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Old 21st Jun 2022, 5:26 pm   #14
mikes08
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Join Date: Dec 2021
Location: Canterbury, Kent, UK.
Posts: 133
Default Re: Quad 303 pop on switch on

Quote:
Originally Posted by Radio Wrangler View Post
I was wondering whether the PSU regulator did that, as a soft start, but then both channels would suffer, and the PSU seems not to have any timing components.

On the power amp board, C100 and C104 look to be involved in controlling the turn-on process. C100 looks like an input DC block, but it's really the DC block for the shunt element of the second part of the feedback divider. C104 does that job in the first part.

This is a shunt-feedback amplifier and so the output Z of the preamp is involved, though the 2-section divider limits the extent. It's good for reducing the effect of non-linearity in the input stage, but less good from the viewpoint of sensitivity to pteamp Z and also carries a small noise disadvantage.

David
C100 and C104 have just been replaced on both boards as part of the Dada upgrade kit. I guess i could swap them across boards and see if the fault follows. I have ordered some transistors so will swap those first and see where that leaves me.
Thanks
Mike

Last edited by mikes08; 21st Jun 2022 at 5:49 pm.
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