Accuphase c-200 preamp selector switch

[quadmatrix82]

Hi there accuphase gurus I have a accuphase c-200 preamp sounds superb it's been recapped and many transistors and resistors replaced as needed however when I switch from aux to phono there's a nasty crack that comes from the speakers usual cleaning of switches hasn't fixed it -

any ideas where I can look to track this issue down? I have a spare pre c200 and swapped out the boards but the problem is still there any help or suggestions would be appreciated!

 

[slimecity]

I think this is common with this gear, my C200 thumps, crackles and pops all over the place, especially the volume control. Perhaps the controls just need an extra amount of cleaning?

 

[quadmatrix82]

I think this is common with this gear, my C200 thumps, crackles and pops all over the place, especially the volume control. Perhaps the controls just need an extra amount of cleaning?

I wish it was cleaning the switch has been cleaned a lot with deoxit and a q-tip when I hear the crack the speaker pulsates almost like it has dc on it I'm wondering where else to look other than the eq boards??

 

[quadmatrix82]

Just an update I found a few resistors on the eq boards looking low to spec even out of circuit awaiting a mouser order before I can see if this is causing the issue

 

[quadmatrix82]

Yep it's a very clean unit it's intermiddent issue as you do it more the cracking becomes less worse the first few times are the worse and you can see the woofers move a lot when it happens and it's only when phono gets selected

 

[bktheking]

Mine doesn't do that so it must be a faulty component.

 

[Yggdrasill]

I turn down the volume first on mine and nothing gets through to the speakers.

 

[quadmatrix82]

Update! Problem fixed found two resistors way out of spec all good now!

 

[quadmatrix82]

R28 and r31 3.9m ohm
R29 and r32 4.7m ohm
R6 and r7 330k ohm

All were way out of spec out of circuit

All the resistors that had some light burn marks were also changed even if they tested good as a precaution