TS-940S Power Supply Replacement Kit Ready!

Discussion in 'Radio Circuits, Repair & Performance' started by AK6OK, Jan 12, 2018.

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  1. AK6OK

    AK6OK Premium Subscriber QRZ Page

    Good morning! I have been working with a team of hams to develop a full power supply replacement solution for the Kenwood TS-940S. To install this new system, you remove the entire original power supply, and remove 5 headers from the existing AVR board. Our new board then mounts in the radio using Snap Track as shown. You then simply plug the 5 cables back into the new interface board and mount a New switching 24V power supply. You can see more details at k6iok.com.

    We will be releasing a TS-930S power supply replacement kit in February as well! stay tuned!
    Jeff AK6OK - Rocklin, California

  2. K7JOE

    K7JOE Ham Member QRZ Page

  3. K3RU

    K3RU Ham Member QRZ Page

    Very impressive. Your 940 power supply packages are a real game-changer.

    I have two 940's and one 930, all three a source of "power supply worry". One 940's power supply is completely 1988 original, the other 940 dates to 1986~ whose power supply I refurbished almost ten years ago. I don't have the ambition to rebuild the 1988 940, lots of tedious work.

    The 930's power supply board caught on fire, damaging the PCB severely which I cobbled back-together with "Houdini-like" soldering of burned-out PCB traces and surprisingly got the 930 working again. Don't ask how the board caught fire. "Somebody" (me) accidentally dropped a test lead into the operating radio and shorted the 28V line. I barely got the fire put out.

    I'll be a customer.
    Last edited: Jan 17, 2018
  4. G3YRO

    G3YRO Ham Member QRZ Page

    Yes, I did a lot of research and spoke to a lot of former owners when choosing a new rig 18 months ago . . . and many said they prefer the TS930S over the '940 and '950. I've certainly been happy with mine . . . although I have done quite a few repairs and modifications.

    I'm sure some people will be interested in this kit (although I suspect it would cost almost as much as I paid for the rig!)

    I personally have no desire to change the PSU in my TS930S . . . as the design in the earlier versions is pretty sound.

    I think the only issue is the fact that Kenwood disconnect the PSU output from the rig when you switch off, which somebody discovered can cause a "spike" that blows the Driver Transistors and even the Regulator Trasistors.

    I have got round this by fitting 24V Fans on the PSU and PA Heatsinks connected directly to the main PSU Output. This not only provides a constant load . . . it also stops them getting hot in the first place.

    (it also gets rid of half the circuitry on the PSU board)

    Roger G3YRO
    Last edited: Jan 17, 2018
    K3RU likes this.
  5. US7IGN

    US7IGN Ham Member QRZ Page

    G4COE likes this.
  6. K3RU

    K3RU Ham Member QRZ Page

    If I did proceed with such a wholesale power supply change-out I would very CAREFULLY remove and save the original components and wiring "just in case" I wanted to go back to original. No doubt it's a big step and I would like to know the replacement components country of origin.

    I watched the AK6OK videos ( at K6IOK.com) and am struck how simple the install is....though I was a little queasy watching how the original 940 components were "ripped- out" !

    The "complete tested and ready to install" package is currently $299 USD, not bad IMO considering the potential power supply problems which should be eliminated, hopefully without creating a new set of problems for later.
    Last edited: Jan 18, 2018
  7. K3RU

    K3RU Ham Member QRZ Page

    I think the question of RF Noise was mentioned in one of the videos at K6IOK.com, I'm going to watch them again to be sure.

    Am also going to if possible research the components country of origin.
  8. G3YRO

    G3YRO Ham Member QRZ Page

    Well by the time that was shipped to England and Duty paid, that would be as much as I paid for the whole rig!

    Personally, I would never buy a switch-mode power supply.

    I also feel the simple mods I have done should prevent a PSU issue in the future.

    Roger G3YRO
  9. KA9JLM

    KA9JLM Ham Member QRZ Page

    China. I have used these switchers, They do work.
  10. US7IGN

    US7IGN Ham Member QRZ Page

    Surely it does. But how? Does anybody check them for spurs and other RF noise? IMO problem is not it is chinese but it have not proper RF filtering and it is useless in radios.

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