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Old 25th Feb 2018, 1:53 pm   #5
MikeViking
Triode
 
Join Date: Feb 2018
Location: Brisbane, Queensland, Australia
Posts: 17
Default Re: AVO CT160 - relay activates at power on

Well the meter may be busted.

The relay wouldn’t let go. Took it apart and didn’t find anything. Moved it manually a few times to ensure it was moving. Started it up again, this time in the variac, and all good.

We now have 240vac, a glowing red power lamp and 2 good fuses, protection relay is not activating and, oh, no meter movement. The meter should move in the ‘set’ position for calibration/confirmation that the input voltage is ok, but it doesn’t move.

It could be the rectifier diodes. The 2x GEC D77s glow, but I haven’t checked they are producing the expected dc voltages. The paralleled meter and R9 shunt read 9kohm so they are not open circuit. I am hoping that it simply a matter of retubing the rectifiers or replacing with one of the silicon rectifiers in this thread:

https://www.vintage-radio.net/forum/...ad.php?t=74490
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