DSL40c Dead

[kokanee85$]

Over the weekend I was having some fuzzy ghost notes while playing, like a feint echo.. I was worried maybe the speaker was blown so I swapped it out, and while I had it open I put in some new power tubes been in since 2019. Well I fired up the amp on standby only 1 tube lit, turned power on and other tube lit up and blew. Shut off immediately had some smoke coming out of amp. Put old tubes back in. Both glowed but no sound.

Opened up and inspected things, fuses weren’t blow, but R-111 looks cooked? Any ideas what could be the problem

 

[kokanee85$]

I should also mention I know just enough to get myself into trouble. Reading through the forum I think im gonna look into a better made amplifier. Maybe boutique

 

[paul-e-mann]

I should also mention I know just enough to get myself into trouble. Reading through the forum I think im gonna look into a better made amplifier. Maybe boutique

Just buy something classic, 2204, 2203, 1987, 1959, etc. etc.

 

[kokanee85$]

Just by something classic, 2204, 2203, 1987, 1959, etc. etc.

Assuming these are classic models? I’m looking for a 2 channel amp for studio and small gigs.

 

[paul-e-mann]

Assuming these are classic models? I’m looking for a 2 channel amp for studio and small gigs.

You dont need 2 channels, set a 1 channel amp cleanish and use an OD pedal out front for gain. If you must have 2 channels look at the Jubilee.

 

[KraftyBob]

I have the same amp. R111 is the dropping resistor for the screens. That obviously needs to be replaced, but I would also check R114 & R116 which are the screen resistors.

Did you check the fuses with a multimeter or just visually? Fuses should always be checked with a meter as they can look fine, but might be blown under the end cap which you can't see. FS1 is the HT fuse.

This amp uses Pentode/triode mode to reduce power, which basically ties the screen to the plate, you should put the amp in standby when changing between the two modes. Not sure if that came into play here, but wanted to pass that along just in case.

If you decide to fix it yourself make sure you drain the filter caps before pulling the board to replace R111. There are plenty of videos online on how to do that. Report back.

 

[kokanee85$]

I have the same amp. R111 is the dropping resistor for the screens. That obviously needs to be replaced, but I would also check R114 & R116 which are the screen resistors.

Did you check the fuses with a multimeter or just visually? Fuses should always be checked with a meter as they can look fine, but might be blown under the end cap which you can't see. FS1 is the HT fuse.

This amp uses Pentode/triode mode to reduce power, which basically ties the screen to the plate, you should put the amp in standby when changing between the two modes. Not sure if that came into play here, but wanted to pass that along just in case.

If you decide to fix it yourself make sure you drain the filter caps before pulling the board to replace R111. There are plenty of videos online on how to do that. Report back.

Great info thank you so much! Would that resistor being nasty cut off the output? I didn’t test fuses just visually inspected, I’ll take a look at that tonight. Also with that resistor assuming the board needs to be removed from the chassis to replace it? I would rather have a tech do the work but a few of the tech in my areas are backed up for a few months. Then at 110$ an hr is it worth it to fix in your opinion?

 

[kokanee85$]

You dont need 2 channels, set a 1 channel amp cleanish and use an OD pedal out front for gain. If you must have 2 channels look at the Jubilee

That’s totally up to the player bud, I enjoy playing clean jazz, folk rock, country which in my opinion sound best more clean. Also enjoy playing 80’s to current Rock/Metal, so having a nasty channel and nice clean sounds best to me. They make 2 channels for a reason..

 

[KraftyBob]

Great info thank you so much! Would that resistor being nasty cut off the output? I didn’t test fuses just visually inspected, I’ll take a look at that tonight. Also with that resistor assuming the board needs to be removed from the chassis to replace it? I would rather have a tech do the work but a few of the tech in my areas are backed up for a few months. Then at 110$ an hr is it worth it to fix in your opinion?

If that resistor is broken into two separate pieces then you wouldn't have any voltage going to the screen - which would certainly affect all the tubes since that feeds the plates on the preamp tubes too. In the schematic pic you can see that after the rectifier the first point along the way is the OT Center tap - which feeds the power tube plates. Then it goes through R111 and that feeds the power tube screens. From there HT6 feeds V1, V2 & V3, and then finally it feeds the plates of V4 (Phase Inverter).

From what I can tell from your pic (it's been a while since I've been in my amp) it looks like R111 is on stand offs to lift off the board. If that's the case then yes, you would need to pull the board to replace it. If the resistor leads were coming out of the ends then you could get away with clipping off the old resistor and connecting the new one using the existing leads - making sure to have a good physical connection before soldering. You wouldn't need to pull the board in that case.