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Topics - pontiacpete

When this amp came to me I plugged it in and it made sound but soon started to smoke and then an electrolytic cap blew, C21 10uf/50v.You cannot view this attachment.

Also the LM3886 chip was smoking and had burn marks under the legs. I replaced both the cap and the LM3886. The amp is making sound but it is distorted. So far I check all the transistors under the heat sink for any shorts in circuit. All of them seem to be ok. I pulled Q6 which was reading a dead short between B-E but out of circuit it measures to be good. Q6 is a MPSA06 but on the schematic I have from GK says it's an 2SC3478. Confusing to me. THe trim pot R9 is not changing the distorted sound. Any ideas where I should go from here? Thanks!
Amplifier Discussion / help w/ peavey TNT 150
January 14, 2011, 06:38:53 AM
This amp has a scratchy post pot. I replaced the pot and swapped out all the electrolytics in the area and the nearest ICs, checked resistors and changed the one .1uf cap closer to the input. At the moment I don't have a schematic, but I hope to have it by tomorrow morning. There is negative voltage on the pot as it is increased up to about -.9vdc. On a light limiter the light jumps up brighter as the pot is turned.

Does anyone have any advice?
Thanks in advance.