Bridge Rectifier for DSL 401

psphill27 · 10-18-2008, 12:07 PM

OK guys...
I pulled apart my DSL 401 and resolder all the joints, including the recifier bridge as recommended by others. All new Groove Tubes and fuses are good. Rebiased the amp to .80V. Thing sounded AWESOME! Worked for about a month and then no sound again. (I never had these problems the first seven years I owned the amp.

Pulled it apart again...check everything. Hooked it back up...tubes lit up and worked. When I went to check bias...preamp tubes didn't light. Gently tapped the bridge rectifier with a screwdriver and they lit up. Put it back together...played like a champ for a hour. Next day...no sound and preamp tubes aren't lighting up.

I'm convinced that the bridge rectifier is bad and I need to replace it. But, I'm not sure what to get and where to order it. Sent Marshall an email and received no reply. Any suggestions?

Also feel free if you have any ideas I'm missing.

Cheers,
Pete

PS-got to get this thing working. I love the sound and it's my go to recording amp.

JohnH · 10-18-2008, 03:13 PM

I'd say if tapping it made it work again, then it has to be the external connections rather than its internal workings of therectifier.

It gets really hot and melts its joints. You can add fans to cool the tubes, which also makes a big difference to the heat in the chassis. Also stick a small heatsink onto the rectifier with thermal cement.

If its an older one, I think they changed the design to a higher rated rectifier, and Korg/Marshall could advise. Also, its not a very sound-influencing component, it just has to be there and working, so there should be plenty of other highr rating replacement options, including making one from four seperate rectfier diodes.

Final thought - I dont know about this, but the latest lead-free solder, is a pain to work with, but I believe it melts at a higher temperature, so it might work well here.

John

10-18-2008, 12:07 PM	#1 (permalink)
psphill27 Senior Member Join Date: Aug 2008 Location: Virginia Posts: 337	Bridge Rectifier for DSL 401 OK guys... I pulled apart my DSL 401 and resolder all the joints, including the recifier bridge as recommended by others. All new Groove Tubes and fuses are good. Rebiased the amp to .80V. Thing sounded AWESOME! Worked for about a month and then no sound again. (I never had these problems the first seven years I owned the amp. Pulled it apart again...check everything. Hooked it back up...tubes lit up and worked. When I went to check bias...preamp tubes didn't light. Gently tapped the bridge rectifier with a screwdriver and they lit up. Put it back together...played like a champ for a hour. Next day...no sound and preamp tubes aren't lighting up. I'm convinced that the bridge rectifier is bad and I need to replace it. But, I'm not sure what to get and where to order it. Sent Marshall an email and received no reply. Any suggestions? Also feel free if you have any ideas I'm missing. Cheers, Pete PS-got to get this thing working. I love the sound and it's my go to recording amp.

10-18-2008, 03:13 PM	#2 (permalink)
JohnH Senior Member Join Date: May 2008 Location: Wollongong NSW Posts: 780	Re: Bridge Rectifier for DSL 401 I'd say if tapping it made it work again, then it has to be the external connections rather than its internal workings of therectifier. It gets really hot and melts its joints. You can add fans to cool the tubes, which also makes a big difference to the heat in the chassis. Also stick a small heatsink onto the rectifier with thermal cement. If its an older one, I think they changed the design to a higher rated rectifier, and Korg/Marshall could advise. Also, its not a very sound-influencing component, it just has to be there and working, so there should be plenty of other highr rating replacement options, including making one from four seperate rectfier diodes. Final thought - I dont know about this, but the latest lead-free solder, is a pain to work with, but I believe it melts at a higher temperature, so it might work well here. John __________________ DSL401 8412 cab Crate Powerblock 1 x 12 Vintage 30 cab '76 Shergold Masquerader '93 Les Paul Studio '83 Roadstar

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