NAD for Diynot (Now with more questions!)

[Diynot]

Was given this amp by a fellow marching band dad. Needs tubes and he says there is some sort of “flash” around the power switch when turned on but said that once on there are no other issues. I have had it out of the head cab and done a visual inspection and nothing looks burned or discolored so it may just be the pilot light/switch itself. Have some JJs coming from Tubedepot. Not looking to drop a ton on tubes until verified safe to play. Planning on converting the old cab into an enclosed speaker cab sometime. First Marshall amp ever. I’m sure a hardwired would be much better, but hard to argue with “free”. Any experiences with these or similar or even things to watch out for as far as simple troubleshooting are appreciated.

 

[lowpitch]

These are good sounding amps and more reliable than the old JCM2000 DSL series from what I heard. I got the DSL100H and regularly push it pretty hard but it just works. Crunch channel does quite a convincing JCM800 impression. Nice clean channel too.
Can't help with troubleshooting unfortunately as I haven't had to do any so far, knock on wood.

 

[Diynot]

These are good sounding amps and more reliable than the old JCM2000 DSL series from what I heard. I got the DSL100H and regularly push it pretty hard but it just works. Crunch channel does quite a convincing JCM800 impression. Nice clean channel too.
Can't help with troubleshooting unfortunately as I haven't had to do any so far, knock on wood.

Good deal. Not sure what I will do with 40 or even 20w but am willing to give it a go.

 

[Diynot]

Also if anyone has any good tips and tricks for getting bud and cigarette smoke smell out of tolex…..

 

[JohnnyCreepy]

Also if anyone has any good tips and tricks for getting bud and cigarette smoke smell out of tolex…..

There’s no other way than a new cab if you looking complete freshness. Retolexing is messy. But maybe ozone treatment could help as people use ‘em for furniture and cars?

About switch arcing. If it has arced, it’s prone to do it again. I’d change pwr and sb switches, but before going there give a read for last two paragraphs about switches and their caveats. http://www.valvewizard.co.uk/standby.html

Have you found schem already? EL34World has dsl40 schem, doublecheck if it is same as yours. https://el34world.com/charts/Schematics/files/Marshall/Marshall_DSL40_60_02_v02.pdf

Nothing exact knowledge on your amp, but I have slight PTSD towards semiconductors in tube amps thanks to my old Valveking.

 

[Diynot]

There’s no other way than a new cab if you looking complete freshness. Retolexing is messy. But maybe ozone treatment could help as people use ‘em for furniture and cars?

About switch arcing. If it has arced, it’s prone to do it again. I’d change pwr and sb switches, but before going there give a read for last two paragraphs about switches and their caveats. http://www.valvewizard.co.uk/standby.html

Have you found schem already? EL34World has dsl40 schem, doublecheck if it is same as yours. https://el34world.com/charts/Schematics/files/Marshall/Marshall_DSL40_60_02_v02.pdf

Nothing exact knowledge on your amp, but I have slight PTSD towards semiconductors in tube amps thanks to my old Valveking.

Thanks for the heads up. I will give that a read.

 

[HamishR]

Psionic Audio on YouTube discusses modern Marshalls from time to time. He is very much worth listening to.

As far as getting rid of smells, the best thing is to clean and leave out in the sun. The smell of cigarette smoke is something I can't stand, having grown up with a chain-smoking grandmother. She put me off smoking for life just from the smell. I have used eucalyptus oil to clean things before and the pungent smell of eucalyptus can crush most odours! It's a very good cleaner too. Use it sparingly on a cloth - it's strong stuff. I use it for getting rid of the sticky stuff from price labels, gaffa tape, velcro too. I don't know how available it is in other countries but I buy it from a chemist here in Australia. One bottle lasts ages.

 

[Diynot]

Psionic Audio on YouTube discusses modern Marshalls from time to time. He is very much worth listening to.

As far as getting rid of smells, the best thing is to clean and leave out in the sun. The smell of cigarette smoke is something I can't stand, having grown up with a chain-smoking grandmother. She put me off smoking for life just from the smell. I have used eucalyptus oil to clean things before and the pungent smell of eucalyptus can crush most odours! It's a very good cleaner too. Use it sparingly on a cloth - it's strong stuff. I use it for getting rid of the sticky stuff from price labels, gaffa tape, velcro too. I don't know how available it is in other countries but I buy it from a chemist here in Australia. One bottle lasts ages.

Thanks for the heads up. I have been watching a lot of Psionic stuff lately. Pretty good content. Watching him makes me want to rip the guts out of this thing and scratch build an amp. I know PCB is easier/cheaper to manufacture, but seems engineered to not be as serviceable like many modern things. This coming from a forum based upon PCBs seems a bit of blasphemy I guess. One thing I have not found on any PCB amp repair videos is how/where to discharge the caps. Worries me a bit.

 

[Diynot]

So, a question for the amp building brain trust, I would like to do a simple mod to move the bias probe contacts to external jacks and the bias trimpots to external pots/knobs (like the newer dsl40cr has) Are there any voltage considerations I need to worry about with the bias potentiometers or even the wire I use to connect the external jacks? Do the potentiometers need to be insulated from the chassis? Relevant schematic points. CON5 are the probe points


And just to be sure, a 2mm banana plug socket would be what I am looking for if I wish to just stick a DMM probe in for the measurement right?

 

[pbrommer]

1. Bias is usually carrying -30 to -50 volts DC. Make sure you have a 1 to 2 watt potentiometer. Use a good quality brand as well - Alpha is fine.
2. You won’t need to insulate them (the bias potentiometer), but could if you want piece of mind. I never did and most major manufacturers didn’t.
3. Yep, 2mm banana jacks are just fine. As long as the probe fit and hit the metal piece, you’re good.