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Old 26th Sep 2018, 11:59 am   #11
cmjones01
Nonode
 
Join Date: Oct 2008
Location: Warsaw, Poland and Cambridge, UK
Posts: 2,669
Default Re: 120W PP EL34 amplifier re-born.

Quote:
Originally Posted by Diabolical Artificer View Post
2) Hot swop ECC82 into LTP base, IE with HT etc applied, whilst monitoring 6.3v rail = 6.3v crashes to 1.2v, LM317 heatsink getting V hot, but not too hot to touch. Result both IP and OP of ECC83 attenuated. Is the ECC82/LTP acting like a diode?
Are the ECC83 and ECC82 heaters both powered from the LM317? If so, the extra current drawn by the ECC82's heater when it's cold may well be sending the LM317 into foldback current limiting, hence the output crashing to 1.2V and staying there.

Chris
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