1. Time for some upgrades in server hardware and software to enhance security and take AK to the next level. Please contribute what you can to sales@audiokarma.org at PayPal.com - Thanks from the AK Team
    Dismiss Notice

Yamaha CX-1 Thread

Discussion in 'Yamaha' started by Bratwurst7s, Sep 30, 2017.

  1. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

    Messages:
    4,211
    Location:
    Munich, Germany
    The old caps in the Tone Control section:
    C539: 330µF/16v = 291µF, 0.29 ohms, 2.1%. Replaced with KL in 25v.
    C544: 330µF/16v = 299µF, 0.32 ohms, 2.2%.
    C547: 10µF/25v = 10.97µF, 1.3 ohms, 1.4%. Replaced with FC 50v.
    C548: 10µF/25v = 9.98µF, 2.1 ohms, 2.4%.
    C523: 1µF/50v = 0.937µF, 3.3 ohms, 0.9%. Replaced with MKS2 63v.
    C530: 1µF/50v = 0.962µF, 3.5 ohms, 1.0%.
    C526: 0.22µF/50v = 0.21µF, 8.8 ohms, 0.7%. Replaced with MKS2 63v.
    C527: 0.22µF/50v = 0.22µF, 9.8 ohms, 0.8%.

    The old caps in the Phones Drive:
    C533: 47µF/16v = 46.25µF, 1.4 ohms, 2.3%. Replaced with FC 50v.
    C534: 47µF/16v = 45.95µF, 1.4 ohms, 2.2%.
    C531: 10µF/25v = 10.06µF, 1.2 ohms, 1.2%. Replaced with MKS2 50v.
    C536: 10µF/25v = 10.23µF, 1.3 ohms, 1.6%. Replaced with MKS2 50v.
    C550: 1µF/50v = 0.982µF, 3.0 ohms, 0.6%,
    C552: 1µF/50v = 0.965µF, 3.1 ohms, 0.7%.
    C553: 1µF/50v BP = 1.02µF, 6.4 ohms, 1.4%.
    C556: 0.1µF/50v = 0.107µF, ?, 0.9%.

    My cap checker refused to show ESR on that last cap for some reason.

    Cheers,
    James
     
    Last edited: Feb 11, 2018

     

    Please register to disable this ad.

  2. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

    Messages:
    4,211
    Location:
    Munich, Germany
    Some of the buss bar connections are pretty grey, looking like some cold solder joints. I used a large chisel tip on my iron and some flux and got them all shiny and new looking. The entire board has been reflowed and de-fluxed now and re-installed. I put a thin film of light synthetic grease on the volume, input selector and rec-out shafts before re-installing their bushings. The first 2 photos are before, the 3rd after.

    DSC04737.jpg DSC04739.jpg DSC04744.jpg

    Next up are the 2 small phono amp boards.

    Cheers,
    James

    edit: After reflowing the boards I used a magnifiying glass to inspect them for solder bridges or stray solder globs. I blew the left channel of a perfectly good A-520 last year because of such a mistake. I'd like that to be the only time that I made that mistake.
     
    Last edited: Jan 11, 2018
  3. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

    Messages:
    4,211
    Location:
    Munich, Germany
    Concerning the scans of the layouts and schematics. They turned out great. And huge, the schematics at least.

    My friend did a great job of stiching together the 4x scans per side of the schematic. There a few small glitches where a trace makes a slight jog but in all very clear and usable. But the finished jpg's are 52mb and 48mb. Too large to send as an email attachment. So at this point I'm going to look around and see if I can find a local printshop that can scan them in one shot and give me something small enough so send as an attachment.

    The board layouts also turned out great and turned out much smaller. I only have to convert the tiff files to jpg and I can zip them up unto an easily attachable file.

    So it may take a little while but I am dedicated to providing my fellow AK members with useful scans of the schematics and layouts.

    Cheers,
    James
     
    Last edited: Jan 10, 2018
  4. rottalpha

    rottalpha Yamaholic

    Messages:
    1,810
    Location:
    Middle of Crook County
  5. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

    Messages:
    4,211
    Location:
    Munich, Germany
    I've heard of those but I haven't found anywhere over here to buy them.

    Have you used them? If so I have a question(s) about the pin-outs. 2SK389 has 7 pins. LSK389 has 8 (smd) or 6 (to-71). How did you deal with that? Adapter? Does Brown-Dog make an adapter for them?

    Your B-1 is sure looking beautiful. Nice work.

    Thanks,
    James
     
    Beau Geste likes this.
  6. rottalpha

    rottalpha Yamaholic

    Messages:
    1,810
    Location:
    Middle of Crook County
    they are not pin for pin direct replacement, but if I were in need to replace one, I would not consider that an impediment. Let's hope you do not need to change yours.
     
    Bratwurst7s likes this.

     

    Please register to disable this ad.

  7. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

    Messages:
    4,211
    Location:
    Munich, Germany
    Agree Strongly!!!

    James
     
  8. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

    Messages:
    4,211
    Location:
    Munich, Germany
    I had to kick myself today because I realized that I had wanted to bypass the signal path elcos with a 0.1µF film cap and forgot to do that on the Tone and volume boards. So out they came and got the caps added. I only did the 4x 47µF KL's because the 330µF KL's are already bypassed with those little green poly film caps on the backside, they can be seen in the pics in post #142.

    DSC04745.jpg DSC04747.jpg DSC04748.jpg

    Cheers,
    James
     
    Beau Geste likes this.
  9. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

    Messages:
    4,211
    Location:
    Munich, Germany
    Next the 2 small phono boards were removed and worked. The old caps on sub-board Main-2 measured:
    C185: 10µF/25v = 10.00µF, 2.0 ohms, 2.2%.
    C188: 10µF/25v = 9.96µF, 2.1 ohms, 2.4%.
    C168: 10µF/25v = 10.23µF, 2.1 ohms, 2.6%.
    C179: 10µF/25v = 10.23µF, 2.1 ohms, 2.7%.

    C185 & 188 were replaced with FC in 50v. For C168 & 179 there was just enough room to install some MKS2 film caps.
    After that the boards were reflowed and cleaned.

    DSC04749.jpg DSC04750.jpg DSC04751.jpg DSC04752.jpg

    Cheers,
    James
     
    Beau Geste likes this.
  10. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

    Messages:
    4,211
    Location:
    Munich, Germany
    The sub-power-supply standby board has just enough slack in the wires to be tipped out and tilted over to work it.
    There are only 3 caps here, one of which is on the trace side.

    Old caps:
    C565: 470µF/16v: 393µF, 0.33 ohms, 3.2% vLoss. Replaced with a FC 470µF/35v.
    C571: 47µF/16v: 46.17µF, 1.7 ohms, 4.4%. Replaced with FC 47µF/50v. This is the one mounted on the bottom.
    C561: 0.1µF/50v: 0.108µF, (no result), 1.1%. Replaced with MKS2, 63v.

    DSC04754.jpg DSC04755.jpg DSC04756.jpg

    Cheers,
    James
     
    Last edited: Jan 12, 2018
    Beau Geste likes this.
  11. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

    Messages:
    4,211
    Location:
    Munich, Germany
    DSC04759.jpg DSC04761.jpg DSC04763.jpg

    Oh yeah, I replaced the standby relay also. I was lucky that I had one because afaik those Omron's are no longer in production.

    Cheers,
    James
     

     

    Please register to disable this ad.

  12. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

    Messages:
    4,211
    Location:
    Munich, Germany
    I found out with my AX-750 that the easiest and actually only practical way to remove the main board is to remove the rear panel first. After that it's pretty easy to get the board out. I de-soldered the 3 pin power connector and the whole board was free. The panel only has to be pulled back a bit to make enough room to remove the pcb.

    Oh, and I went over to the post office today and picked up the Mundorf 6800µF caps. Everything is finally here.

    I only have 2 more photos for today, the rest have to wait until tomorrow.

    OK. This was the easy stuff up to now. The main job will get started tomorrow.

    DSC04766.jpg DSC04767.jpg

    Cheers,
    James
     
    Beau Geste likes this.
  13. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

    Messages:
    4,211
    Location:
    Munich, Germany
    I'm nearly finished with re-capping the main pcb. I'm going to wait until it's finished (tomorrow) and do a photo tour then.

    For the PSU and protection sections old caps measurements...
    C221: 4700µF/35v = 3902µF, 0.04 ohms, 2.5%. Replaced with Mundorf 6800µF/63v.
    C222: 4700µF/35v = 3786µF, 0.05 ohms, 2.3%.
    C214: 100µF/35v = 86.94µF, 0.67 ohms, 3.9%. Replaced with FM 50v.
    C216: 100µF/35v = 92.38µF, 0.51 ohms, 1.8%.
    C212: 33µF/25v = 34.95µF, 0.75 ohms, 2.0%. Replaced with KL 35v. This cap has a 100pF poly cap installed in parallel.
    C203: 22µF/16v = 21.74µF, 2.2 ohms, 3.4%. Replaced with FM 50v.
    C215: 22µF/25v = 21.7µF, 1.5 ohms, 2.0%.
    C198: 10µF/25v = 9.98µF, 3.0 ohms, 4.8%. Replaced with FC 50v.
    C202:10µF/25v = 9.46µF, 2.7 ohms, 4.3%.
    C204: 10µF/25v = 10.68µF, 1.2 ohms, 1.3%.
    C205: 10µF/25v = 10.53µF, 1.3 ohms, 1.4%.
    C213: 2.2µF/50v = 2.3µF, 2.3 ohms, 1.2%. Replaced with MKS2 63v.

    And at this point I found the answer to my early question about C206 and C211 in the 0-DB Amp section. Simply a mistake on my part. I miss-identified C206 and was actually looking at C215. C206 & 211 are both 2,2µF/50v Muse. So that whole thing was just James being dumb.

    The 0-DB Amp:
    C208: 2200µF/25v = 1612µF, 0.04 ohms, 3.0%. Replaced with FC 2700µF/35v.
    C209: 2200µF/25v = 1619µF, 0.04 ohms, 3.0%.
    C227: 47µF/25v = 46.01µF, 0.76 ohms, 2.7%. Replaced with KL 35v.
    C228: 47µF/25v = 45.91µF, 0.76 ohms, 2.7%.
    C206: 2.2µF/50v = 2.28µF, 2.1 ohms, 0.6%. Replaced with MKS2 63v.
    C211: 2.2µF/50v = 2.17µF, 2.1 ohms, 0.7%.

    And the Phono section.

    C189: 2200µF/25v = 2197µF, 0.06 ohms, 2.6%. Replaced with FC 2700µF/35v.
    C190: 2200µF/25v = 2197µF, 0.06 ohms, 2.6%.
    C137: 1000µF/6.3v = 864.1µF, 0.16 ohms, 2.5%. Replaced with FC 10v.
    C138: 1000µF/6.3v = 858.3µF, 0.16 ohms, 2.8%.
    C139: 1000µF/6.3v = 846.9µF, 0.16 ohms, 2.8%.
    C140: 1000µF/6.3v = 956.1µF, 0.15 ohms, 2.5%.
    C161: 1000µF/6.3v = 846.9µF, 0.17 ohms, 2.8%.
    C162: 1000µF/6.3v = 861.9µF, 0.17 ohms, 2.8&.
    C144: 470µF/25v = 461.6µF, 0.07 ohms, 1.6%. Replaced with FM 50v.
    C148: 470µF/25v = 448.1µF, 0.08 ohms, 1.6%.
    C149: 470µF/25v = 443.7µF, 0.08 ohms, 1.9%.
    C150: 470µF/25v = 448.5µF, 0.07 ohms, 1.6%.
    C131: 100µF/10v = 86.73µF, 1.3 ohms, 4.1%. Replaced with KL 35v.
    C136: 100µF/10v = 87.43µF, 1.3 ohms, 3.7%.
    C143: 10µF/25v = 10.08µF, 2.2 ohms, 2.5%. Replaced with MKS2 50v.
    C145: 10µF/25v = 10.13µF, 2.2 ohms, 2.8%.
    C146: 10µF/25v = 9.97µF, 2.2 ohms, 3.0%.
    C152: 10µF/25v = 10.09µF, 2.3 ohms, 2.9%.

    So, only the CD buffer and input sections to go, that's just 24 caps. And then a few hours doing the reflow and cleanup. With a little luck I'll be listening to this thing by tomorrow evening.

    Cheers,
    James
     
    Karl vd Berg likes this.
  14. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

    Messages:
    4,211
    Location:
    Munich, Germany
    OK. I just have time for a quick note. It's time for Saturday home theatre and Wife is almost ready.

    I worked on this unit for a good 6 hours today. Changed all of the caps in the CD buffer and input sections, reflowed all connections cleaned the board and did an inspection. Good that I used a magnifying glass because I found 1 solder bridge from the reflowing. Corrected.

    Closed her up and puckered up my cheeks and turned her on for the first time and NO SMOKE. That's always good.

    The short answer is that I just listened to Rory Gallagher's first solo album and, this thing is a monster. A hammer. Freaking great!

    I don't mean to be a tease but Wife is ready and it's time to go. The full report comes tomorrow.

    Cheers,
    James
     
    tmsears, OMGCat! and 808_state like this.
  15. Karl vd Berg

    Karl vd Berg Super Member

    Messages:
    1,967
    Don't forget to leave it "on" for a few days "burning-in", haha!:beerchug:

    Glad to know this massive work turned out REALLY WELL!! Very good the checking of caps, specially the bigger ones, C221, etc... :thumbsup:
     
  16. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

    Messages:
    4,211
    Location:
    Munich, Germany
    Heh, heh, I think that my burn-in method will be to play music through it for a few hours every day. ;)

    OK. Down to business.

    The last of the old caps.
    C141: 22µF/25v = 23.04µF, 0.90 ohms, 1.1% vLoss. Replaced with FM 50v.
    C142: 22µF/25v = 22.67µF, 0.92 ohms, 1.1%.
    C154: 10µF/25v = 10.32µF, 1.8 ohms, 1.7%. Replaced with MKS2 50v.
    C157: 10µF/25v = 10.02µF, 1.8 ohms, 1.6%.
    C103: 10µF/25v = 10.22µF, 2.0 ohms, 2.5%.
    C106: 10µF/25v = 10.07µF, 2.1 ohms, 2.6%.
    C109: 10µF/25v = 10.18µF, 2.0 ohms, 2.6%.
    C112: 10µF/25v = 10.19µF, 2.1 ohms, 2.6%.
    C113: 10µF/25v = 10.15µF, 2.2 ohms, 2.7%.
    C116: 10µF/25v = 10.06µF, 2.8 ohms, 2.8%.
    C119: 10µF/25v = 10.04µF, 2.1 ohms, 2.7%.
    C122: 10µF/25v = 10.24µF, 2.1 ohms, 2.8%.
    C125: 10µF/25v = 10.11µF, 2.1 ohms, 2.6%.
    C128: 10µF/25v = 10.30µF, 2.1 ohms, 2.4%.
    C247: 1µF/50v = 0.952µF, 3.2 ohms, 0.9%.
    C248: 1µF/50v = 0.961µF, 3.3 ohms, 1.0%.
    C258: 1µF/50v = 0.975µF, 3.5 ohms, 1.1%.
    C259: 1µF/50v = 0.965µF, 3.3 ohms, 1.0%.
    C151: 1µF/50v = 0.965µF, 4.4 ohms, 1.7%.
    C152: 1µF/50v = 0.951µF, 4.4 ohms, 1.6%.
    C153: 1µF/50v = 0.933µF, 6.5 ohms, 3.0%.
    C154: 1µF/50v = 0.962µF, 4.0 ohms, 1.5%.

    That last cap, C154 is the 2nd cap that I found that the silk screen is backwards to the way the cap was OEM installed. The board layout drawing shows the minus the way the cap was installed.

    So all of this listing the old cap values was probably completely boring to anyone but Karl and I but I found it interesting to see how the old caps had held up. And most of them had held up well. The Elna Duorex were all pretty good. The Elna brown and Nichicon Muse were a crapshoot, mostly good but some sizes had dropped as much as 20%. The Nichicon 1µF BP all had pretty high ESR. It looks like C153 was on it's way towards failing.

    This is the first time that I ever thought of using the rather obvious tactic of using the cap date codes to pin the age of an amp. The newest cap was produced in week 18 of 1993. And we can see that Yamaha had no problem using 2 year old caps because a fair number of the Nichicons were from early '91. Most of the Elna's were made in '92, a few in '93.

    As I was working on this board I freaked out when I noticed a scratched through trace off of one end of R222 in the Phono section. I thought at first that I had somehow done it and was ready to hit myself. But I realized that it was in fact a deliberate cut in the trace about 1mm wide. After checking the board layout one can see that the trace is not supposed to be joined at that spot. So this was a mistake in the etching photo-tool that was corrected by scratching the trace. There is a second small cut trace up near R232 or so (I didn't pin that one down exactly).

    This stuff leads me to think that my pre-amp is a very early production model. I did professional production etching for 12 years (photo-chemical machining). The normal way to correct such a photo-tool error is to scratch out (or touch up) the feature on the photo-tool ink as a temp measure and then make a corrected one for mass production. This mistake wasn't caught until after a fair number of boards had been produced. Add to that how many caps and resistors have been tacked onto the trace side of the board, as well as a number of by-pass film caps added in parallel to an elco by opening up the through-holes and shoving them through together.

    It would be interesting for 808_state and devnull etc to post some pics and cap date codes if you ever do a recap.

    So, to do a final re-cap of the re-capping, I counted 98 elcos in this pre-amp. I was able to replace 43 of them with Wima MKS2 film caps. That's something over 40% I think and that makes me happy. There were another 4 or so 10µF that I would have liked to swap with film but there was just no way that they would fit because of space. And when you see the photos one can see that I barely got a lot of the 10µF Wima's in there.

    I made a number of pragmatic choices for the new caps based on how the new ones measured. Some of my early choices got set aside because I didn't like the way that they measured. And ALL of the 470µF that I bought measured low. FC and FM in 25v and 35v, KL in 25v and 35v, KZ in 25v and 50v. I don't know what it is about that value but the highest new cap measured around 460µF and lowest around 440µF, average about 450µF.

    Oh, btw, the 2x Mundorf's measured 6612µF and 6656µF. So, well on the low side of nominal but still way above the old Nichicons.

    OK. enough babble. Photos in the next post...

    Cheers,
    James
     
    Last edited: Jan 16, 2018
    Karl vd Berg likes this.

     

    Please register to disable this ad.

  17. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

    Messages:
    4,211
    Location:
    Munich, Germany
    2 pics of C254 and also the hand cut traces...

    DSC04774.jpg DSC04775.jpg DSC04777.jpg DSC04779.jpg

    Cheers,
    James
     
  18. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

    Messages:
    4,211
    Location:
    Munich, Germany
    Some overview shots of the finished main pcb...

    DSC04776.jpg DSC04780.jpg DSC04781.jpg DSC04786.jpg DSC04787.jpg

    Cheers,
    James
     
    tmsears and Beau Geste like this.
  19. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

    Messages:
    4,211
    Location:
    Munich, Germany
    The power supply and 0-DB sections...

    DSC04789.jpg
    DSC04790.jpg DSC04791.jpg DSC04792.jpg DSC04793.jpg

    Note that I didn't get all of the old glue completely removed. Even lots of acetone wasn't getting it off and I was doing more damage to the silk screen than good with scratching and so decided to apply the "good enough in this instance" rule.

    Cheers,
    James
     
    Karl vd Berg and Beau Geste like this.
  20. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

    Messages:
    4,211
    Location:
    Munich, Germany
    The Sys-Control and Phono sections...

    DSC04794.jpg DSC04795.jpg DSC04796.jpg DSC04797.jpg

    Cheers,
    James
     
    zaibatsu and Beau Geste like this.

Share This Page