Laney TT50H No Output

[ca7922303]

Has low somewhat distorted output thru send jack only. Replaced all power/preamp tubes w/known good tubes. Contact cleaner on cables in efx loop in and out/overnight, jumped efx loop: No change. Have schematic, multimeter, some exp. desoldering, soldering caps/resistors, etc. No how to drain voltage off before working on an amp. Any ideas would be greatly appreciated.

 

[ehdwuld]

Re: Laney TT50H No Output

Effects loop was my Laney's kryptonite

But you've done that

Can you plug into the effects return and get any sound

This divides the amps preamp and power amp
If no sound from fx return then its probably the output section is bad

 

[ca7922303]

Re: Laney TT50H No Output

Just ran line out and record out to another amps input and got a good clean signal. None of the preamp controls on channels 1,2,3 work, but volume 1 and volume 2 work, amp mute works, and fx mix is scratchy and tries to cut volume off at "0" but intermittent scratchy signal still comes thru at "0". Also, there is a high pitched whistle if volume is turned up past "8" on either amp. 2nd amp does not do this when TT50H is not plugged into it. Previously jumped efx loop with no change in output.

 

[ca7922303]

Re: Laney TT50H No Output

Just ran line out and record out to another amps input and got a good clean signal. None of the preamp controls on channels 1,2,3 work, but volume 1 and volume 2 work, amp mute works, and fx mix is scratchy and tries to cut volume off at "0" but intermittent scratchy signal still comes thru at "0". Also, there is a high pitched whistle if volume is turned up past "8" on either amp. 2nd amp does not do this when TT50H is not plugged into it. Previously jumped efx loop with no change in output.

Wondering if a bad efx mix pot could cause the preamp on this head to not function?

 

[ehdwuld]

Re: Laney TT50H No Output

Shoot yeah