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Considering Purchasing a 990DB

Discussion in 'Exclusively Sansui' started by dpcornell, Apr 14, 2018.

  1. dpcornell

    dpcornell AK Subscriber Subscriber

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    Hello all!

    I have the ability to purchase a 990DB that powers on but the speaker protection light blinks.
    That being said, is the driver board likely the issue?

    I've read a couple threads, but I've got to email the seller back about purchasing it tomorrow. The wood case is rough and will probably need new veneer, but the faceplate looks good (albeit dirty). He wants just under $300.

    Anyone have thoughts on it?
    00707_lTj4VbtJdC6_1200x900.jpg 00c0c_cLnU1u7csx2_1200x900.jpg
     
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  2. DougBrewster

    DougBrewster AK Subscriber Subscriber

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    Let me have his contact details and I'll give you a free appraisal..
     
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  3. dpcornell

    dpcornell AK Subscriber Subscriber

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    Noted! Thanks for the input. Any ideas off hand where the problem might lie? Hopefully there wasn't a catastrophic failure.
     
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  4. DougBrewster

    DougBrewster AK Subscriber Subscriber

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    Probably driver board failure cascading into blown outputs. Don't know, don't care, just buy it or give me his address... I assume it's internally complete.
     
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  5. DougBrewster

    DougBrewster AK Subscriber Subscriber

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    To clarify a little bit. Catastrophic is a relative term; it probably is with a number of blown components and a few hours work for a competent tech. It's a very low asking price. You could spent $500 on getting it fixed on top of the purchase price and not be out of pocket. Course it depends how rough the cabinet is...
     
  6. Tom B

    Tom B AK Subscriber Subscriber

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    Many time, the protect light blinking issue is usually caused by the fusable resistors on the driver board have drifted way high out of tolerance, or have opened. Out of all of the Sansui's I have worked on or restored for others, 9 times out of 10, it just the resistors and not outputs and or drivers. That being said, there are 14 or 16 fusable resistors that will need to be replaced on that board. Those units also require cleaning of the protect relay contacts, usual rebuild of the tuner power supply, cleaning and deoxing of all controls and switches. Examination of all filter caps need to be done, with possible replacement of some as well as the low value coupling caps, but I have found that caps in Sansui 990DB, 9090DB, 8080DB etc hold up very well. There is a dolby board pair that may need extensive work to re-pin some connections as well.
    But for $300 you should jump on it immediately as its a great price.
     
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  7. DougBrewster

    DougBrewster AK Subscriber Subscriber

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    well there you have it dpcornell, an opinion from a hobbyist and one different and more detailed from a pro, Tom B. Did you buy it yet?
     
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  8. dr*audio

    dr*audio Fish fingers and custard! Subscriber

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    Assume that the Dolby board needs rebuilding since you can't test it. There are 40 feedthrus on the board that need to have a wire inserted through them, bent over on both sides and soldered. The wafer selector switch must be removed to do this. There is a flat flexible cable on the board that needs to be replaced with a ribbon cable because they go intermittent. If you are lucky, the problem with the amp may be just the flameproof resistors need to be replaced.
     
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  9. dpcornell

    dpcornell AK Subscriber Subscriber

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    I am just waiting on to hear back from the seller. I am completely sold and very excited! Thank you all for the responses!
    The dolby board doesn't seem difficult, only time-consuming.
    Once it is working, I'll shotgun the electrolytic capacitors. Do any of you know good rebuild threads off hand?
    I'm going to compile a list, since I won't have time to work on it until late May.

    Finally, what species of wood should I use for the new veneer?
    There a 990DB currently for sale on that auction site that has a gloss black case, which could always be an option.
     
  10. Tom B

    Tom B AK Subscriber Subscriber

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    Classic wood covering for the Sansui's is usually Walnut.
     
  11. kevzep

    kevzep Its all about the Music Subscriber

    300 bucks, totally worth it!!

    There's nothing that can't be fixed on that....It will probably fire up OK by simply replacing the fusible resistors on the driver board....

    Nice score!!
     

     

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  12. dr*audio

    dr*audio Fish fingers and custard! Subscriber

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    If you know which end of a soldering iron to hold, you should be able to CAREFULLY repair the Dolby board if needed. Here's a helpful tip:
    To get to some of the boards in the front part of the receiver remove the front panel, then remove the screws that hold the top part of the front chassis that supports the tuner and IF board and swing it up out of the way.
     
  13. DougBrewster

    DougBrewster AK Subscriber Subscriber

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    I've made four cabinets for 9090DBs and an 8080DB and after quite a bit of research the closest I've got to original is American Black Walnut. I bought pre-veneered 13mm plywood. Worked out well. Just be sure to seal the wood with shellac prior to gluing the joints. I did try re-veneering the original case but just couldn't master it..
     
  14. dpcornell

    dpcornell AK Subscriber Subscriber

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    Thank you all for the responses. It is currently sitting on my credenza. Sadly, I've got finals coming up so I won't be able to work on it until May.
    That being said, is there a consensus on fusistor replacement? Most of what I've found has suggested replacing all of them with metal film resistors. I'd like to get it running correctly before the capacitors get shotgun replaced.
    [Mods, if I need to start a new thread for this, please let me know]

    After it is singing again, I'd like to focus on the cosmetics:
    As for the veneer, it might be pretty darn cool to use purple heart.
    Does anyone have experience with repairing damaged faceplates?
    I've put some photos of the faceplate up. The left corner has a slight bit of damage. Should I just live with it or is there something I can do to make it look less obvious?
    (Forgive me for the dirty receiver, but I haven't actually cleaned it yet because I know that as soon as I do, I won't be studying for Commercial Law and Business Orgs...)

    Again, thank you for your help. I'm excited to hear how this will compare to my Marantz 2285 and my brother's QRX-6500!
     

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