New to this-8080DB Repair

Discussion in 'Exclusively Sansui' started by gopernoper, Sep 3, 2018.

  1. gopernoper

    gopernoper New Member

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    Hello everyone-
    My name is Will. My friend recently got me into vinyl, and as such have been looking for new gear to use with my turntable (Technics SL-BD27). Anyways, I found a Sansui 8080DB that was in our cottage. I was very excited about it, as I had read they were excellent receivers. But of course, there are some issues with it. I know this has probably been asked many times on here, but I need to know how to get it working, and if I can't where can I get it repaired. Something to note- I am 16. I don't have deep pockets, more empty pockets.

    Firstly, when the receiver is powered on, the Protection light flashes red continuously. It does not turn green or stop at any time. It is my understanding that it is required to check the driver board and replace some of the components. Where can I find the replacement parts/ how can I check these?

    Second, I am not sure if the Dolby Board is good in this particular receiver, I cannot test as the protection light will not turn green. Is there a way to test it in its current condition? I am aware of the repair process, and would care to avoid undertaking it. I am not new to soldering, but I do not have the experience working with this sort of components/hardware. I do not have the proper tools to work on a soldering job like this. If repair is unavoidable, is there a replacement available?

    Thanks for bearing with me.
     

     

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  2. slimecity

    slimecity Super Member

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    Where do you live Will?

    There could be other members who live close to you who may be able to help you out in person.
     
  3. gopernoper

    gopernoper New Member

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    Hey,
    I live in the southeastern corner of Wisconsin. Not far from the IL border.

    Anything I can check easily without heavy disassembly?
     
  4. avionic

    avionic " Black Knights " Subscriber

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    Not until you get the driver board squared away and get a green light and relay click.
     
  5. Hipocrates

    Hipocrates Anti-Muppet Subscriber

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    Hi Will, welcome to AK.

    First you will need to address the fuse resistors on F-2426 board. That board usually needs work.
    Do you have a DMM, the service manual a soldering iron?
     
  6. avionic

    avionic " Black Knights " Subscriber

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    Sounds like you need to find a service tech..
     
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  7. Markoneswift

    Markoneswift Quartz locked n ready to rock

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    There are tons of threads here on AK and on the wider inter webs about this very issue. It going to be components level repair time I would say so time to warm up the iron :)
     
  8. danrclem

    danrclem AK Subscriber Subscriber

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    Someone correct me if I'm wrong. If you pull the driver board out which isn't hard to do and it comes out of protection then the fused resistors are probably bad. There could be other things wrong too but this is a good place to start. You probably need to build a DBT to hook to it when you power it up. Do a search and you'll find out how to build and use one.
     
  9. nabeelsayegh

    nabeelsayegh AK Subscriber Subscriber

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    Will...There can be a number of things that will cause this guy to go into protection mode and stay there. I will tell you that your focus should be on the driver/power output section. The system is seeing something it does not like....such as DC voltage at the output. I personally like to isolate the problem by checking the main power supply feeding the amp section and ensure nothing is out of whack there. In fact, if you can disconnect the main power feed to the amplifier, the relay should kick in....that will tell you exactly where your issue is (relatively speaking). This may be an issue with your main output transistors on one of the channels. If you have a tester, I would try and pull each and test them individually out of circuit. That should not take too long. testing in circuit can sometimes lead to inconclusive results or false positives/failures. When it comes to the driver boards, check the pre-amps and biasing transistors as well as the emitter resistors (the big ones) next. You can do differential comparison testing between components on each of the channels. They are mirrored and should have a pretty close reading on both sides. What you are looking for is a reading the would NOT be anywhere close to what you would expect. Long story short, you should work your way backwards from the main outputs and see what you can find.

    I am actually located in Joliet, IL. It's a bit of a drive from the Wisconsin boarder, but if you did want someone to look at it and you are not able to identify things yourself, I can help you out....just shoot me a PM.
     
  10. gopernoper

    gopernoper New Member

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    Yes, I have a PDF of the service manual, a Soldering iron (adjustable temp) and a digital multimeter. Not familiar with all the functions on the meter, mainly just the continuity check and Ohms.

    Woah! 75% of that is Greek to me. I’d love to have some help looking at it but Joliet is quite a drive, especially because school is starting. Maybe if I have a free weekend and the repair is beyond me. I’ll keep it in mind. Thank you for offering. I may need the help in the future.


    In terms of the f-2426 board, that is the vertically mounted board towards the back of the machine? I had the cover off today just to take a peek.
     
  11. gopernoper

    gopernoper New Member

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    This is a picture I took today, I have circled what I believe to be the f-2426 board. Someone please correct me if I’m wrong.
     

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  12. Hipocrates

    Hipocrates Anti-Muppet Subscriber

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  13. Markoneswift

    Markoneswift Quartz locked n ready to rock

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    Good luck with this, watching with interest
     
  14. dr*audio

    dr*audio Fish fingers and custard!

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    Does your high school offer an electronics course? It would be a good idea to take it so you can learn some electronic theory and then understand what you're working on.
     
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  15. gopernoper

    gopernoper New Member

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    Not that I know of. I may ask around the shop classes and see if there’s anything they can do. For now I’m on my own. School starts tomorrow, so I can ask then.
     
  16. gopernoper

    gopernoper New Member

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    Morning all,
    First thing I did today was open up the case. Successfully removed the bracket and F-2624 board. I have included a photo. It is my understanding to check the fuse capacitors in each lower corner of the board, will be doing so. Something else to note, when I removed the board I plugged in and tested the receiver, I got the click and a green protection light. Also, I know these need to be replaced with 1/2w 180 Ohm fireproof resistors. Could someone link me a page where I can find them? Thanks.
     

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  17. gopernoper

    gopernoper New Member

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    Ok, next update. Tested both resistors, both are showing Open Link on my multimeter. In a bit I’ll remove them from the board and test again to be sure. Seems I’ve found the problem, now for fixing it. Is there anywhere that still sells capacitors like these? Not sure if there are any radioshacks left by me, probably not.included pictures of the test.
     

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  18. Hipocrates

    Hipocrates Anti-Muppet Subscriber

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  19. gopernoper

    gopernoper New Member

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    I don't have a local electronics store unfortunately, so I'll have to wait for the mail. Darn. I've never used a website like this, is the part number listed in the service manual? I need to know i'm getting the correct ones, don't want to make a rookie mistake.
     
  20. gopernoper

    gopernoper New Member

    Messages:
    19
    Hang on, did a quick google search and found this website- will the first listed set of the F-2624 driver board set work? I know it's a lot for only two needed parts but I need to know I have the right stuff.
    http://www.qrxrestore.com/parts/
     

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