silverface deluxe reverb

[Breausonic]

Hey guys I've got a silver face deluxe reverb I'm working on.After it warms up on the vibrato channel only,the bass drops out of the signal. reverb still there just sounds tinny,all the fullness goes away.wont do it on the normal.happens after 20 minutes and the standby is reengaged.The amp has been recapped sockets cleaned. any thoughts on this

[pdf64]

Does the setting of the trem intensity control affect the issue?
Do all the controls work as normal when it's in the fault mode?

[Breausonic]

deluxe reverb

Does the setting of the trem intensity control affect the issue?
Do all the controls work as normal when it's in the fault mode?

Thats a good question,the reason i say this is its never been engaged no footswitch when this has occurred controls seem to work normally.Ill fire this thing up and double check and get back Thanks!

[pdf64]

Some types of failure of the optocoupler (or oscillator/buffer tube) can mess up the sound of the fx channel whether the trem is switched on or not.

[Mick Bailey]

Make sure the treble pot isn't disconnecting on the bass side when warm. This will leave you with only the treble control of the tone stack connected and only have a limited operation, as you just have effectively a 250pf cap + 250k pot in series with the signal and no low-end. If this is happening then the bass control won't work at all.

[Breausonic]

deluxe reverb

Make sure the treble pot isn't disconnecting on the bass side when warm. This will leave you with only the treble control of the tone stack connected and only have a limited operation, as you just have effectively a 250pf cap + 250k pot in series with the signal and no low-end. If this is happening then the bass control won't work at all.

Will check both of these after work tonight and report back.

[Familyortiz]

I'm not sure about the schematic but if the trem channel is tubed, I'd try a simple substitution with a known good tube. Also, a simple and thorough visual inspection goes a long way. Cheers.

[1ampman]

Check the ground wires going to the brass panel under the controls. Push on them with screwdriver. Also a bad coupling cap would cause bass drop out..... Good luck

[Mick Bailey]

Good point. A bad coupling cap can result in the signal being coupled just through board capacitance and secondary paths. If it's happening when the amp warms up a blast of freeze spray should identify the problem.

[Familyortiz]

Vibrato section tube? Was it checked with a known good tube?