Sansui 9090 Driver Board r

Discussion in 'Exclusively Sansui' started by IndyAudio, Nov 5, 2017.

  1. IndyAudio

    IndyAudio Active Member

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    Location:
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    I just picked up a clean 9090 from the original owner that was in protection mode. VU meters were only lights coming on. After checking the Sansui Forum FAQ, in 5 minutes, I was able to get my tuner dial and both tuner signal lights on by changing the red wire location. The posts also helped me diagnose the root cause of protection mode is from the driver board - removed it and flashing red changes to green light, out of protection!
    I got excited when I saw the fix for the 9090 DB board only involved changing the two outboard resistors, but this is not the case with the 9090 as there are many resistors here. I checked a few and they were out of spec or not providing even readings comparing left to right channel.

    I'm an amateur and don't want to F up my board, it's the later one with the fuses F2436-1. I can send pics.

    Does anyone here on the site work on the boards if I carefully packed it and mailed it to you? Thanks guys!
     
  2. eiraved

    eiraved AK Subscriber Subscriber

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    I’m pretty sure the driver boards for 9090 and 9090db are the same, and the fusible resistors on that board are normally the issue. It does appear the problem is with the driver board, since removing it takes the unit out of protection.
    Take a picture of the board and post it.
     
  3. IndyAudio

    IndyAudio Active Member

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    142
    Location:
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    Thanks, the FAQ here indicates the boards are very different. The DB has a couple of outboard fusible resistors that once replaced do the trick. Not so for the non DB model.

    Uploaded the board F 2436-1 with the fuses, believe these are the later version.
     
  4. eiraved

    eiraved AK Subscriber Subscriber

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  5. IndyAudio

    IndyAudio Active Member

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    Location:
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  6. IndyAudio

    IndyAudio Active Member

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    Location:
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    Yes, thanks very much, I did see that one. I have a perfect working 9090DB, but the board is different, otherwise, I'd swap and test it here.

    Another thread here for the 9090 points to about a dozen or so resistors that can be suspect. I can test them all but my skill in desoldering these in tight places on the board is what has me seeking someone to do this for me. I was all ready to do the job myself when I saw the 9090DB board and the location of the 2 resistors was easy to access. Not so much for the 9090, thank!
     
  7. eiraved

    eiraved AK Subscriber Subscriber

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    I didn't quite understand your response. Are you saying the board in the link I posted is a 9090db board, because it is a 9090 board. The difference is yours has an additional two fuses, which I would check first for continuity if you haven't already. Other than that, they should be identical.

    You are correct in considering sending the board to someone with good soldering skills to replace the components if you are unsure of yours. The traces on the Sansui boards are prone to lifting under excessive soldering heat, and that increases the chances of breaking one of them.

    While you're at it, you should also consider replacing all the old caps on the board. Also consider replacing all 4 VR trimmers with some Bourns trimmers for easier adjustment of offset and bias.

    FYI, the 9090db board has much more than two fusible resistors on the driver board, but the two you mentioned are the failure culprits 90% of the time. You should always replace all the fusible resistors with metal film resistors, since they are now old and even more prone to failing.
     
  8. LBPete

    LBPete Rolling Along Subscriber

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    First, the F-2436-1 driver board used in the 9090/8080 and the F2624 driver board used in the 9090DB/8080DB are completely different. Next, there are several variations to the F-2436-1 driver board. From the picture, it looks like you have a later production board. The fuse resistors are a light gray color. If you enlarge the picture, we can point them out to you.

    Also, please post the serial number for the database. Click on the link in my signature block.

    - Pete
     
  9. IndyAudio

    IndyAudio Active Member

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    Location:
    Indianapolis, Indiana
    Totally agree

    Thanks again, we are on the same page here.
     
  10. IndyAudio

    IndyAudio Active Member

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    Location:
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    Thanks Pete, I just posted my 9090 serial number. I have a 9090DB and an 8000 receiver, if I can access the serial numbers, I will post as well.

    Yes, agree on the boards and have seen some posts where the suspect resistors are pointed out, thanks. I'm looking for someone to freshen up this board for me, you perhaps? Thanks again!
     
  11. IndyAudio

    IndyAudio Active Member

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    142
    Location:
    Indianapolis, Indiana
  12. LBPete

    LBPete Rolling Along Subscriber

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    Servicing the driver board separately from the receiver is tricky Assuming there is nothing else wrong, it's easy enough to swap out the resistors but once that's done you still have to test it and set DC offset and bias current. That can't be done accurately without it installed in your receiver. To test it remotely, you need to have another 9090 that uses that same driver board variation and there is a risk of an un-diagnosed fault with the driver board damaging the output transistors on the test unit.

    - Pete
     
  13. IndyAudio

    IndyAudio Active Member

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    142
    Location:
    Indianapolis, Indiana
    Thanks Pete - I saw that nearly everyone replacing the two resistors on the DB board had success and it came out of protection mode. Was hoping for the same here with someone replacing them on this board. If it comes out of protection, I was going to try the rest of the adjustments. Just trying to avoid bringing it in to a tech here locally while learning a bit more about all of this at the same time, thanks.
     
  14. Binkman

    Binkman Addicted Member

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    As noted above.. if these are fusibles there are probably not many. if that solves your issues.
     
  15. eiraved

    eiraved AK Subscriber Subscriber

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    I defer to LBPete here, glad he chimed in! :bowdown:
    You've got some interesting speakers in the background there!
     
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  16. IndyAudio

    IndyAudio Active Member

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    142
    Location:
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    Thanks everyone - I am still looking for someone to check all resistors and swap out at least the fusible resistors on this board. I will take the rest from there afterward, thanks
     
  17. danrclem

    danrclem Super Member

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    I know you're wanting a local tech and a place as big as Indy should have at least one. Just in case you can't find one I've heard good things about Magnetic Tape in Louisville from a few people but have no personal experience with them. It would be easy to mail a driver board.
     
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  18. IndyAudio

    IndyAudio Active Member

    Messages:
    142
    Location:
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    Thanks, I will check them out. The local guys in Indy are so backed up, it's not worth the wait.

    I was really wanting someone from AK that is good with soldering and these boards that wants to earn a couple of bucks. Doesn't matter where they are located, thanks.
     
  19. eiraved

    eiraved AK Subscriber Subscriber

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    That's commendable of you to think of AKers first, but you'll find out quickly that most here who do this for a living (or a hobby) are backed up for months. I do restorations and I'm so backed up on my own projects that I cannot take on side jobs. You are probably better off taking danrclem's advice.
     
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  20. Hipocrates

    Hipocrates Anti-Muppet Subscriber

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    My board is the same than yours.
    Check this ones.(yellow circles)
    IMG_6988.JPG

    And check on the back for a broken trace.

    Too bad I'm so far away, otherwise I would give you a hand with the board, even when not ideal (as LBPete correctly appoints), sometimes a man got to do what a man got to do.
     
    Last edited: Nov 6, 2017
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