Restore + Repair Yamaha C-2a & C-80 / M-80

Discussion in 'Yamaha' started by mr.muddles, Aug 25, 2018.

  1. mr.muddles

    mr.muddles Active Member

    Messages:
    451
    Location:
    Portland, OR
    I've recently had the great fortune of landing all of these components within my budget.

    I know there is a lot of info about the M-80/85 and I've tried to read as much as possible. Mine was in protection when I got it due to the DSBG issues... fortunately, it was just the two zener diodes that were toast and everything else appeared to be okay. Cleaned everything up and put back together and no longer in protection. I ordered a full set of electrolytic caps Nichicon KZ, FG, and KW plus the one ES bi polar cap and then I got some new variable resistor pots. I haven't installed these yet cause I'm doing the preamp first.

    Right after I got my M-80 I went looking for a preamp. Ended up getting a Kenwood Basic C1 and then immediately after finding a C-80 listed as not working (no power).

    I got the preamp and took out the two heat shielded transistors with the glue and cleaned everything up. These two resistors had joints cracked so bad the whole thing was just wobbling back and forth rattling around. I took out a couple resistors nearby and cleaned those got all the glue cleaned and put new thermal grease on the heatsinks and put everything back together. Powered it up and everything sounds good, the volume pot is a little dirty. Phono sounded great. I ordered a full set of caps which I am installing now...the original power supply caps were about to explode I've never seen them like that... the ones in the phono power supply was bulged but not as bad... Nichicon KZ, FG and KW... although now I realized I missed a bunch of bi polar caps and ordered polarized ones instead so I'll need to go back and get the Nichicon bp ES versions... I think I will get some new variable trimmer resistor pots too -- wondering what else I should do if anything while I am putting in a parts order?

    Now, unbelievably, just the other day I landed a C-2a listed as not working... someone was trying to sell it with an M-2 and was going to include the C-2a for free with it because "it didn't work" but "might be an easy fix" ... well, I made an offer on just the preamp and they accepted. Got it home and haven't opened it up yet as I'm working on the M-80/C-80 and trying to finish the restorations on those first. However, I powered it on and ran a source through the AUX and it appears as though it just needs the volume pot cleaned but will need more testing (didn't test phono yet).

    I realize this is getting to be a long post but really what I am after is a parts list for the C-2a or a list of all the electrolytic capacitor values so I can put an order in and have my parts ready for next weekend to work on the C-2a. I can't seem to find one like is included in the SM for the C-80/M-80 which made putting my order into Mouser pretty easy. I would prefer not to make a list of caps by poking around inside the unit unless I have to...

    Hopefully, some Yamaha experts can chime in with any other things I should order from Mouser and replace. I've heard something about diodes in the C-2a and replacing them with two of the ones EW talks about tied in series (can't remember the part number at the moment but i have a few of them on hand).

    Looking for recommendations for things to consider replacing on the M-80/C-80 and C-2a. Thanks everyone!
     

     

    Please register to disable this ad.

  2. jdsalinger

    jdsalinger AK Subscriber Subscriber

    Messages:
    877
    Location:
    KCMO
    PM your email address and I'll share my C2a cap list from Mouser.
     
  3. OMGCat!

    OMGCat! AK Subscriber Subscriber

    Messages:
    2,997
    Location:
    El Sereno, CA
    It seems that replacing a whole lot of parts is called for in the C2a. There's a thread that's been active for a while where people go through them. From what they say it's well worth the effort.
    The C-80 is not built to the same standards but it's no slouch once restored.
     
  4. mr.muddles

    mr.muddles Active Member

    Messages:
    451
    Location:
    Portland, OR
    The only thing I've found is the links to the japanese repair blogs on the vintage knob. I've tried searching the C-2a threads on here maybe I missed one... Mostly just people opining about which Yamaha preamp is the best :)
     
  5. stoutblock

    stoutblock If it sounds good, it is good... Subscriber

    Messages:
    9,535
    Location:
    Northwest USA
    Last edited: Aug 25, 2018
  6. mr.muddles

    mr.muddles Active Member

    Messages:
    451
    Location:
    Portland, OR
    I just got done reading through this entire thread! Chocked full of good info... hopefully mine does not have the resistor issue, but I may change them all anyway.

    I made an offer on both the m-2 and the c-2a but it was declined. Since I had just only recently gotten the M-80 I was not trying to get another M series amp this soon unless it was for a real steal. The other thing that needs to be stated is the original owner had engraved their license number in very large print on the front face plate of the M-2. I don't find the M-2 particularly attractive to begin with, and this in combination with the marred face plate made it easy to walk away from. The guy wasn't willing to let it go easy because he said he had just paid $400 to get it working again. I'm planning on getting the 2 preamps up to snuff and enjoy the M-80 for awhile and then probably think about searching out a PC2002M since I think its a better looking M-2. I have a pair of NS-1000 and have heard from Avionic and Flipper I think? That the PC2002M is what drives them best.
     

     

    Please register to disable this ad.

  7. mr.muddles

    mr.muddles Active Member

    Messages:
    451
    Location:
    Portland, OR
    Doing a listening test on the C-80 with SACD input through AUX using the headphone out and it's sounding pretty nice...haven't completely finished the recap and noticing some improvement already. Transistors TR 150 and 149 (the heat shielded ones) are very hot to the touch... I know this isn't new information but any suggestions for keeping these cooler that don't include drilling holes in the top cover? Would attaching some more metal to the heatsinks for more dissipation be helpful?
     
  8. OMGCat!

    OMGCat! AK Subscriber Subscriber

    Messages:
    2,997
    Location:
    El Sereno, CA
    I like my M-2 but with an M-80 I would be plenty happy too.
    Unless it's something super rare you're better off waiting. Yamaha made a LOT of these and another will pop up eventually if you decide you want an M-2.
    I ended up paying like 1/3 of ebay prices for a nearly perfect M-2 from the original owner in the box just a few months ago. I missed out on the matching C-2a but I've already got one with less than perfect cosmetics to hold me over until I find a replacement.

    It sounds like for best performance a re-resistoring is called for but if you spot check some resistors while you're in there and they consistently test ok, get it in good working shape and decide if you want to go forward with that later. If they're all over the place with drift and/or showing open then you might not have a choice.
     
  9. avionic

    avionic " Black Knights " Subscriber

    Messages:
    42,091
    Location:
    Fort Dodge, Iowa
    Those pass transistors are supposed to run hot, Hence the heatsinks..
     
  10. avionic

    avionic " Black Knights " Subscriber

    Messages:
    42,091
    Location:
    Fort Dodge, Iowa
    I have never said that. Not even in a drunken stupor.Must have been the porpoise.Which I strongly disagree with..
     
  11. mr.muddles

    mr.muddles Active Member

    Messages:
    451
    Location:
    Portland, OR
    Hah, sorry to put words in your mouth I must have confused someone else's comment with your own.. I've scoured too many AK threads...
     

     

    Please register to disable this ad.

  12. mr.muddles

    mr.muddles Active Member

    Messages:
    451
    Location:
    Portland, OR
    What's the best approach to cleaning the switches on the C-80 my tone bypass is a little scratchy.. i just finished with the volume loudness board but I'm not really sure the best way to get deoxit into these little alps switches...
     
  13. avionic

    avionic " Black Knights " Subscriber

    Messages:
    42,091
    Location:
    Fort Dodge, Iowa
    Disassembly.
     
    m3gunner likes this.
  14. stoutblock

    stoutblock If it sounds good, it is good... Subscriber

    Messages:
    9,535
    Location:
    Northwest USA
    The C-80/C-85 are sleeper preamps IMHO. The M-80 will do you well.
     
  15. mr.muddles

    mr.muddles Active Member

    Messages:
    451
    Location:
    Portland, OR
    once the switch is pulled from the board is disassembly obvious? I've never taken apart one of these and don't want to brute force pry it apart and break it
     
  16. mr.muddles

    mr.muddles Active Member

    Messages:
    451
    Location:
    Portland, OR
    You do have some NS-1000M if my memory is correct, though? What do you like over PC2002M.. I've never tried the Kenwood mono blocks from the Lab series
     

     

    Please register to disable this ad.

  17. avionic

    avionic " Black Knights " Subscriber

    Messages:
    42,091
    Location:
    Fort Dodge, Iowa
    I have NS-1000, NS-1000M and NS-960's
    upload_2018-8-26_13-48-11.png
     
  18. avionic

    avionic " Black Knights " Subscriber

    Messages:
    42,091
    Location:
    Fort Dodge, Iowa
  19. avionic

    avionic " Black Knights " Subscriber

    Messages:
    42,091
    Location:
    Fort Dodge, Iowa
    MOSFET goodness

    upload_2018-8-26_14-18-16.png
     
    Last edited: Aug 26, 2018
    milo63 and vishalk like this.
  20. mr.muddles

    mr.muddles Active Member

    Messages:
    451
    Location:
    Portland, OR
    Haha, nice collection! Maybe one day I will stumble upon some of those
     

Share This Page