CD100C amp volume going nuts

frenchy2010

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Hi,
I have a CD100C and a F
My C today started to have the volume go up and down like a mad man. at some point the volume controle on the back was not working anymore.
I switched the AMP between the 2 units and the problem moved with the AMP

Is this just a bad AMP thaty needs to be replaced ?

I played with the AVC switch to turn it of and the volume went even higher so I turn it back on.
The problem seems to go away when I turn off the whole unit for a while to cool down and comes back when warm, ...

Any ideas/suggestions ?
 
Rowe jukebox amplifiers are well known for numerous cold solder joints on both driver boards and on the preamp board. Pay attention to the soldering at the connectors on those boards as that's where the problems occur.

Also, the electrolytic capacitors on those boards are reaching the age where they may also be going bad just like on a video monitor.

However, I feel your problem is the cold solder joints. On the preamp board the 13 pin jumper plug soldering and where the driver boards plug into the preamp board are particularly troublesome.
 
Thanks

I am getting the solder iron out :)

You are probably right on a bad solder joint.

I took it appart and back on to see if there was an obvious burned bomponent and now the volume control does not work at all

I'll post what I find out tomorrow when I find the problem if I find it
 
Make sure you have that 13 pin jumper plug inserted in the correct orientation on the preamp board. It's easy to plug it back in backwards. The preamp schematic shows which pins are jumpered.

The volume control plug going into the amplifier is another one that can be plugged in backwards by mistake.

Also, on the preamp board is a single orange wire that plugs in. If you forgot to plug that in, there'll be no sound. That is the mute signal wire to unmute the sound.
 
I have sound just no volume control

I checked the jumpers they are good.
the volume control connector is also where it needs to be and how it needs to be.
The mute4 switch is in

I need to take the board appart and check the volume controle for bad connections.
There is not much to volume controle it's a variable resistor and a simple circuit, ....
 
That didn't work

I redid all the connector soldering but that didn't do it.

I am more thinking that one of the little amps in the Auto volume control fried (U5) maybe

not sure how to test these
 
Recap the preamp and driver boards. There are several electrolytics on the preamp board located next to the hot voltage regulators. The heat gets to those capacitors.
 
I am not sure how to recap the driver boards

or the pre-amp.
how do I do that?

I am pretty sure it's a problem with the AVC (Auto Volume Control) because when the volume works the sound goes up and down by itself and when the volume is not working then it has a steady sound volume, just stuck on high
 
I was looking at A&B

they have a pre-amp board for sale....

Do you know of a place that would be able to repair my board if I ship it to them for a smaller fee than the board itself ?
 
Also

I did unplub the whole amp from the plug to make sure it would cool down and that doesn't help anymore. it used to at first, ... I think or might have been unrelated
 
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