Bit of an intro and 8080DB "resurection"

Discussion in 'Exclusively Sansui' started by tourmax, Jul 17, 2018.

  1. tourmax

    tourmax New Member

    Messages:
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    (Edit: Dang, missed and "R" in resurrection!)

    Hello all.

    Been getting back into HIFI over the last while and have developed an affinity for Sansui ever since getting my Sansui 350. Sounds great and looks just right to me. Paired up with a Technics SL2000 and some AR-4x's it sounds fantastic. Snuck a pioneer CT-F750 in there for my old cassettes just because (and there may be a modern 5 cd carousel Sony CD player hidden in the room somewhere too). Toss in a set of Sansui SS-35's and Pioneer Monitor 10 headphones and I'm just about set up for any listening I want to do.

    If you haven't guessed yet; I prefer "vintage" for audio stuff.

    But I've been keeping my eyes out for one of the bigger Sansui units. something 880/9090-ish. But that stuff is near impossible to come by around here and if you do, they want the moon for them. The other option was buy one online, but you'd pay more in shipping than you pay for the unit!

    Then, one day on a whim, I tossed a "wanted" on the local facebook audio page to the effect of wanting one of the larger sansui's, working or not; 8080, 9090, etc. A guy about an hour or so away replies that he's got am 8080DB that has been popping fuses and a QR-1500. I get there and he leads me down into the basement "rec room".

    He's got a hodgepodge of audio stuff: reel to reel, pioneer, akai, and some less common brands. 70's and 80's stuff. Some working, some not. Some hooked up, some not. He's a pretty heavy smoker and everything has that "brown" layer on it. Meh, to each their own, but it sure isn't helping his gear any....and the longer I'm in there, the sicker I get....two days afterways I still feel sick to my stomache....

    I try to get some of it working for him, but can't do much without my tools handy other than look for burnt or obvious things.

    Then we pull out the 8080DB and he pulled the case off. It's in pretty hard shape. I'm not sure how long he's had it, but it's covered in cig smoke/tar, inside and out. The case has rust spots on the insides and so does the transformer case. the aluminum/pot metal bits are all corroded, although it's mainly cosmetic (no pitting...yet). It's missing screws, things are cross threaded and the hold down piece for the power board is missing. It's been thoroughly messed with and looks like it might have spent time in an outside shed or (lord forbid) time at the curb in the weather. But the silver front is all there, the clear plastic is in decent shape and the silk screening all seems intact (under that "brown" layer).

    He starts putting fuses in the protection board and the pop over and over. He then starts going bigger and I'm getting ready to leave as fuses start popping elsewhere on the board and it's getting more and more likely I don't want to bother with what else is beginning to get fried.

    But then he gives up on the fuses and we start talking turkey. He wants way more than what I think it's worth, especially with problems. I know it's all fixable, but how much is it going to cost me? We settle on 260 Cdn and I'll take a couple of his pieces home to see what I can do for them.

    I load it all in the truck thinking I'm stupid as the day is long and I just paid waaaaay too much for a busted and beat up unit. But it is a Sansui,it is an 8080DB and it is (I hope) salvageable. Toss in the "nearly impossible to find" element and I pretty much had to take it. I'm also a sucker for hard luck cases and I felt this ol' girl needed me to save it.

    I don't even get halfway home and I have to stop and unload all the gear to the bed of the truck. Thankfully, it's sunny and dry out. I can't even be in the same cab as the stuff, it stinks that much. I'm not a smoker, so it's really turning my stomach. Sucking smoke for the last 1/1.5 hours isn't helping either. Actually, my skin is beginning to feel really bad at this point and I figure it's all the smoke I was moving around in. Stuff goes in the garage when I get home, clothes go straight into the washer and I go straight into the shower for a serious scouring.

    Later, I head out to the garage with a bottle of lysol wipes. A quick cleaning on the outside reveals it's not too bad, at least not where it counts (cosmetically). I grab a can of contact cleaner and liberally spray the interior, watching brown liquid run out the bottom of it and stain the plywood I had it sitting on.

    I pull the power board and plug it in. No fuses popping. Power board in; pops fuses but no protection mode. Seems like outputs are the likely culprit. I'll chase that down soon. I feel like chasing some cosmetic stuff right now so I can feel better about buying it, at least looks wise.

    I should have taken a few before pictures, but didn't think of it at the time. Suffice to say, it looked like pooh.

    The whole unit gets a good soaking and bristle brushing with isopropyl. The face plate comes off and I clean up the silver bits with my go to: nevrdull. Takes the tarnish and brown off and leaves the silk screen lettering in place, just don't go too crazy with it.

    The knobs and switches are disgusting. IPA and a good scrubbing gets them respectable. One of them looks like the unit has been dropped on it. The chassis and pots don't show any obvious damage, just the face of the knob. I'll replace that one in the future, but it will do for now. I coudl just spin out another one on the metal lathe, but buying a decent used replacement will just be simpler.

    The Headphone jack is all sideways cross-threaded, so I sort that out too. Basically have to use picks and sandpaper to rebuild the plastic threads enough to start the metal nut.

    The potmetal widow surround around the lens is just beat to crap. Corroded and flaking everywhere, like it's been outside in the elements. But that's easy; old paint just gets new paint. I use an "auto trim" black. Just dull enough with a hint of satin that pretty much matches the original Sansui paint job. Once cured, a little aggressive grit sandpaper and some careful sanding reveals the silver band in the black and gives it a similar "brushed" finish like original.

    The lens is actually pretty good after a quick clean, so i put it all back together to just see what it is going to look like.

    And it looks damned good! That classy 70's Sansui look is shining through again and I'm feeling a little better about spending 260 bucks on it, even if I still feel sick to my stomach (sick from smoke a full day later! Sheesh!).

    The wood case is really just a plywood with fake plastic woodgrain stuck on to it. It's beat up pretty bad and looks like Pooh. Big steaming piles of pooh.

    I thought about re-using it by stripping it and using wood veneer. Then considered just putting the fake woodgrain back on it and calling it a day.

    But this is going to be a keeper unit for me and probably a last one I intend to buy (yeah, famous last words). 85 WPC is more than I'll ever really use. So I think I'll just put the original cover away in storage and build a new case out of walnut or cherry. It's a pretty simple project for me to bang out in an afternoon (all I need in the shop to do the wood working). Something nice that will take a nice stain to look like the original, but in real wood instead of fake.

    That about catches us up to today. Next up will be chasing down the electrial faults and a bit more cleaning/painting of components.

    Once I get it looking respectable and at least working to the pint where I know I'm not throwing money away (err...I guess I mean more money), it will be time for re-capping and such. Eventually, it will get to a total restore job, maybe even better than original but still looking and feeling like a classic Sansui.

    :)

    fr_3768.jpg fr_3763.jpg fr_3764.jpg fr_3755.jpg fr_3756.jpg fr_3760.jpg fr_3761.jpg
     
    Last edited: Jul 17, 2018
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  2. AlTinkster92

    AlTinkster92 AK Subscriber Subscriber

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    Heck I've seen worse, a properly working 8080DB is a nice sounding unit so don't give up. I've had mine for 12 years and other than getting he switches cleaned it's still bone stock. Do a little at a time and eventually you'll have it up and running. Good Luck with it! :) Al

    PS, lots of great help in here so don't be afraid to ask plenty of questions!
     
  3. tourmax

    tourmax New Member

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    44
    Haven't gotten in to it very deep yet, but did a little more fooling around this morning trying to get an idea of where to focus my attention first (other than the popped amp section that is).

    I pulled the pre out jumpers and routed the pre outs to an exterior amp. Yep, got sound! That makes feel a little better!

    But, I think I have an additional problem in the Dolby board. The right channel is good and strong, but the left channel is half strength the right or worse. Turn the Dolby board on (FM Dolby) and it gets even worse. Right channel gets stronger, left channel turns in to almost a whisper.

    So it seems I'll have to go through the Dolby board.

    Great.

    I was hoping not to have to go through that. Hopefully its just a board passthrough that needs to be re-flowed....
     
    Last edited: Jul 18, 2018
  4. LBPete

    LBPete Rolling Along Subscriber

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    Before condemning the Dolby Board, clean the Dolby switches. It's hard to see from the pictures but it looks like it has the later driver board that uses bias diodes. Can you post the serial number for the Database?

    - Pete
     
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  5. tourmax

    tourmax New Member

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    Will do.

    You already have the serial number from my "popping fuses" thread.

    ;)
     
  6. LBPete

    LBPete Rolling Along Subscriber

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    Sorry, I didn't realize this was a continuation of your earlier thread.

    - Pete
     

     

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  7. tourmax

    tourmax New Member

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    Heres the driver board in closer detail:

    C6E63558-8FE2-4C16-AB05-925435A9FA03.jpeg
     
  8. tourmax

    tourmax New Member

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    44
    no worries.
     
  9. LBPete

    LBPete Rolling Along Subscriber

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    Interesting. It has the bias diodes but the older chassis plating. The driver board is all original. At a minimum It will need to have the fuse resistors replaced. There are many, many threads on that topic. Use the forum search function to find them.

    In the other thread you said it was popping fuses, here you say its working but has channel dropout. What happened with the fuses?

    - Pete
     
  10. tourmax

    tourmax New Member

    Messages:
    44
    Well, just becuase it was in the unit doesnt mean it was born with it. The hold down/shield is missing so someone has been rumaging around in there before i got it.

    Don't know on the fuses, I got it this way. I think there's a couple things going on here:

    1. The power board pops fuses f01 and f02 as soon as you turn on power. Remove the driver board and they still pop with power on. Seems to point me to blown outputs.The guy trying to sell it to me kept putting bigger and bigger fuses in F01/2, trying to get it to work. He eventually started blowing fuses elsewhere on the power board. It was still his receiver at that point so I was letting him go, but was getting ready to walk away when the smoke came out of something that wasn't a fuse. Thankfully, he gave up before (hopefully) any further damage was done. He said it was working fine until his buddy spun the volume knob from off to full on in a split second....and then....POP! I wonder what happened there now.......o_O

    2. I pulled the jumpers and sent the pre out to a separate amp and got sound from both channels. But left channel is half or less power than the RH with the Dolby selector to "OFF". When I switch to "Dolby FM", the channels get a little clearer/louder and the meters reflect the same power difference: RH jumps with signal, LH almost flat.

    I did notice something else while playing with the Dolby selection: If I go "REC-1", I get what sounds something like a 1-10 KHZ tone on the RH channel and meter deflection to about half, but no tone or deflection on the LH channel. Switch to "REC-2" and both channels are silent. I have nothing hooked up and monitor switches are "off". I've got no previous experience with the 8080/9090, but that behavior just doesn't seem normal to me. Could be the Dolby switch I suppose, but I'm thinking it looks more and more like I'm going to have to get into the board....yeesh. Was really hoping to avoid that.....:(

    I metered the resistors and they came up good, but they will get replaced anyways, along with a recap. I'm waiting for a de-soldering gun I ordered to show up. Too many joints to do with a wick and/or sucker. Well, I could, but I'd go nuts after a couple hours of that....lol! I'm also waiting to build up an order list so I don't get dinged with crazy multiple shipping charges....
     
    Last edited: Jul 18, 2018
  11. tourmax

    tourmax New Member

    Messages:
    44
    Went hunting for chassis screws today. Theres sonething like 12 in the bottom plate and it had a grand total of two.

    Yes, you read that right: TWO!

    I tried a couple bolt specialty places. No joy. I went to several brand chain hardwar stores. No joy.

    I was being very picky on what i was going to use: had to be same size, pan heads and phillips. Same gold-ish color plating if possible.

    Juat when it looked like i was going to have to settle for silver plated “close enough” screws, I ran across a clearance bin at home hardware. In it were sone picture hanger brackets. Two packages for 0.50 to be exact. They had 5 screws in each. Looked to be the right diameter and they were gold plated.

    6DF76FF1-5095-4A86-9A34-342D1132E518.jpeg

    Just enough to fill all the missing spots!

    I get them home and theyre a little too long and sharp pointed. Quick pass on the grinder fixed that right up.

    Popped them in the case and they look the business!

    4AF955FC-C875-4313-A463-56B54EC53440.jpeg

    Was also missing the small countersunk screws at the top of the front bezel. Rooted around in my spares bin and pulled out two perfect length countersunk screws, proper thread too. What are the chances of that?

    Good day. Tomorrow i start sleuthing out the electical issues...
     
    Last edited: Jul 19, 2018
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  12. tourmax

    tourmax New Member

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    Need a bit of a double check of my work on the power transistors. Its been a while since I've had to check something like this.

    Pulled them out of the rig (L to R, 1 to 4 as viewed from the rear of the machine):

    fr_3778.jpg

    and metered them with my BK Precision 388b on diode test:

    fr_3777.jpg

    Results:

    #1 (2SC1116)

    collector neg to emitter pos- open
    Collector neg to base pos- 0.520
    base neg to emitter pos - 0.520
    base pos to emitter neg - open

    #2 (2SA747)

    Cneg Epos = open
    Cneg Bpos = open
    Eneg to Bpos = open
    Epos to Bneg = 0.520

    Actually, I think I did that wrong and the 747 is pnp instead of npn, as collector pos to base neg shows 0.520 and collector pos to emitter neg shows open. Or maybe I've got that backwards which in non and pnp. Like I said, it's been a while and my brain isnt' as sharp as it used to be....

    So, #2 with "reversed polarity" checks:

    Cpos Eneg = open
    Cpos Bneg = 0.520
    Eneg B pos = open
    Epos Bneg = 0.520

    Now that seems to make more sense! Carrying on....

    #3 (2SA747):

    Cpos Eneg = short
    Cpo Bneg = 0.145
    Eneg to Bpos = 0.145
    Epos to Bneg = 0.145

    Yep, that one looks like toast. Crumbling, crispy, black toast!

    #4 (2SC1116):

    collector neg to emitter pos- Short
    Collector neg to base pos- 0.290
    base neg to emitter pos - 0.700
    base pos to emitter neg - 0.289

    So it looks like # 3 and #4 are blown and #1 and #2 are still serviceable.

    But like I said; it's been a long time. Does that sound correct from those meterings?

    And I guess the next question is should I get some used take outs or, since I understand they are discontinued, look for modern alternatives?

    Forum search seems to indicate to go with 2SA747 → MJ21193 and 2SC1116 → MJ21194 form mouser. Sound correct? If I go new, I will be replacing all 4 for sure.....
     
    Last edited: Jul 19, 2018
  13. LBPete

    LBPete Rolling Along Subscriber

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    Yup, that's the tricky bit about trying to track production changes. It simply means we need more serial numbers to better identify trends.
    OK, now I understand, you separated the preamp.

    What chassis screws are you looking for? The machine screws holding switches to the chassis are 3mm metric but most of the chassis screws are a self tapping "sheet metal" screw. They are impossible to find in metric. The only good way to match them is from a donor unit.

    As far as the blown outputs, be sure to check the driver transistors and related components on the driver board.

    - Pete
     
  14. tourmax

    tourmax New Member

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    3
    I’m actually thinking I might just go “all in” right away, pay the money and do everything right off. Caps, resistors, transistors, etc. That way it sill outlast the time I have left in this world.

    There wouldn't happen to be a parts list anywhere for an 8080DB “rebuild” would there?
     
  15. Hipocrates

    Hipocrates Anti-Muppet Subscriber

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    I think you did good with that unit, after some work it will give a very nice sound.

    Not parts list ''per se" but those units are perhaps the most documented Sansui ever.

    For the outputs you can put MJ21193/94

    Caps...just replace with whatever value is in there. Nichicon PW for filtering and decoupling
    Wimas for smaller thank 4.7uf (5mm lead spacing)
    Nichicon KT, KA or Elna Silmic II. are good choices too.

    Fuse resistor replacements.
    Metal Films 1% 1/2W will do.

    Check for tnsilver threads on this units, they are gold. And this unit is almost the same than the 9090db.

    Finally just ask if you need something, a lot people willing to help.
    First lets do the power supply section, then service the driver board, then the protection board, and last the preamp section. This approach works for me.... maybe you will feel comfortable working that way.
     
  16. tourmax

    tourmax New Member

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    There's a 9090DB list here from tnsilver: http://audiokarma.org/forums/index....90db-any-recap-rebuild-list-available.703330/

    Now, that's for a 9090DB, but a quick check of my 2624 board seems to match up to the list. There will be some differences for sure (like the number of outputs), but I think this might cover it all (or at least 90%) without having to spend hours squinting through magnifying spectacles, scribbling down part numbers and then trying to match equivalents for discontinued/obsolete parts.

    Thoughts? Opinions on that list?

    For right now, I think I'm going to do the driver board and power supply as well as all 4 outputs. That should at least get it up and running and point me to the areas that need attention next. Will also spread costs out a bit to make it an easier swallow. Whichever way I go, I'm shooting to spend at least a hundred Cdn in order to get the free shipping option from mouser. I figure just the 4 outputs will put me over the hundy mark...
     

     

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  17. CDFixer

    CDFixer Number 1 USC Trojan Fan Subscriber

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    Just a couple of notes. the bottom screws originally were black.

    From your original post you Quoted.."

    "Green ribbon cabling and fuses on the protection board. Not sure if all the fuses are OEM (or added before left factory) as some of them have those little white stickers with amperage and voltage underneath them"
    All the 8080DBs had the little white stickers under the fuses. The power supply boards were silk screened for the 9090DB which used different fuses, Hence the stickers.

    I have never seen an original unit with bias diodes, with green ribbon and fuses on protection board.

    The right most button is above the dolby switch is the Dolby Cal button/power meter button. When out the meters monitor the output power. When in pressed the meters become Dolby cal meters. In this mode when in either of the REC modes 1 or 2. A Dolby test tone is sent to the amps and the tape outputs. You should have an output on both channels either mode. The meters should come to rest in the middle of the Dolby Double D on the meters (straight up).

    As LBPete said they are impossible to find. The closest that I have found is a #5 type 2(has a flat end) the head is same size and #2 Phillips. They are slightly larger thread diameter The 3mm are nominal .1181" Dia #5 is .1280" a difference of .0099 or 1/100th of and inch. I find these to work well as you can get them in black and yellow. the yellow is a different plating as Cadmium is now longer used as a plating.
    Another good thing is these screws will work in stripped 3mm holes.


    I have several of the hold downs for the driver board PM me if you want one.
     
  18. maxhifi

    maxhifi AK Subscriber Subscriber

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    You're on the right track, I just finished a 9090db with similar electrical issues, it's a great sounding receiver!
     
  19. tourmax

    tourmax New Member

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    Well, $165 Cdn later, all the bits are ordered for a the rebuild.

    :)

    I doubled up on the power transistors (IE: 4 of each instead of 2). Plan is to meter them and choose the ones closest in values and keep the others for spares. I figured it was worth it since my order was high enough to qualify for free shipping. Never hurts to have spares around either.

    I'm thinking I might just do wood veneer on the 8080DB case instead of making a new one out of oak. Just have to strip the much abused vinyl wood grain off....
     
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  20. CDFixer

    CDFixer Number 1 USC Trojan Fan Subscriber

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    When you "strip" the vinyl off you will find two layers a thin layer with the "wood Grain" and a thicker tan colored layer. the thin layer comes off easy the tan layer no so much. I have found that cutting it in 1 in (26mm) strips along the grain then pulling the each strip easiest. Don't try to heat it to soften the glue you will spend hours trying to get the glue mess off. after the tan part is off just lightly sand the case and fill any cracks or gaps. I pulled the vinyl off one case it had a nice grain pattern, I just stained it and coated it with satin polyurethane. Came out very nice. Also when installing the laminate, I just cover the holes and grate cover and cut them out later.
     
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