I just bought a SJ-502A and trying to troubleshoot. The schematics I found don't exactly match up 100% and want to make sure the voltages are correct before shoving $500 + in tubes into it seeing how it is 20 years old or so. So at the moment B+ is 530v, -B is at -72v, +B1 is at 502v and +B2 is at 500v (after climbing up for a few seconds). No idea if this is within spec and calling Black Ice Audio the guy on the phone wants nothing to do with me. I have 2 different schematics (one of which is in the all over the internet) and the other more closely resembles mine. But I'm going with the scheme online here and the differences are R14 and R15 are 12k, C7 and C12 caps were omitted I was told in my model, R23 and R24 are 62k/3w, and C6 is a 100u/460v with a polypropylene .22 cap on it as well (which I removed because it was odd). Ebay listed it as working and contacted the seller and got a partial refund because the tubes it came with wouldn't bias and overall tested with odd readings. The listing did state the tubes will need to be replaced. So like I said I want to make sure the voltages are within spec but I can't get a schematic that resembles mine and god only knows who else messed with this amp. I did have to replace the C5 on the end there and didn't seem to make a huge difference but instead on the 500v i was getting more like 490ish before replacement. If someone can get back to me of something I can check, or perhaps replace all of the caps and buy resistors that match the scheme. Want to know what you guys are seeing. I'm uploading the schematics I have and a schematic that I edited a few things on to make it look like my set up. Let me know what you recommend. Also I like fixing stuff but this one I'm scratching my head on.
Thanks in advance.
Thanks in advance.
