Is the ts930s really that unreliable? New owner

Discussion in '"Boat Anchor" & Classic Equipment' started by KG7HVR, Feb 3, 2020.

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  1. KG7HVR

    KG7HVR Ham Member QRZ Page

    Picked up a super clean 930 at hro. They thought it didnt work so it was pretty cheap. But it did work.
    After a few days of reading im not sure its wise to use it without some modifications.
    I used it for about an hour on 75m Saturday night and compared to my ts2000 every one agreed the 930 was alot stronger and sounded great. Once i started reading and noticed that the rig gets fairly warm i decided to not use till I know more.
    Theres a kenwood tag on the tuner dated 1994. Im not exactly sure what it means. Maybe serviced in 94. I dont see any resistors in the powersupply housing like ive seen in other posts. Mine is also an early serial number 3,070,000 it works very well and i would like to keep it that way. However i have many radios and really dont need any serious problems or projects.
    I think a good start would be to determine how to mod the fan to always on to protect the pass transistors from extra heat. If anyone knows how let me know.
    Ive pretty much read all i can find on the 930 and am now reading about the 940 since they have similar issues.
    Any advice would be appreciated. And i hope i posted this in the appropriate section.
    73
    Kg7hvr 20200202_205220.jpg 20200202_205014.jpg 20200202_122228.jpg 20200201_212649.jpg 20200203_123013.jpg
     
  2. N8YX

    N8YX Ham Member QRZ Page

    Best thing to do:

    Get a Compudigital PSU/regulator conversion kit, replace the stock PSU and use the radio.

    I did this to my '930 about a year and a half ago and the rig has been in almost 24h/day operation since then. Runs cool; works well.
     
  3. KG7HVR

    KG7HVR Ham Member QRZ Page

    Ok, i saw those quint brand ones. What did you go with? And how much and where?
    Did your original supply fail?
    Is it really that common for them to fail?
    I think i read the real issue is when the pass transistors overheat and fail they send 40v into everything and only the finals survive and the drivers and other things get taken out.
     
  4. G3YRO

    G3YRO Ham Member QRZ Page

    There is nothing fundamentally wrong with the original PSU design . . . so don't waste money replacing ANY of it !

    There is just a stupid design error which CAN cause a spike (which can cause regulator transistor failure) . . . that is the fact that Kenwood disconnect the rig from the PSU when you turn it off !

    A simple solution is to remove BOTH the original fans . . . wire 24V computer fans directly to the output of the 28V regulator.

    This provides a permanent load on the PSU, and stops the spike.

    But it also stops the PSU and PA Heatsinks getting hot in the first place.

    I love my TS930 . . . and the big advantage over the '940 and '950 is that all the semiconductors (inc ICs) are still available !

    Roger G3YRO
     
  5. KG7HVR

    KG7HVR Ham Member QRZ Page

    Thanks for the reply Roger and I actually sent you an email the same day I bought the radio because I already knew you had one
     
  6. VE7DQ

    VE7DQ Ham Member QRZ Page

    Roger's suggestion would work fine. If the PS fan is currently noisy, and many of them are, I'd go that way.

    In the past, I've added a resistor from emitter to collector across the transistor that switches the PS fan on and off. Offhand, I don't recall the value, but if I had to guess, it would be about 47 ohms, 1 watt. Adjust value to suit. The resistor is added under the small power supply board beside the transformer. The fan will then operate at a lower speed until the transistor is switched fully on according to the requirements of the temperature sense circuit.

    At one time, there was a service bulletin and kit of parts to address heat issues in the early '930s. You might look for the bulletin. There are several good TS-930 resources on the web.

    The circuit board is a bit snarky to deal with. If you are up to the adventure, I can dig out my service manual and tell you which transistor it is. Do you have a service manual?
     
  7. KG7HVR

    KG7HVR Ham Member QRZ Page

    Now would that keep a load on it? My fans are pretty smooth.
    I do have a service manual but im not sure its the correct one for my 3,070,000 serial number radio.
    I dont know the voltage of the stock fans. Im wondering if you have 2 pc fans in series where is a good place to obtain the 28v to run them and would a dropping resistor be necessary. Or could i use the stock fans and do it that way to keep a load
     
  8. KG7HVR

    KG7HVR Ham Member QRZ Page

    Do you have any pictures of the fan modifications to your ts930?
     
  9. G3YRO

    G3YRO Ham Member QRZ Page

    It's such a simple mod ! You can simply tack the leads onto the thick wires on the top of the PSU board . . . and just disconnect the original fans (no need to modify any of the circuitry on the board that controls the original fans . . . just leave it there, doing nothing)

    As I said before, the main reason for doing it is to provide a constant load on the Power Supply, to prevent the spike that can blow the Regulator Transistors. (when you turn the rig off, you will hear the fans keep running as the smoothing capacitors gradually discharge)

    But the other benefit is stopping both the heat sinks from getting hot in the first place.

    Get 24V fans (readily available on eBay) - I originally wired two 12V fans in series, but they end up running at different speeds. 24V fans are quite happy running on 28V (after all, people run 12V fans on 13.8V all the time) But if you want to slow them down, just fit resistors in series.

    Sorry, never took any pictures ! But the back of the rig looks very neat with the new fans.

    Oh and the same Mod is worth doing on the TS940 too !

    Roger G3YRO
     
    Last edited: Feb 4, 2020
  10. N8YX

    N8YX Ham Member QRZ Page

    My original didn't fail but did run quite warm, as did the rest of the radio. I went with the 26A Quint unit - it's the model Craig is currently shipping with his 930 kit.

    This one has good headroom and doesn't sag under load. Additionally, the radio is lighter by several pounds.

    I have the OEM transformer//regulator assembly in a box. If anyone reading this wants a spare OEM PSU, PM me.
     

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