Marshall DSL40 combo keeps cutting off

Martymig

Martymig

Member
I bought a used Marshall DSL40 and after a few days of use it starts cutting off. I still here the amp humming but the guitar just cuts off.
What's could be causing this ?
 
Rocker68 said:
Re-read your post. You said it still hums. Probably something simple. Cold solder joints maybe.
Click to expand...
What are cold solder joints ? Also, I changed the toggle switch in my expensive guitar but know nothing about soldering. Any help or anything I should know would be appreciated.
 
Talk to someone who solders. They will know what cold solder joints are. Basically, you reheat/reflow a solder connection that looks suspect. Did the amp cut leaving only hum before you changed the guitar toggle switch?
 
Rocker68 said:
Talk to someone who solders. They will know what cold solder joints are. Basically, you reheat/reflow a solder connection that looks suspect. Did the amp cut leaving only hum before you changed the guitar toggle switch?
Click to expand...
Lol... no.... I didn't even have the guitar yet. I was using my old one.
 
Cold solder joint or a tube problem are my first two guesses. I had a Splawn Quick Rod that had a cold solder joint and it would cut out like that. I have been playing well over 30 years and the only amp troubles I have ever had ended up being tube related other than that time with my Splawn. I took it to Jeff Snyder in San Diego who was "the amp guy" and who also built Snyder amps. He figured out the problem quicly and charged me for an hour of shop time.
 

condensed version. Cheapest band aid try this first. You'll have to find a tech in your area. Your tech might check voltage across D9 before doing anything.​



Just replaced D9 with IN4731 1W 4.3V zener diode on my DSL 40C amp that would reliably mute after 10 minutes of hard playing. Ran it for over 6 hours playing on ultra gain channel at high volume through a dummy load without error after fix. Not sure I understand the circuit as I measured about 2.1V across diode before the fix and about 2.6V after, still below 3V threshold, but did not scope signal.
Click to expand...
 
Thank you.... I have a guy that works on guitars and amps. I'll get in touch with him. I was hoping it was something I could've fixed myself.
 
Rocker68 seems to be onto something with this resistor issue and maybe that is known thing.

I'm not an amp tech myself nor an EE.

One thing you can do, now or anytime, while owning a tube amp is stuff like this:

Clean the input jacks and FX loop etc. Use something like Dioxit for electronics, not WD40. Spray the jack (not the socket) and move in and out to clean it.

Clean the tube pins. Again, Dioxit. Spray the pins (not the sockets) and work the tube in and out to clean and lubricate.

Check tubes by tapping lightly on them with a pencil and also looking for s subtle glow. Bright orange or red = bad. No glow = bad. Can you hear the tapping sound through the speaker? = bad.

Plug guitar into FX return (if you have one) to see if problem remains. If it does - you can rule out the preamp section.

Check fuses. Sometimes you would need to open the amp up for any internal. As long as you don't touch anything inside the amp, especially with both hands at the same time, you should be fine.

You can swap preamp tubes while the amp is on. Never do that with power tubes.

But yeah - I'd be leaning toward a soldering issue as well with what you've described. Is it the same amount of time each time?
 
311splawndude said:
Rocker68 seems to be onto something with this resistor issue and maybe that is known thing.

I'm not an amp tech myself nor an EE.

One thing you can do, now or anytime, while owning a tube amp is stuff like this:

Clean the input jacks and FX loop etc. Use something like Dioxit for electronics, not WD40. Spray the jack (not the socket) and move in and out to clean it.

Clean the tube pins. Again, Dioxit. Spray the pins (not the sockets) and work the tube in and out to clean and lubricate.

Check tubes by tapping lightly on them with a pencil and also looking for s subtle glow. Bright orange or red = bad. No glow = bad. Can you hear the tapping sound through the speaker? = bad.

Plug guitar into FX return (if you have one) to see if problem remains. If it does - you can rule out the preamp section.

Check fuses. Sometimes you would need to open the amp up for any internal. As long as you don't touch anything inside the amp, especially with both hands at the same time, you should be fine.

You can swap preamp tubes while the amp is on. Never do that with power tubes.

But yeah - I'd be leaning toward a soldering issue as well with what you've described. Is it the same amount of time each time?
Click to expand...
You know, I never timed it. But it just cuts out, the sound cuts off while the amp still buzzes...I turn it of and on again and there's sound. About 10 minute intervals.
 
311splawndude said:
Then what Rocker68 gave you is probably your culprit. Looks like a known issue with a Diode (D9) that 'mutes' out after 10 minutes.
Click to expand...
That's sounds like it's the issue. Does anyone have any instruction on doing it yourself? D9 should be pretty easy to identify. I have soldering equipment.
 
You would have to know how to discharge capacitors first. Honestly, I'd just find someone who has swapped out components in an amplifier before. No offense to you, but it wouldn't take much to funk something up pretty awful - especially if we are talking about traces on silicone.
 
You must log in or register to reply here.
Back
Top