Quality professional services
Replaced 6VAC heater power to a 5VDC power for first tube in preamp section
Installed 100 Ohm 2w potentiometer with wiper to ground in transformer heater output
Copper tape installed in cabinet (bottom & sides)
Blowing fuses during power up due to intermittent tube rectifier GX34 and the output tubes (EL84) being unbalanced.
Also, looking at the thermal image, it can be seen that one of the tubes is running cooler that the others
Original problem point to a faulty transistor in the output stage but also found high leakage current in diodes
Recently we serviced a Guyaton amplifier having an overheated output power tube 6L6GC and after extensive troubleshooting we found the problem was in the bias section of the power tube.
The tube was running at approximately 300% of the recommended plate dissipation due to faulty decoupling capacitors. Later on, we realized that all the high voltage electrolytic capacitors had problems causing not just the damage of the power tube, but additionally tremolo malfunction and noisy signal
Have you ever wondered what the frequency response of your guitar amp is?
I had the opportunity to fix a HiFi amp (Behringer-Ultratone K450) and recorded the response to a flat input between 20Hz to 20KHz. Later on, I compared it with a Fender Hot Rod Deluxe and here are the differences:
American manufactured Hot Rod Deluxe received with high level of noise.
After a complete service all high voltage capacitors were replaced with brand new F&T capacitors improving noise level (see attached photos).
After 36 years it was time to change all electrolytic capacitors.
Broken capacitor
Broken high voltage tag
Broken reverb connector
Original report for this Fender was only overheated bias resistor, but after a complete inspection we found so many things to improve an correct in the amp.
Vintage Amp Repair
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