Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Fresh_Start on September 09, 2021, 08:05:46 pm

Title: Amp Turns Itself Off Then On Again
Post by: Fresh_Start on September 09, 2021, 08:05:46 pm

The first amp I built is a Tweed Fender Princeton - 5F2-A circuit except a choke in the power supply like a 5E2.  Originally built almost 15 years ago, but I’ve re-built it at least once. Haven’t been inside it for years.


Today I was messing around with a new pedal for maybe 15 minutes when the amp went silent and the pilot light went dark. Before I got over to the amp, it came back on and I played for a good 30 minutes more. 5 or 6 ours later, I started it up again and the same thing happened. No magic smoke - sounded fine before and after auto-shutdown.


Obviously something is wrong so what should I look for?


Oh!  I’ve been using the surge suppressor side of an old UPS for amps and pedals. Pedals stayed lit when the amp went dark.


Thanks in advance for any clues…


Chip

Title: Re: Amp Turns Itself Off Then On Again
Post by: thetragichero on September 09, 2021, 08:14:16 pm

intermittent switch? maybe dust from sitting around (my airless paint sprayer lives on my front porch. after about a year of not using it it wouldn't turn on. fuses were good but when i checked the power switch some mud wasps had made a nest near it. some contact cleaner WITH THE UNIT UNPLUGGED fixed that right up)

Title: Re: Amp Turns Itself Off Then On Again
Post by: Latole on September 10, 2021, 06:40:25 am

Bypass Power switch.

Test amp and report.