This amp belonged to a co-worker's dad who is now deceased. Unfortunately, the son doesn't have the electronic knowledge his dad had. He told me about this amp, & that it doesn't power up. I suggested checking the fuse, & he replaced it, but it blew after 3 seconds. I suggested that he bring it to work, & I would take a look at it. When he brought it, it had no power tubes in it. I pointed that out, & said I would take it home to look at it. I put good 6L6's in it, replaced the fuse, & it also blew within 3 seconds. I took the chassis out, & everything looks to be original except the filter caps & one of the power supply diodes. Looks like a germanium? It looks clean, especially considering its age & the damp climate here in Louisiana. I can't tell if the transformers have been changed, but both are also very clean with no rust. None of the caps are blistered. When powering it up, I hear a slight hum, a bit higher pitched than 60hz, then it blows the fuse. So, I don't know what else to try other than suggesting that he take it to a local amp tech.