Help me trouble shoot my GK amp please! With video samples

Try a jumper for the Effects Loop, then use the regular input. GK's are known for this.

 

sounds like you have dirty pots,
try turning the knobs one at a time as you play, see if the noise changes.
best to clean all the pots anyway

 

I jumped mine ten years ago or so and never looked back. Just grab a short pedalboard cable with right angle connectors, jumper the effects loop and if it works,forget about it.

 

[QUOTE="Dan Arciniega, post: 24107783, member: 352540"
best to clean all the pots anyway[/QUOTE]

Best to leave the pots alone. Way too many amps have been ruined by the indiscriminate application of contact cleaner!

 

It indicates that the Return jack is in need of a cleaning.
Here is a copy of another post I did explaining how this works. With pictures.


For those that do not know this is what the effects return jack looks like. See the nipple between the bottom posts, this is what connects your signal with nothing plugged in. See the signal flow lines.





When a plug goes in the nipple is lifted, breaking that connection and the signal comes from the cable.




When you read on here that an amp is cutting out or the volume is good then suddenly goes and we give advice to check the effects loop to see if it still does it, this is why. If it clears up when inserting a plug then that little nipple had some oxidization on it interrupting the signal. It only takes a small film to interfere so you clean it with a wipe of Deoxit D5 and it's all good. No need to keep in the jumper cables.

Never just spray in the jack as you will get parts that you do not want sprayed and that little nipple is hidden under that post.

A little rant while on jack cleaning, NEVER file or sand to clean the contact points. The coating on them is thin and has a corrosive protected coating on it and when you scratch that off it will rust fast, making your problems come back faster and eventually killing the jack. Also your filings that come off could go somewhere you do not want.
A lite chemical wipe is all you need to clean and protect.

 

Look where the nipple is on @S-Bigbottom post. Putting clean on a plug is not going to clean the nipple. But just exercising it might.

Many times jacks and pots can just be cleaned by exercising them.
Plug, Unplug, Plug, Unplug, ...


BTW I don't know what GK it is, but if it has a tube, try re-seating it.

 

The guys on the music-electronics forum love chasing weird amplifier issues and are pretty good helping people who don't really know how to troubleshoot things.

 

The nipple is a below where the plug will reach and may require some rubbing to get it cleaned, a bit more than just the plug in and out thing.

Try both ends of the cable in the loop first Effect Send and Return, if that clears it up go for the cleaning, if not it is tech time contact GK.

 

You may not need to. Turn the amp off, then just slide a jack in and out of both the send and return jack a few times. That will probably do it.

Also, in the future, try to wrap your cable around the cabinet handle or run it underneath the amp from behind so that the the full weight of the cable isn't just being held up by the jack. You will forestall a lot of future problems this way.

 

Glad you got it solved. GK MBFusion into what looks like a fearless 112. Great combo!

 

I’ve been using GKs for decades and never had this problem or any as a matter of fact...

 

My biggest problem (if you could call it that) with my MBFusion 800 into my 12/6, is very low volume jams where I have my master barely cracked open. Less than 1. These little amps are powerhouses. I think I need a MB200 for my low volume stuff...…...