This quite old (I'm fairly sure that it is early 70's) Traynor YRM-1 Reverb Master, 50 watt amp was brought in by a local gentleman (Kevin) who explained that it was not running/sounding right and that it had a loud hum too! It didn't take much sorting out after checking it on the test gear. The scope clearly showed a dreadful 100cls hum coming over the top of the signal.
After removal from the case for investigation (note the novel idea of the whole top removal, this makes life much easier for a service engineer!), it simply turned out that the twin electrolytic on the front-end pre-amp part of the HT supply had spat it's guts out! Yet ironically enough the main HT caps were fine. This is rather unusual as it would normally have been the other way around.
Replacement of the said capacitors, a re-bias, and spraying of all the potentiometers (whilst it was open anyway) brought everything back to spec and...... to producing a nice sound too!
Cheers, John.
