Centaur A1224 Acoustic PA issue

[cgdanz68]

Hello Folks. I'm trying to fix my solid state guitar amp/PA. The issue is that sound fades in and out after it warms up a bit and not at regular intervals. The power light by the power switch is on when this occurs. I have dug around in there and there seemed to be an issue with the reverb wiring and I re-soldered what I thought was the problem ( because it seemed to work ok after that ) However the problem still exists. The amp/pa has two channels, channel 1 has an xlr jack and a 1/4" (I tried only plugging the mic into channel one and the guitar into channel 2, didn't seem to matter) and two 1/4" jacks, one active and one passive on channel 2. It also has a low filter switch that either is set on cut or boost, and this seems to be on the 2nd channel. Sometimes when I change the switch setting on the filter it seems to bring the sound back. coincidence? Any help would be appreciated. Also, I am a licensed electrician so I have some electrical theory floating around in the ol' brain. Thanks

[joecool85]

I would first start by opening up the amp, turning it on then poking at everything with a plastic Bic pen or similar (Juan likes to suggest using chopsticks).  Odds are you will find that something in there has a loose connection and is causing your volume to fade when warm due to thermal expansion.

[cgdanz68]

Ok, I will give that a shot, and I have chopsticks so I will start with them. I will let you know how it goes. Thanks

[cgdanz68]

So, I opened her up and while a mic was on, took the chopstick and pushed some of the wires around. One of the wires of the reverb unit had a lousy connection, so I re-soldered that and made them a little longer, because it was kind of short. I also found a bad solder joint in the lo filter circuit that went from the switch to the board. Re-soldered that and everything seems to be working fine. Thanks for the tip, obviously it helped. Great site, lots of good stuff. I will continue to read them and hopefully (or not?) be active on the site myself. Thanks again .

Chris

[joecool85]

So, I opened her up and while a mic was on, took the chopstick and pushed some of the wires around. One of the wires of the reverb unit had a lousy connection, so I re-soldered that and made them a little longer, because it was kind of short. I also found a bad solder joint in the lo filter circuit that went from the switch to the board. Re-soldered that and everything seems to be working fine. Thanks for the tip, obviously it helped. Great site, lots of good stuff. I will continue to read them and hopefully (or not?) be active on the site myself. Thanks again .

Chris

Glad you got it fixed.  If you have any other issues or if you just want to "talk shop", please come back  :tu: