Gallien Krueger Fusion 550 problem with noise

[gelfin]

I have a Fusion 550. It has been perfectly fine for years and hasn't come out of the studio for around 3 years. A couple of weeks ago I switched on and when unmuted there was a "fuzzy noise". Not very loud but intrusive. I have checked all connections, inputs outputs etc and no change. The noise does get louder when turning up the master volume. The high mid control does seem to have a small effect. All other switches and dials have no effect. I have changed the valves and the noise is just the same. Any clues or pointers would be appreciated.

[gjones]

3 minutes ago, gelfin said:

I have a Fusion 550. It has been perfectly fine for years and hasn't come out of the studio for around 3 years. A couple of weeks ago I switched on and when unmuted there was a "fuzzy noise". Not very loud but intrusive. I have checked all connections, inputs outputs etc and no change. The noise does get louder when turning up the master volume. The high mid control does seem to have a small effect. All other switches and dials have no effect. I have changed the valves and the noise is just the same. Any clues or pointers would be appreciated.

 

I experienced something similar.

 

I bought a used GK MB 800, from Basschat, and when I first tested it at home I could hear a slight distortion in the sound coming out of the speakers.

I took the casing off and made sure all the connectors on the mainboard were seated properly, then put it back together. When I set it up and tested it again, the distortion had gone.

 

I've gigged with it many times since then and haven't had any problems.

 

I recommend you do the same, it could sort the issue.

[Downunderwonder]

10 minutes ago, gelfin said:

high mid control does seem to have a small effect

If we assume you could be wrong about that you should try inserting a lead into the fx send return loop. This will remove the possiblity it is the switch contact in the loop jack playing up.