CR-800 turn-off transient

[Blue Shadow]

Thanks to all the resources (Merrylander and others) a friends CR-800 seems to be working nicely except for a turn off transient after the relay clicks.

Wonder what needs to be looked at?

The SM from here and the posts by Merrylander have gotten the balance and idle current set to specs, the switches are clean. What is next?

[Dark Knight]

Are you talking about a slight "chirp" from the speakers when you turn off the CR-800?

DK

[zenith2134]

Check the DC at the speaker terminals. My sx-1050 did that as received, but went away after zeroing the DC offset.

[Blue Shadow]

Yes it is a chirp, but I need to hear it again tomorrow to verify that is what I would call it.

I did the DC offset check and it was low until the unit was turned off. Below 5mV in each channel. Turn off brought a peak of 85mV or so, depending on when the meter read the number. This was after the relay clicked.

The manual says to redo the center bias and the idle current a few times to get really good numbers and I'll do that again, just to be sure.

Thanks for the comments so far.

[inductor]

if it was after the relay opened then there is something wrong with the relay the speakers should be disconnected then

[EchoWars]

Could be a 4PDT with a contact or two fused.

[Blue Shadow]

I'll keep listening to the situation, because as of today the unit is powering down quietly. It may have been the long dormant period of unknown duration and the recent continued use that has helped.

This unit, missing a channel, dirty and needing some TLC got a nice dose of Deoxit especially in the vertically-oriented pre-power separation switch on the back panel near the heat sinks which cause the dust to flow. This brought the channel back and work got the knobs and faceplate clean. All it needs right now are a few of the 12V 60mA bulbs for the meters.

http://e28-535i.com/upload/CR-800-4.jpg

http://e28-535i.com/upload/CR-800-1.jpg

http://e28-535i.com/upload/CR-800-3.jpg

[gary202007]

Hello everyone,

I'm hoping you will be able to help me. I have a similar issue with my CR-800 which used to be my Dads. Sadly he passed away in 2005 and so I love this amp as much for sentimental reasons as I do for it totally amazing sound. I really can't tell you how impressed I have been with it and it gives me lots of listening pleasure everyday, it even makes my iPod sound amazing!

Anyway this amp has made the speakers 'pop' when you turn it off for years, as long as I can remember. I just live with it or push down the mute switch before the power switch which seems to pretty much silence it. Is this 'pop' going to damage my speakers?

Sadly this isn't its only issue. My main concern is that lately when the unit is switched on from cold the left channel is quite degraded. Its significantly quieter than the right channel and is distorted. Turning the unit off and on a couple of times seems to fix this issue but I'm worried its going to get worse.

I really want to keep this amp going and can see you guys are real experts. What can I do to try and sort it out. I've tried all the switches and they don't help. I think it could be something like a dirty/sticky relay which I can hear clicking in just after the power is turned on. Am I on the right track and if so what can I do?

Thank you very much indeed for your help.

Kind regards,

Gary Eary.

[Blue Shadow]

If you haven't cleaned the switches you can do that and see if it helps. The one that kept one channel from making it to the speakers was on the back and can be accessed inside back between the two round black capacitors in the pic above.
Here is how to do it:
http://audiokarma.org/forums/showpost.php?p=1888690&postcount=10

Take care of this and see if it helps.