No output from amp!! Help!!!!

[mrgraypant]

Hello all, I have an Ashdown Mag 300 bass amp here and it's had some problems. My friend just bought it and at first he turned it on and the front light came on but only a faint hum from the speaker, after making sure all jacks were in the right place and volumes were up, we took it out of the cab and had a look to see if we could find any obvious problems like a bad solder joint or loose wire, but no such luck. We put it back into it's cab and it just worked! Although there was a soft of ocean wave noise coming from the amp every so often. After some troubleshooting we cleaned off the input jacks and it was miles better but still apparent. I said "Leave it here with me overnight ill give it a good clean" so I take the amp back out and I took off the front PCB, cleaned all the input jacks well and put it back together, to my horror I was back to that faint hum and no signal. I have plugged another amp into the speaker with the same 1/4 inch jack and it works fine, then I hooked up an amp to the Effects Send jack, and there is clear signal from there, but still nothing from the speaker output. I need help!

[The Dude]

So, you tried the effects send to another amp. Did you try inserting signal into the effects return? The return jack should be a switching jack. Try cleaning it and running a plug in and out a few times. Also, try jumpering effects send to return to see if that solves the problem.

[mrgraypant]

So, you tried the effects send to another amp. Did you try inserting signal into the effects return? The return jack should be a switching jack. Try cleaning it and running a plug in and out a few times. Also, try jumpering effects send to return to see if that solves the problem.

Nothing when jumped effects send to return, and nothing when applying signal to effects return. Although I should add when you turn the amp off there is a sort or warbling like you'd find on an operational amp. Thanks for the reply

[mikeydee77]

Warbling might be sub harmonics effect if engaged.

Very common that the jacks need replacing when they get older. Sounds like you have an unreliable joint considering intermittent symptoms.

Do you know about using a chopstick to diagnose bad joints and do it safely?

[mikeydee77]

Oh... mute button as well

[glebert]

Did your friend buy it at a place he can return it?