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  1. Trnsfmr_Jr

    Sansui 5000A Goodwill Find!

    Hey Milo63. Just used this method to replace a faulty MPL in a 5000A. Worked great. Thanks for the solution. Just wanted to chime in and say after using my decade box I ended up using a 170k ohm resistor for R255 and adjusted the muting from there. My guess is the range would be like...
  2. IMG_20190416_163906

    IMG_20190416_163906

  3. IMG_20190416_164014

    IMG_20190416_164014

  4. IMG_20190416_164039

    IMG_20190416_164039

  5. Socket and Nuts

    Socket and Nuts

    Socket and Nuts
  6. Trnsfmr_Jr

    QRX Restore....anyone used them before?

    Hey! I remember that unit! The case looks great. So the adjustment is very similar but not exactly the same because the driver board is different. It is the same for the 990Db/9090db however. For the 9090 the 22ohm resistors will have been in the place of stock 22ohm resistors on R13-R16. Same...
  7. Trnsfmr_Jr

    QRX Restore....anyone used them before?

    Hey there, Justin here, Jim's son, owner operator at QRXrestore, and the one that has done most of the recapping/soldering since we started some 7 years ago. Just gonna pop in on the dolby bypass. I take the signal at the inputs to dolby circuitry, run it through the tape selector switches...
  8. Trnsfmr_Jr

    Working on a KA-907- Got Substitutions?

    Thank You. Tried these TRs and it seems to have been the culprit. Had it playing for 3 days now and no problems. Found the TRs on digikey. Thanks again, seriously, Justin
  9. Trnsfmr_Jr

    Working on a KA-907- Got Substitutions?

    Ya already got the black flags and the electrolytics. I get an intermittent distortion on the left channel. On the scope it looks like I'm losing the negative side of my sine wave- something like a missing voltage to a TR or a TR intermittently going bad. I got lucky one time and was able to see...
  10. Trnsfmr_Jr

    Working on a KA-907- Got Substitutions?

    Working on this real jerk of a Kenwood. Great amp but it suffers from a VERY intermittent problem. I can get it to crop up once every 3-5 hours for 30 seconds. Not even a consistent enough problem that I feel I could find it with freeze spray. Anyways- basically I've narrowed it down to some...
  11. Trnsfmr_Jr

    Sansui 9090: Original, everything works. Should I change anything?

    Yea. Those 22ohms down at the bottom left and right of the board- they change their production on those driver boards depending on whether they have those stand-off barrel fuses on the drivers. You may have one of the 9090s where they have already lowered the values of the fuses for the rail...
  12. Trnsfmr_Jr

    Sansui QRX-7001 Rebuild

    Hey there. If you'd like you could e-mail us over here at qrxrestore.com and we can make you up a recap kit using nichicon finegold for the audio path. That'll definitely be a bit more expensive than if you just go ahead and do the leg work yourself however. As a general, but not absolute, rule...
  13. Trnsfmr_Jr

    Guidance on 9090db problem.

    Unfortunately without a scope this problem is going to be slightly difficult to diagnose but you can still switch source wires to try to narrow it down. You could try switching the inputs to the dolby board. A blue and grey wire going into the bottom of the dolby board. If that doesn't switch...
  14. Trnsfmr_Jr

    AU-11000 Popping in right channel

    If the sound persists after disconnecting the pres and mains as Hyperion says I would look towards TR02, and TR04 on your driver board. Unfortunately however an intermittent pop won't usually show up as a bad TR on your MM. I would just use a couple KSA992 to replace the 2SA847 that come in...
  15. Trnsfmr_Jr

    Sansui 9090: Original, everything works. Should I change anything?

    Haha, of course not. I have just fixed over 200 F2624 boards, and over 150 F2436 boards. I've never seen one of these fusibles "save" a section of this amp. I believe that many of them are handling very close to a 1/4 watt already and that is why they go out of spec rather than actually...
  16. Trnsfmr_Jr

    Sansui 9090: Original, everything works. Should I change anything?

    I use a 1/2 watt resistors and lower the fuses from 10A to 6A or 7A for a little added protection. In my opinion these fusibles never did a great job of protecting these boards, they often just go out of spec instead of acting as a fusible. This can cause a whole host of other problems. If...
  17. Trnsfmr_Jr

    Sansui AU-999 DC problems?

    It is a 3A rectifier with a 4A fuse on the main AC line. Given that the voltage outta the transformer is something close to half of the voltage at the AC input and therefore something close to twice the current of the AC input (not including the other taps and assuming 100% efficiency- napkin...
  18. Trnsfmr_Jr

    Sansui AU-999 DC problems?

    Haha, I think it just takes one amp committing suicide and then you start to really hate them! Don't mean to sound wound up, just enjoying talking shop. I'd enjoy your write up. That's kinda what I was saying. Only way to test them is by hooking up an adjustable PSU. I guess a 9v might work, I...
  19. Trnsfmr_Jr

    Sansui AU-999 DC problems?

    Thank you everybody for being so welcoming! I also learned a lot from my dad (HI HI as he put it). So do you leave em in there untested? How do you know the speakers even are protected from DC? I mean you can check the diodes and transistors on there with a MM but that isn't 100%. Someone...
  20. Trnsfmr_Jr

    Sansui 9090: Original, everything works. Should I change anything?

    Board is mirrored too, you can even put it in backwards if you want and it will still work. Pretty handy for trouble shooting sometimes. Truth is that you probably won't get a ton of time out of this amp without doing all the caps and fusibles, but as long as you replace those fuses you won't be...
  21. Trnsfmr_Jr

    Sansui AU-999 DC problems?

    Thank you for the kind words about my pops. I feel that in most situations these days you're better off saving your ~$1000 restored amp than maybe saving some speakers. Also shorting the outputs will often take a lot more with it than just the outputs. The 999 could use a slightly beefier...
  22. Trnsfmr_Jr

    I Speak Sansui

    I Speak Sansui
  23. Trnsfmr_Jr

    Sansui 9090: Original, everything works. Should I change anything?

    Protip: On your power supply board there are 4 fuses right under the driver board. Check and see if those are 10amps- if they are change em out for 6A or 7A. If you choose to not restore the amp, that just may save you a lot of headache further down the line. Those 10A don't blow with a shorted...
  24. Trnsfmr_Jr

    Sansui AU-999 DC problems?

    Hey! cool to see that mod getting done! Yea I was just going to chime in on the protection circuit on these models. It is garbage. It will save your speakers by shorting the outputs of the amp. I cut all 3 wires that go to the protection and cap them with heatshrink. The DC drift on power up...
  25. Trnsfmr_Jr

    Sansui 9090DB noisy/dirty sound before and after cleaning pots

    You absolutely sure that FM doesn't scratch too? Doesn't make much sense because Phono inputs and FM all go into the dolby board on the same two wires on the bottom of the dolby board. Grey and Blue wire on the bottom of the dolby switch board. Besides the phono preamp those inputs see the same...
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