DSL trouble.

[LiveeviL2000]

Tonight I was playing my DSL40CR and the sound suddenly went low. Then it began to crackle. But only on the clean/green channel. At one point the sound cut out completely then returned but lower volume.
The 3 other voicings sound fine.

Tube issue? I hope.

 

[froman5150]

You didn't happen to notice if your tubes were glowing an usual bright red when that happened did you?

 

[iblive]

Ha

Tonight I was playing my DSL40CR and the sound suddenly went low. Then it began to crackle. But only on the clean/green channel. At one point the sound cut out completely then returned but lower volume.
The 3 other voicings sound fine.

Tube issue? I hope.

Had an issue on my 1974 Traynor YGM3 years ago. Playing away and lost about 1/2 volume. Don’t know on your amp, but in my case it was a tube. Amp was old so I just did a retube and issue resolved.

 

[Amp Mad Scientist]

Tonight I was playing my DSL40CR and the sound suddenly went low. Then it began to crackle. But only on the clean/green channel. At one point the sound cut out completely then returned but lower volume.
The 3 other voicings sound fine.

Tube issue? I hope.

Intermittent problems are the hardest to find but it's a watching and waiting game...
One strategy is to change the preamp tubes and wait to see if that stops the problem.
That's the first thing you would usually do.

In the DSL 40CR is a microprocessor chip that has been known to go bad.
The processor controls the channel switching and signal routing etc.

If the preamp tubes don't stop the problem you can start to suspect the processor chip.
However the processor chip is factory programmed and the service center will be the one to change it.
It's not an off the shelf part.

 

[Amp Mad Scientist]

You didn't happen to notice if your tubes were glowing an usual bright red when that happened did you?

From the description it would not be the power tubes.
If it only happens on one channel, it's going to be a preamp tube (if it is a bad tube at all).

 

[froman5150]

My 2000 acted similar when what I later found out was the board became conductive then proceed to let out the proverbial smoke was why I was curious .

 

[LiveeviL2000]

You didn't happen to notice if your tubes were glowing an usual bright red when that happened did you?

I did not notice

I will fire it up tomorrow and take a look.

 

[Amp Mad Scientist]

My 2000 acted similar when what I later found out was the board became conductive then proceed to let out the proverbial smoke was why I was curious .

The DSL 50 and DSL 100 have that problem, but not the DSL 40 CR.

 

[LiveeviL2000]

From the description it would not be the power tubes.
If it only happens on one channel, it's going to be a preamp tube (if it is a bad tube at all).

Yes. It’s only on the one channel and only the one voicing.

I will check it out tomorrow. See if it does it again.

 

[Inspector #20]

I did not notice

I will fire it up tomorrow and take a look.

Change out V1

 

[Amp Mad Scientist]

Yes. It’s only on the one channel and only the one voicing.

I will check it out tomorrow. See if it does it again.

Do you have any 12AX7 tubes?
change them and then let it ride for a while.
See if the problem stops.

 

[LiveeviL2000]

Would it be best to swap them all out?

 

[Inspector #20]

Would it be best to swap them all out?

For starters, I suggest only V1.

 

[mcblink]

He just got a couple joyo bantamps, so he's got at least 2 12ax7 around. He can use a known good one to roll through and try to identify any potentially bad one for starters, yes?

 

[Inspector #20]

He just got a couple joyo bantamps, so he's got at least 2 12ax7 around. He can use a known good one to roll through and try to identify any potentially bad one for starters, yes?

Yes.

 

[LiveeviL2000]

He just got a couple joyo bantamps, so he's got at least 2 12ax7 around. He can use a known good one to roll through and try to identify any potentially bad one for starters, yes?

I have 2 tubes here already, I'll check it out in the morning.

 

[Inspector #20]

I have 2 tubes here already, I'll check it out in the morning.

V1 is your "green" channel. It's the first tube on your left looking in the back of the DSL40C.

 

[SkyMonkey]

V1 is your "green" channel.

V1 is part of the signal chain in both the Classic and Ultra channels.
Both V1 triodes are used by the Ultras (and Classic Crunch, I think).
Only one V1 triode is used by the Classic Clean.
That is why an ECC823 (x17 & x100 triodes) can lower the gain of the Ultras and not the Classic Clean.
The x17 triode is only used by the Ultras (+ the x100), the Clean only gets one x100 (as it does with an ECC83).

It is tedious, but use one ECC83 that you know to be good, and swap it out with the preamp tubes one at a time, starting with V1.
After each swap test the amp.
This way you identify the bad tube (if there is one) and avoid chucking any good ones.

 

[Iron1]

Sounds like a good excuse to buy some upgraded tubes to me. Hopefully it's not what @Amp Mad Scientist said regarding the microprocessor. But, if it is and you have to take it in, at least you have a collection of Joyo's to jam thru in the meantime. Hope it's an easy fix.

 

[Amp Mad Scientist]

I have 2 tubes here already, I'll check it out in the morning.

In guitar amps
V1 is the closest tube to the input jack.
V1 is the tube that goes bad more often...but it could be any of them.

These amps also have mechanical relays.
Sometimes the relay wears out, it could cause crackles.

Sometimes it's caused by bad solder connections.

But the preamp tubes is usually what you would try first.
If that fails to fix it then you start looking at other stuff.