Flakey PM-4000 mute groups

W

W. Mark Hellinger

Sophomore
May 16, 2011
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My PM-4K has a glitch with the mute groups... tripping on in random fashon for no apparent reason, but not locking in when so prompted. Does anybody have any ideas where I should start looking to fix this?
 
Re: Flakey PM-4000 mute groups

Tim Perry said:
The old repair techs adage is: first fix the power supply, then check for other problems.
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Sage advice Tim.

I checked the power supplies right off... they appear to be delivering correct and stable power. Also, the board is powered via primary and back-up power supplies through a Yam SU4000 switcher.

I suspect the problem is in the TB module (which contains the mute group masters)... I vaguely recall trouble-shooting and fixing this same (or very similar) problem in a PM-1800 and a couple of PM-3000's... but it's been years ago... and I didn't keep notes... and my brain got filled up with other stuff since then.
 
Re: Flakey PM-4000 mute groups

Had a PM-4kM with similar problem. Mute groups 1,2,7, and 8 would not always stay muted and would 'chatter' on and off.

Replaced just the master mute switches and the problem was solved. The master mute switches (all 8) come as one part with one Yamaha part number. We kind of panicked when we first saw the price, thinking we had to buy 8 parts!

Hope this helps.
 
Re: Flakey PM-4000 mute groups

Travis Porter said:
Had a PM-4kM with similar problem. Mute groups 1,2,7, and 8 would not always stay muted and would 'chatter' on and off.

Replaced just the master mute switches and the problem was solved. The master mute switches (all 8) come as one part with one Yamaha part number. We kind of panicked when we first saw the price, thinking we had to buy 8 parts!

Hope this helps.
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Yes, that helps a bunch. The symptoms you describe are just what I'm experiencing.

Thanks. I'll report back after I do the fix.
 
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