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  1. Zekeman

    Sansui AU-7700 motorboating at max treble setting

    Well I determined this fact tonight: I happen to have an all-original F-2095 board in my circuit board bin so i swapped it out…result=SAME problem! So the issue must be in the F-2096 board.
  2. Zekeman

    Sansui AU-7700 motorboating at max treble setting

    Yes - That series of amps perhaps.
  3. Zekeman

    Sansui AU-7700 motorboating at max treble setting

    The replacements are common: A726 replaced by A992's and the C1313's replaced by C1845's. I have restored many similar amps with same. I do plan to pull each and retest though as I am making no progress.
  4. Zekeman

    Sansui AU-7700 motorboating at max treble setting

    Good evening. No joy on this issue. Here is a link to a video demonstrating the problem.
  5. Zekeman

    Sansui AU-7700 motorboating at max treble setting

    Well this gent seems to have identifies a solution. https://audiokarma.org/forums/index.php?threads/sansui-au-6600-little-amp-which-gave-me-big-kick-in-the-bottom.969915/
  6. Zekeman

    Sansui AU-7700 motorboating at max treble setting

    Another question for the professionally-trained techs here: give the fact that each of the few voltages on these two boards (f-2095 and 2096 ) testOK, what then does the troubleshooting process look like? I have been pulling and measuring components in the treble circuit and so far all ok. Any...
  7. Zekeman

    Sansui AU-7700 motorboating at max treble setting

    Issue still exists. IF I touch either of the two resistors (circled for each channel) or the base of either transistor, the hum disappears. The hum is present with the tone and filter switch in the tone and filter down position…and The high filter is in the “out” position. if I move the high...
  8. Zekeman

    Sansui AU-7700 motorboating at max treble setting

    It appears this amp is sensitive to that. Last night I cleaned off lots of flux around points on the tone pot board and cleaned with denatured alcohol. That seemed to help but I’ll reserve judgement for now until further testing. Yes I have noticed the shaft couplers.. They have their own...
  9. Zekeman

    RIP Terry DeWick

    Well this is very sad news. I never knew him personally but his reputation was top notch. Rest In Peace and condolences to his family.
  10. Zekeman

    Sansui AU-7700 motorboating at max treble setting

    Question for some of the expert techs here: do the tone and switch board as well as the volume pot and loudness switch boards use the chassis (metal chassis front plate) for ground? I ask because when I test the process with the boards UNmounted to the front chassis plate it will hum when I...
  11. Zekeman

    Sansui AU-7700 motorboating at max treble setting

    I've never had it on a 7900-series amp yet this is, I think, the third 7700 where I've had the/similar issue. I'm still at it. I rewired all the interconnects between the tone and switch boards. It sounds like some type of improper ground situation but I really don't know. I had it working...
  12. Zekeman

    Sansui AU-7700 motorboating at max treble setting

    Well I spoke too soon on that one. It’s back! Back to troubleshooting.
  13. Zekeman

    Sansui AU-7700 motorboating at max treble setting

    F-2096 interconnect wire (point 57) to the tone pot board was the culprit here. It appeared to be connected, I resoldered and then heard a hum and discovered it had broken loose.
  14. Zekeman

    Sansui AU-7700 motorboating at max treble setting

    Replaced all small trannies on the tone and associated switch board and the problem persists. I have had this exact problem before (several years ago) and cannot recall what was the solution. Later I will post a link to a video of the phenomenon for clarity.
  15. Zekeman

    Sansui AU-7700 motorboating at max treble setting

    AU-7700’s are finicky. I have run into some issue with almost all that I have restored. I’m currectly recapping one and have the loud popping at treble pot position at 3:00 o’clock. Only the 10 caps have been replaced on the tone pot board-super simple-but here we are.
  16. Zekeman

    Sansui BA-2000 filter capacitor replacement

    Correction here (4 years hence) - I sent the link to 10,000uf caps. I used 15,000uf in my BA-2000.
  17. Zekeman

    Sansui BA-2000 filter capacitor replacement

    Correction here (4 years hence) - I sent the link to 10,000uf cap. I used 15,000uf in my BA-2000.
  18. Zekeman

    3/23/24 - 1PM Northern Chicago/Southern WI Get-Together?

    Collette - does this look familiar?
  19. Zekeman

    3/23/24 - 1PM Northern Chicago/Southern WI Get-Together?

    Sounds great Bob. I will bring some type of Sansui component. Can’t wait.
  20. Zekeman

    Sansui 5000 - Building F-6013 Boards

    I am not bonzoro.
  21. Zekeman

    Sansui 5000 - Building F-6013 Boards

    Good to know. Thank you!
  22. Zekeman

    Sansui 5000 - Building F-6013 Boards

    I received the boards and populated them with the devices specified on the boards themselves. I have never built a board from scratch so this was pretty fun. Installed adjusted and the receiver sounds great and is running very cool.
  23. Zekeman

    Sansui 5000x install new F-6013 Boards help

    Well as it turns out the boards did not end up working for me. During testing I let the receiver run for a couple hours and when I returned to the bench the heat sinks were extremely hot (bias was set at 23) and there was no output. DBT test displayed bright light so some short was detected...
  24. Zekeman

    Sansui 5000 - Building F-6013 Boards

    Very good. Thank you!
  25. Zekeman

    Sansui 5000 - Building F-6013 Boards

    Good afternoon. I will be building a set of F-6013 boards for a 5000 (not A or X). The blank boards show transistor in position TR801 to be a MPSA18 which is not a very common device. Another thread shows KSC2383 as a good candidate for this position. Any advice on which would be the better...
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