HELP ME SAVE 74 SUPERLEAD!!

[heckitar66]

Neikeel, what pot are you speaking of? I checked the solder joints and they seem good. The v2 cathode resistor still reads 99.9k.

Doug H, I haven't tried different tubes since I replaced the two 100's I found that were bad

I have a question about the 10k's between pin 6 of v2 and the filter caps they're attached to. On the schematics I've seen, one red wire goes to the positive terminal of the preamp filter cap, the other red wire goes to the phase inverter filter cap. Both of mine go to the preamp cap. Also I thought there should be a connection between the v1 plate resistors and the preamp filter cap but I don't see how that is achieved in this amp.

[heckitar66]

I'll else the tube next but how do I check the socket if it's not the tube?

[heckitar66]

Guys, you've done it again. IT'S FIXED!!! The tube was bad and I think the socket might need to be replaced. I replaced v2 with another tube and instantly readings were much closer to normal. Pin 8 gave me erratic readings so I bent it in a little and it seems to be good for now.

Just ran downstairs and fired it up and it sounds fantastic!!

[neikeel]

Guys, you've done it again. IT'S FIXED!!! The tube was bad and I think the socket might need to be replaced. I replaced v2 with another tube and instantly readings were much closer to normal. Pin 8 gave me erratic readings so I bent it in a little and it seems to be good for now.

Just ran downstairs and fired it up and it sounds fantastic!!

[heckitar66]

I'm a little embarrassed that the last step was as simple as replacing a tube. I hope none of you feel that your time was wasted. I replaced all the tubes as soon as I got the amp back from the techs and all the preamp tubes were new. I had tried many different tubes including an at7 in the PI and since the amp still seemed to have the same sonic defects I didn't think it was tube related.

My son looked for a long time to find this amp. He was thrilled when he found it. When we picked it up it was in a homemade head box and I had a feeling it was going to need some work. It looks like some really bad things happened to it.

Anyway, thank you all especially Neikeel and Doug H. Getting this amp sounding right meant a lot to me. I still have to replace the presence cap but all readings seem close enough and it sounds like I knew it could.

Thanks again!

[bigsmitty]

Glad to hear you got it fixed

[heckitar66]

Thanks bigsmitty!

[Doug H]

awesome news, debugging threads are always a learning experience that pay back in dividends.