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eguitarClint 7th January 2013 11:46 PM

Fender Champion 110 Problem
 
Hi,

I'm new to this site and was hoping to get some help.

I have a Fender Champion 110 and it would not become silent when the volume was turned all the way down. At first I thought this had to do with a bad connection to ground (later I found out I just needed to clean the pot). Anyways, I went in and noticed that somebody had already moved around the jacks. The joints looked kinda bad and I wasn't getting any continuity on the traces by the external speaker and output jacks. I was able to add some solder to the joints to gain continuity. Now the amp has a loud squeal. Kind of as if it were oscillation.

I tried reversing what I did. There was a hum from the amp and not the speaker. No sound from the speaker at all.

I checked the 1n4003 diodes and they were okay.

There's no solder jumping across the traces either.

If anyone can offer help that'd be great. Any pictures of the traces by the jacks would be helpful too.

Thanks!

kevinkr 8th January 2013 12:02 AM

:cop: Since this is an instrument amplifier I have moved it to the appropriate forum.

Tesla88 24th January 2013 09:00 AM

Check all connections , is a solid state design , schematic attached.

I will remove for test R55 - 47k , now output stage is isolated from the rest , still squealing? if Yes , is something about power section , maybe the Ic or feedback and zobel network.
If Not squealing , try injecting signal at C33 , or simply touch the negative terminal of C33 , if you hear HUMMMM is ok :)


http://music-electronics-forum.com/a...pion-110-c.gif

eguitarClint 24th January 2013 01:19 PM

Thanks for the reply. And the schematic! I couldn't find it anywhere.

As I was looking over the circuit board I noticed that their was a bit of solder connecting one of the capacitors to both ends of a resistor near the input. I must have spilled a little but when I cleaned it up it worked fine. The volume just doesn't turn down all the way so I was thinking I'd try replacing the pot.

I do have a question though. How exactly do I inject signal into C33 or "touch" it?

Thanks again!

Tesla88 24th January 2013 03:15 PM

If now amp work well (no more squeal and you can ear the guitar at output) , and the only issue now is about volume pot , just change the pot with a new one with same value...

Quote:

How exactly do I inject signal into C33 or "touch" it?
You don't need this anymore , if amp works! Anyway , removing R55 isolates the ouput stage , so if you touch with a finger the negative lead C33 , is like you're putting a signal that your body receive and you must hear a sort of Hum at mains frequency. Or if you have a signal generator , an mp3 reader can work , you simply connect this as a source with common at GND of amp and signal to C33 ...

Enzo 24th January 2013 07:41 PM

Glad you got back to where you started.

As to the volume not going to zero. Is this really a problem? Or do you just object to it on some sort of principle? I mean, how often do you desire to play at zero volume?

The amp has a gain and a volume for the drive channel, and a volume for the normal channel. All three of those could be called volume control. SO which control has the issue? Two of the controls are in the feedback loops for op amps, and do not go to ground like a conventionakl voltage divider. Only the drive channel volume does that. SO those two to me would not be surprising if they left a litttle sound at minimum seting.

eguitarClint 25th January 2013 06:56 PM

Thanks for the information Tesla88! I'll replace that pot.

For Enzo:

I'm talking about the volume for the normal channel. Even when it is turned down to zero it is still REALLY loud. Almost like it's on 8 which is too loud for my jazz band and practice room. I ordered a new pot of the same value and when it comes in I'll try it out. Fortunately the drive and gain channel volume you mentioned work fine.

Enzo 25th January 2013 09:25 PM

Sorry, I misunderstood. When you said it didn't go silent, I assumed you meant it came close but not all the way. You are saying instead that it stays way up. The opposite of my assumption.

Bad pot sounds reasonable, pull the pot from the circuit and test it with a meter to be sure.

eguitarClint 26th January 2013 06:29 PM

No problem. I'll trying testing the pot out of the board. Thanks.

eguitarClint 12th February 2013 12:34 AM

I checked the pot out of the board and it was fine. I even replaced the pot and I still have the same problem. With the volume at zero the guitar is still audible and then as I turn it up to 1 or 2 the volume jumps to loud.


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