Marshall DSL401 Modification

[HSH]

Anyone familiar with the overheating mods for this amp? I've got the external fan ready, but to glue the heat sink to the bridge rectifier is going to be more tricky. I'm scared of getting a severe jolt from the caps, and don't know how to safely discharge them without, say, welding a screwdriver to the PCB. Any input would be GREATLY appreciated.

[Andelusion]

Turning the amp on whilst it's unplugged (from the wall) can help to discharge some power, this works for computer power supplies anyway.

But remember the capacitors can hold a charge for a very long time, over a week. I'd consult an electrician first and be very careful!

[HSH]

Thanks for that. It's been unplugged about 2 weeks now, waiting for me to either overcome my fear (whilst being VERY careful) or find out the real info. I know a tech - can't find his number! There was also a site that showed pics of the mod, but all it said was "discharge the caps," nothing more elaborate, darn it. Thanks again.

[Andelusion]

I'm sure if you post somewhere on the harmony central forums someone will know There seems to be a good amount of knowledgeable people on there.

Here's a link to the keyboard section which I have bookmarked: http://acapella.harmony-central.com/...?s=&forumid=18 I'm sure you can find your way to the front page

[red5]

Originally Posted by Andelusion

Turning the amp on whilst it's unplugged (from the wall) can help to discharge some power, this works for computer power supplies anyway.

But remember the capacitors can hold a charge for a very long time, over a week. I'd consult an electrician first and be very careful!

What you want to do for that is to turn it off without turning standby on. Wait a while and then turn standby on so that you don't forget to turn it on the next time you power up the amp.

[HSH]

Thank you, red5. Does it matter that it's been unplugged for a couple of weeks?

[HSH]

It just took courage, you know, fear of the unknown. The fan is now mounted, the heatsink is on the rectifier, and the darn thing is even biased! There is a WORLD of difference in the temperature of the front faceplate. It used to get so hot I couldn't touch it, now I can hold my hand against it indefinitely.....amazing difference. Thanks to all.

[red5]

^^ It shouldn't have been getting that hot in the first place.

Originally Posted by HSH

Thank you, red5. Does it matter that it's been unplugged for a couple of weeks?

Not really, capacitors can still hold a charge. Even draining them as I said, they will still hold somewhat of a charge.

[HSH]

Red5, I agree. I've been reading about it and it seems to have been a design flaw which has since been addressed by Marshall. The models made after 08/2003 (if I'm remembering correctly) are supposedly fixed regarding the heat issue. I just hope the solder joints don't fail. Anyway, it's doing much better now, and I just steered clear of poking around the board. While I was in there I reglued the two Tolex flaps on the inside that had come unstuck, biased it, put it back together and voila! It worked, and runs cooler. It's my first Marshall, coming from a Peavey and Fender past. The DSL401 is, imho, not a bad sounding amp, though there seems to be quite a few folks who diss it harshly. Guess they can afford a Bogner or something. Would be nice! That's why there are so many amps to choose from - it's up to the player as to what they like. Thanks for your help.