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Author Topic: TS-940 "THE FINAL SOLUTION" FOR THE POWER SUPPLY PROBLEMS?  (Read 1146 times)
N6QWP
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Posts: 263




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« on: December 05, 2017, 04:38:12 PM »

I started this topic earlier (this date) in Mods and Repairs, on the bottom of the third page under the "TS-930/TS-940 POWER SUPPLY CROWBAR" heading, but it deserves it's own thread.  Please look back there for a foundation of this thread.

I, like so many others, have been on a "Holy Crusade" to find a solution to the major problem of the great old venerable TS-930/TS-940 transceivers.....the vulnerable power supply.

Researching the many different mods published, and asking countless questions here on the Forums, I became overwhelmed and disheartened because of the many options......and the various drawbacks that each seemed to have (as commented on here in the Forum).

Since I was NOT very knowledgeable or experienced on working on these rigs, I was searching for something that was straightforward, easy to do and did not require an advanced engineering background.

I believe that I HAVE FINALLY FOUND IT and would like to share what I have found with the many others who own these great old radios and are also looking for a SIMPLE, RELIABLE MOD that addresses all of their concerns and is something anyone can do.

I've been lucky enough to have been able to acquire a prototype of AK6OK's newer "TS-940 Power Supply Interface board for field testing.....and want to alert those interested, that a Solution to the problems is going to be available shortly, that is simple to install, requires no special equipment or skills and IT WORKS!!

I will add more to this thread after testing the mod for a while (expecting the updated latest edition within a week)....just wanted to let others know that SOMETHING GREAT IS IN THE WORKS!
« Last Edit: December 05, 2017, 04:55:46 PM by N6QWP » Logged
K8AXW
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Posts: 6380




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« Reply #1 on: December 06, 2017, 10:48:45 AM »

Quick question....what is a power supply "interface board?"
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N6QWP
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Posts: 263




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« Reply #2 on: December 06, 2017, 01:43:49 PM »

Replaces the old AVR board.  Interfacing the "new" supply with the rig's various circuits.  Supplies the required voltages from the supply to the TS-940.
« Last Edit: December 06, 2017, 02:04:31 PM by N6QWP » Logged
K8AXW
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Posts: 6380




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« Reply #3 on: December 06, 2017, 08:43:27 PM »

Thank you. It's terms like this used with old gear that vapor locks this old brain.
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N6QWP
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Posts: 263




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« Reply #4 on: December 07, 2017, 08:42:59 AM »

I understand well.  Sometimes, we just have to mutate along with the changes of "progress".  While, I too, go kicking and fighting it, I try to make it as simple as possible (taking the path of least resistance).  ;-)
« Last Edit: December 07, 2017, 08:46:17 AM by N6QWP » Logged
WA1RNE
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Posts: 999




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« Reply #5 on: December 07, 2017, 09:25:40 AM »

Quote
I've been lucky enough to have been able to acquire a prototype of AK6OK's newer "TS-940 Power Supply Interface board for field testing.....and want to alert those interested, that a Solution to the problems is going to be available shortly, that is simple to install, requires no special equipment or skills and IT WORKS!!

 I'd be very careful about implementing this modification prior to doing some of your own analysis.

 I took a look at the technical specifications of the smaller Phoenix power supply as well as the mounting arrangement being used by the authors and there are some red flags that pop up:


 1)  Most importantly, the 240 watt full power rating of the supply is specified at 24 volts DC and specifically states, quote:

      "Setting range of the output voltage (USet) 18 V DC ... 29.5 V DC (> 24 V DC, constant capacity restricted)

 That means the output current is DERATED for output settings over 24 volts, but they don't specify what the derating is.  You need a minimum of 28 Volts to run the PA which is 16% of the nominal voltage rating - not accounting any sag from line/load regulation tolerances.

 2) The dynamic load regulation specification is <2% which is critical. Subtract that from the 28 volt no load setting and you end up with 27.44 Vdc, which means you may need to make the no load setting 28.56 Vdc to account for that - which further exacerbates problem #1.

 3) The mounting arrangement is via Velcro pads. In my opinion that's not a finished modification and is loaded with obvious risks.

 The boost spec is not going to be of much help either - that only applied to 12 ms short term load spikes.


...Again, I'd use caution before pushing ahead with this mod.


...WA1RNE



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N6QWP
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Posts: 263




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« Reply #6 on: December 07, 2017, 11:20:43 AM »

I see that you are referring to the 10 amp supply and not the 20 amp supply, but I would again refer back to W3AFC's pages on the TS-930 mod

Hundreds have successfully installed the Phoenix supplies in the 930's.  As yet, I have found NO reports of any kind of power supply problems.....and many of them used the 10 amp supply.

Lately, there are numerous 940's that are using both of those supplies.  With the 20 amp supply, there seems to be more than enough extra power to enable care free operation.  Since most, I believe, would be using the rigs on SSB, the duty cycle is quite limited.....and the 10 amp supply seems to be just barely adequate.

For CW or more power hungry modes, then the 20 amp supply should be adequate.....and for worry free SSB operation, I personally, would rest very easy.

Of course, someone will always find something to be concerned about with something new.....but, given the alternatives (with the history of many "catastrophic" failures), do your due diligence.....and decide for yourself which mod seems to make the most sense.

My present setup, using to 10 amp supply, is only temporary....until I can get the 20 amp supply and the updated board.  Obviously, that is the way to go.
« Last Edit: December 07, 2017, 11:41:22 AM by N6QWP » Logged
N6QWP
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Posts: 263




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« Reply #7 on: December 07, 2017, 11:50:43 AM »

I might also point out, that I too, think that the 10 amp supply is marginal....and since I will be using the rig as a driver for my 500 watt 30L-1, I will only be using about 50 some watts for that purpose-and on SSB.  

I would think that most of those using the 10 amp supply were also operating at somewhat reduced power (if they felt uneasy about it-or experienced any signs of "fm-ing").

For that use, I feel comfortable with a 10 amp supply (until I can replace it with a 20 amp one).  After that, I will not be uneasy using the rig on CW or SSB at it's full output rating.
« Last Edit: December 07, 2017, 12:03:45 PM by N6QWP » Logged
K8BYP
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Posts: 39




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« Reply #8 on: December 14, 2017, 12:39:01 PM »

Quote
I've been lucky enough to have been able to acquire a prototype of AK6OK's newer "TS-940 Power Supply Interface board for field testing.....and want to alert those interested, that a Solution to the problems is going to be available shortly, that is simple to install, requires no special equipment or skills and IT WORKS!!

 I'd be very careful about implementing this modification prior to doing some of your own analysis.

 I took a look at the technical specifications of the smaller Phoenix power supply as well as the mounting arrangement being used by the authors and there are some red flags that pop up:


 1)  Most importantly, the 240 watt full power rating of the supply is specified at 24 volts DC and specifically states, quote:

      "Setting range of the output voltage (USet) 18 V DC ... 29.5 V DC (> 24 V DC, constant capacity restricted)

 That means the output current is DERATED for output settings over 24 volts, but they don't specify what the derating is.  You need a minimum of 28 Volts to run the PA which is 16% of the nominal voltage rating - not accounting any sag from line/load regulation tolerances.

...Again, I'd use caution before pushing ahead with this mod....WA1RNE


THAT IS GOSPEL. Ive fought that dragon too, the MFJ 30A supply I have (great piece of equipment, not knocking it) but it WONT supply 30A at 5V.
I tried to source LV and high current to a heater with it, and it tripped out.

Modern DDC PSes do have advantages of high speed fault tolerance, BUT, yes, be careful. Once all the smoke is out, electrics dont work any more.
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N6QWP
Member

Posts: 263




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« Reply #9 on: December 14, 2017, 08:57:34 PM »

Again, the Updated Mod calls for the 20 amp supply-NOT the marginal 10 amp one.  Should be more than enough leeway to handle the PA of the TS-940....with room to spare.

We're NOT talking about constant high draw heaters here.  If the 10 amp supply barely handles the SSB requirements, then, I would think, the added cushion of an extra 10 amps should alleviate any concerns for this type duty (even allowing for lower output at the higher voltage)?

There are, apparantly, already many of these 20 amp Phoenix supplies now being used in TS-930's and a good number of 940's......and so far, no problems have been reported by W3AFC or others here.
Still seems a far better track record than sticking with the original high heat, prone to failure pass transistor supplies (with the notorious catastrophic over voltage blow outs) of the 80's used in these old Kenwoods.

I'm placing my money on the newer designed "high tech", well proven, industrial grade supplies and the newly designed interface boards that are simple to install.


« Last Edit: December 14, 2017, 09:21:38 PM by N6QWP » Logged
K8AXW
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Posts: 6380




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« Reply #10 on: Yesterday at 10:35:53 AM »

QWP: Has AK6OK published his board online?  How about how the power supply is to be wired into the 940?
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N6QWP
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Posts: 263




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« Reply #11 on: Yesterday at 11:19:43 AM »

AXW-I have not conversed with Jeff this week.  Supposedly, the "new" board modification will be ready sometime over the Holidays.  Videos and info are to be updated on his website then.

Wiring the output of the new Phoenix power supply is a no brainer.  Just install the power supply where the old power transformer used to be and the output plugs directly into his new Interface board.  Most of the associated old wiring, the transformer, heat sink with pass transistors and VR's, fan, capacitor board and AVR board are removed.

The required old connectors that went the old AVR board (only a few of them are now used), plug directly onto the new board and converter.  Pretty straightforward=(everything is marked on the new board)....nothing left to chance or requiring figuring out where anything has to go.  "PLUG AND PLAY".
« Last Edit: Yesterday at 11:29:22 AM by N6QWP » Logged
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