGLE WIGGLE WIGGLE!  Nothing.  Had to share. Smiley  Hope you can fix your 897 too.  Hope Yaesu improves their customer support.  I think I'll stick with more Icom and Kenwood in the near future, this hasn't been a very positive first experience.

- 73 / N0ZYC / Nathan
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KE3WD
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Posts: 5689




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« Reply #1 on: March 18, 2013, 02:01:01 PM »

Rather common problem with certain Molex-type connectors, Nathan.  Most aren't really Molex brand. 

When the connection becomes loose, heat buildup at the point due to added reistance can exacerbate the problem. 

Your fix is likely only a fix and not a long term cure. 

Replacement of the plug and socket with new is what we like to do at the bench here. 

The good news is that this is not a design flaw with the plug itself, only with certain runs from certain asian manufacturers and the plugs we order today have gotten better in the way of the metal type and plating used. 

It not only was a problem with Asian manufactured white molex type plugs, even the American manufacturer, Peavey, had notorious problems with such connectors inside their audio power amps at one time. 

You should order up the plug and the socket from the Parts division of Yaesu and replace them, although you may elect to wait until such time as the plug you've tightened should start to fail again.  I'd get 'em in hand and place them on the Spares shelf...


73
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N0ZYC
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Posts: 20




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« Reply #2 on: March 18, 2013, 03:08:11 PM »

It didn't fail due to getting loose over time though.  It always was this way.  The female pins were barely split apart when I took it apart.  I've worked on a bit over a dozen bad molex connectors, and yes, usually crimping them back together is only a temporary fix... I think the spread is caused more by a constant wiggling of the connector, that slowly expands the split until it starts getting intermittent.  Then a bit of arcing makes the problem get rapidly worse as it forms carbon on the contact surfaces.  Normally I take them apart, polish out the carbon from inside the females and around the sides of the males, crimp back down, and reassemble.  Then put some sort of strain relief arrangement on the connector (to keep the wires on the cable from moving side to side as they lead away from the unit) to keep it from happening again.

In this case, the female pin wasn't splayed apart; it looked like new. (and had acted that way since the day I got it, and I got it in "like new" condition)  It really was as though the pins weren't machined properly to fit together snugly.  While my fix may be a temporary fix under some conditions, sitting back in my radio stack and rarely disturbed, I don't expect to ever see it come up again for me.  I agree that replacing the connectors may be the only permanent fix for some users though.  Considering there's a size mismatch, it's probably only necessary to replace one end, though without new ends to test with I don't know whether the cable end (females, too large) or the radio end (males, too small) are causing the problem.  For some it would be easier to replace the connector on the cable.  I prefer "free fixes". Wink

(as for brand, I don't know what their "formal name" is... I refer to anything that looks like that as a "molex type" connector, you'll have to educate me)
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KE3WD
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« Reply #3 on: March 19, 2013, 02:17:11 PM »

I did not necessarily mean that the heat *causes* the problem.  What I remember typing was that the heat from the bad connection serves to *exacerbate* the problem, which means that it will make it even worse over time. 

The problem in your case may well have to do with the *temper* of the base metal that the female part of the connection is made from.  If it can be easily expanded and contracted and does not spring back into its original shape, that's what I'd suspect. 


73
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N0ZYC
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« Reply #4 on: March 19, 2013, 03:08:19 PM »

It wasn't a case of the female not having adequate grip on the male...  there was NO grip.  as in, the pin itself (with no wire attached) falls right off with nothing but gravity helping it.  No tension despite there being practically no distance in the connector's expansion gap.  It looks a lot more like a manufacturing/tolerance issue than a material defect.
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WA9FZB
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« Reply #5 on: March 19, 2013, 05:20:26 PM »

This problem is not unique to the FT-897.  I experienced similar issues with an FT-847, and performed similar "field modifications" to my connectors.  It lasted at least as long as I kept the rig. . .
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KF6QEX
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Posts: 605




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« Reply #6 on: March 20, 2013, 02:52:09 AM »

Molex , like Xerox and  Cleenex is a brand.
http://www.molex.com/
They make all sort of neat stuff  that may or may not be available through the usual suspects like Mouser or Digikey.

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K5LXP
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« Reply #7 on: March 20, 2013, 06:56:32 AM »

Sounds like over time perhaps between best price "equivalent" vendors and liberties with specification tolerances the differences between the mating connector pins has exceeded the operational limit.  As a data point though, the common 6-pin power connectors like these are only rated for a couple dozen mate-unmate cycles at best and per pin are not capable of handling the current (so they use 4 pins instead of 2) .  I know pin fatigue doesn't appear to be the root cause for the current discussion but voltage drop and intermittent connections are a common enough problem whether it's fatigue or poorly spec'd/built connectors.   My standard fix for these is to split some 12 gauge zip cord and run the wires through 2 empty holes of the shell and solder them direct to the board.  At the other end of the short zipcord pigtail I put a powerpole.  While maybe not the ideal power connector the powerpoles are definitely up to the current and mating cycles.


Mark K5LXP
Albuquerque, NM
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N0ZYC
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« Reply #8 on: March 20, 2013, 07:11:02 AM »

it might be practical for anderson to consider fabricating some bulkhead connectors for their powerpoles that are sized to fit into the hole created when you pull out a molex. (of various shapes)  I'd buy a few.
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