Dumble amp OD channel sound cut off problem when fading

[psychepool]

I made a # 183 based 35W Dumble ODS and use it well.

Recently, there was a sound cut-off like noise gate.


The clean channel works fine and there is also no problem using the drive pedal.
The problem is in OD channel.
First, when I switch the channel to the OD for the first time with the standby switch on, no sound is heard for more than one second on the OD channel.
After 1 second or longer, the sound begins. Once the sound is begin, the sound will not be muted when switching the channel.

However, even after the channel switching works normally, the OD channel is distorted and cut off when the sound is faded out as though the noise gate is overworked.
Basically it's okay, but when the sound starts to get smaller, it happens.
Sometimes, when I turn on my power and continue to use it, it's okay, but sometimes it's not.

I'm using it at home so master volume is always low setting. (9 O'clock or 12 O'clock with attenauater)
Of course, there was no problem when I first completed the amplifier.
I made it and use about 2~3 years.

What is the cause? Is it caused by careless production such as cold soldering?
Or could there be a problem with the relay?

Please let me know if there are any possible causes of the above mentioned problems.

[fred.violleau]

I made a # 183 based 35W Dumble ODS and use it well.

Recently, there was a sound cut-off like noise gate.


The clean channel works fine and there is also no problem using the drive pedal.
The problem is in OD channel.
First, when I switch the channel to the OD for the first time with the standby switch on, no sound is heard for more than one second on the OD channel.
After 1 second or longer, the sound begins. Once the sound is begin, the sound will not be muted when switching the channel.

However, even after the channel switching works normally, the OD channel is distorted and cut off when the sound is faded out as though the noise gate is overworked.
Basically it's okay, but when the sound starts to get smaller, it happens.
Sometimes, when I turn on my power and continue to use it, it's okay, but sometimes it's not.

Have you tried to switch preamp tubes? looks like it could be a failing tube.

My humble 2 cents.

Fred.

[pompeiisneaks]

I doubt it's a relay, they either work, or don't, it's still just a switch. (I guess a failure mode could make them more like a resistor if they build up carbon on the contacts? but seems unlikely) Cold solder joints are a possibility, but all that takes is either visual inspection for any that aren't nice and shiny and a smoothly covered surface and/or chopsticking the amp while on to see if any of the joints make noise.

I like the idea of Fred's to try swapping out the tube first, though as that's more likely an 'over time' problem that's much more common.

~Phil

[Stevem]

I don't know that I would fully rule out the relay!
I would jump it out in favor of the OD channel and see if it still acts up!
In fact you could jump out stages as a way to narrow it down to a problem stage.