gk 400-rb combo issue

mrniceguy715 · #1 09-24-2011, 07:50 PM

When the amp is powered on and you adjust the master the only output is a scratchy distorted sound. Sometimes you can make out a bass is being played but mainly sounds like static. I removed the head and cleaned all the pots. Everything "looks" good no loose connections anywhere. Any suggestions on where to start more troubleshooting?

**B-string** · #2 09-25-2011, 12:12 AM

Effects return jack. It may be corroded, try a patch cable from effects send to effects return. If it works properly with the patch cable (like an instrument cord), the effects return jack needs cleaning. There are contacts inside the jack that connect preamp to power amp.

mrniceguy715 · #3 09-25-2011, 07:56 PM

That did help some. Now I can hear the note I played but get static and a sound like the speakers are blown. I know they are not because for a few minutes it played nice and clear and I turned it off thinking it was fixed.... then back to the buzz.

**B-string** · #4 09-25-2011, 09:17 PM

Did you clean the jack with Contact Cleaner (like DeoxIT NOT WD-40)? If you used a proper contact cleaner and it was a ok for a while, give it another shot of cleaner and work a plug in and out several times. NO WD-40 !!

mrniceguy715 · #5 09-25-2011, 10:16 PM

I used an electric parts cleaner, what I uses to clean cellphone boards and such. I will try the brand you recommended.

**B-string** · #6 09-25-2011, 10:59 PM

Rid-Ox also works well but leaves more residue to mop up

mrniceguy715 · #7 09-30-2011, 01:50 PM

I noticed that it plays with no distortion if the contour knob is set past 3/4