Hey Flames, here's one for ya!
Posted: Wed May 19, 2004 12:50 am
I just got a '65 Twin Reissue in the shop for repairs today.
Customer reported that he'd turn it on, play through it for about 10 minutes, then smell something burning. A removal of the chassis and visual inspection didn't reveal anything out of the ordinary(no blown screen resistors, etc).
Plug it in, fire it up on standby, and do a voltage check on pin 5 of all the output tubes. V7 & V8 OK. V9 & V10...OUCH!!! 0 volts on the grids!!!
Well, a quick trace and found one of the 220K bias feed resistors blown open with no visual indication. Checked the screen resistors and found no bad ones. So the burning smell would have to be...yep, you guessed it, the OT!
Ohmed out the OT and everything seemed OK. So I removed it and took the end bells off. Smelled it, didn't really smell burnt, but my sense of smell sucks. A quick look at the blue primary wire revealed scorch marks on it and the paper looked discolored toward the top of the core.
So now I get to call the customer and tell him that it's gonna cost around $200 in parts to fix it.
Jon
Customer reported that he'd turn it on, play through it for about 10 minutes, then smell something burning. A removal of the chassis and visual inspection didn't reveal anything out of the ordinary(no blown screen resistors, etc).
Plug it in, fire it up on standby, and do a voltage check on pin 5 of all the output tubes. V7 & V8 OK. V9 & V10...OUCH!!! 0 volts on the grids!!!
Well, a quick trace and found one of the 220K bias feed resistors blown open with no visual indication. Checked the screen resistors and found no bad ones. So the burning smell would have to be...yep, you guessed it, the OT!
Ohmed out the OT and everything seemed OK. So I removed it and took the end bells off. Smelled it, didn't really smell burnt, but my sense of smell sucks. A quick look at the blue primary wire revealed scorch marks on it and the paper looked discolored toward the top of the core.
So now I get to call the customer and tell him that it's gonna cost around $200 in parts to fix it.
Jon