I am done, and am listening to the M-500 right now - sounds sweet, but it's not on my AL-IIIs, just some bookshelf M&Ks. Anyway, I learned quite a bit. First off, the traces on the M-500 are very delicate. In removing a part, I actually removed the trace with it (it was at the end of a trace run). I thus had to scrape off some of the trace coating further down and solder to it. It wasn't difficult, but not something I'd ever done before. I don't know if the traces on other Carver gear is this delicate (this unit is made in Japan), but it certainly isn't like the Heathkit AR-1500 I built in 1970.
Second, I found that all the capacitors listed in the Service Manual were not needed. Actually, the M-500t was closer to what was needed than the M-500 manual (I must have had a later model). So, You should pop the lid before you order parts and check to see. Actually, it probably would have saved me less than a buck not ordering the extra parts.
Finally, I found that all the traces to make this into a M-500t were there, plus some. There was a couple of traced holes for an indicator light (if I'd had an appropriate LED, I probably would have put it on the board, just for grins). There was tracing for a switched outlet, the front power switch, an impedance switch - neat stuff.
OK, here's some picks that I haven't posted earlier.
Amp board before:
Amp board after:
Notice all the blue caps are gone. Sorry about reversing my camera angle.
And finally, just now in operation:
Below is the list of capacitors that I bought to do this project:
Carver Corp. # Qty Description Panasonic # Digi-Key # Spacing M-500 Capacitor Cost Total Comment
MS-16TW471M 2 470ÂµF 16v EEU-FC1C471L P10247-ND 3.5 C103-C104 $0.47 $0.94
MS100TW1R0M 8 1ÂµF 100v EEU-FC2A1R0 P10765-ND 2 C119-C122, C135-C138 $0.24 $1.33 Buy 10
MS-50TW1R0M 3 1ÂµF 50v EEU-FC1H1R0 P10312-ND 2 C123-C124, C517 $0.27 $0.81
MS-25TW1R0M 1 1ÂµF 25v (50v) EEU-FC1H1R0 P10312-ND 2 C522 $0.27 $0.27 Substituted 50v
MS-16TW470M 3 47ÂµF 16v EEU-FC1C470 P11196-ND 2 C133, C605-C606 $0.34 $1.02
MS-16TW101M 2 100ÂµF 16v EEU-FC1C101 P11198-ND 2.5 C134, C526 $0.34 $0.68
NP-25TW470M 1 47ÂµF 25v ECE-A1EN470U P1179-ND 2.5 C201 $0.31 $0.31
MS-16TW221M 1 220ÂµF 16v EEU-FC1C221 P11199-ND 2.5 C202 $0.48 $0.48
MS-50TW470M 1 47ÂµF 50v EEU-FC1H470 P10321-ND 2.5 C203 $0.28 $0.28
MS-25TW101M 1 100ÂµF 25v EEU-FC1E101S P10269-ND 2.5 C525 $0.23 $0.23
MS-16TW100M 3 10ÂµF 16v ECE-A1CKG100 P910-ND 2 C527, C603-C604 $0.19 $0.57
MS-25TW4R7M 1 4.7ÂµF 25v (35v) ECE-A1VKG4R7 P920-ND 2 C528 $0.19 $0.19 Substituted 35v
BC80682YC60GH4 2 6800ÂµF 80v ECE-T1KA682EA P10642-ND 22.5 C508-C509 $9.05 $18.10
BC50682XB50CC3 2 6800ÂµF 50v ECO-S1HA682CA P6686-ND 10 C510-C511 $5.20 $10.40
BC80222M250CC2 2 2200ÂµF 80v ECO-SIKA222BA P7505-ND 10 C512-C513 $4.89 $9.78
The caps that I found that weren't used were C603 and C604. You will see that I substituted a 50v cap for a 25v cap for C522. That makes them the same as C123, C134 and C527, so you can order 4 of those. Actually, if you wanted to save a few more cents you could use the extra 2 caps you got when you bought 10 of the 100v 1Âµ caps for C123 and C124, and just order two 50v caps for C522 and C527. I also had to substitute a 35v cap for a 25v one for C528, because the 25v caps were only available in lots of 10.
The high dollar caps are the big ones in the power supply C-508 and C509 have four prongs (two are just for stability on the board) and look like chicken feet. Anyway, I made the substitutions because I wanted to find a single supplier for the project (save minimums and shipping charges). I got the entire project parts from Digi-Key (http://www.digikey.com/
). All the caps are at least 3000 hour life and 105Â°C rated.