Marshall DSL 100 - Nothing!

[JohnG]

I've got a marshall DSL 100 watt head that when firing it up the other day, it worked alright for a few minitues then dropped out completly. I replaced all the power tubes, and the preamp tubes have been replaced recently as well. The powertubes show signal while biasing on the three pins on the back. I apologize but i am basically new to deep repairing amps and am trying to learn more! I am tired of long waits to get my amp returned from the shop.

Thanks

[Mark Black]

Try plugging a cord from the effect send to return, to prove or eliminate a problem with the normalling contacts in the jacks there.

Also try using the 16 ohm speaker jack (at least long enough to check for output). These amps use the normalling contacts in the 16 ohm jack to pass signal to the other two jacks when it is not in use, and it is pretty common for the contacts to overheat & lose connection. They really were never meant for speaker level signal...

Good luck!

[JohnG]

I checked all of the fuses and tried plugging in the return and send as recommended. I made a mistake when describing the problem, The amp is sending to the speakers, just verrrry very low. with the amp on 10 i can barely hear the amp through the speakers.

[Mark Black]

The amp is sending to the speakers, just verrrry very low. with the amp on 10 i can barely hear the amp through the speakers.

Is that true of all the speaker jacks (16 ohm included)? Sorry to keep harping on that but if it turns out that's the problem then it's effectively like running the amp with no load (a bad thing).

Do you have another speaker cab and speaker cable to try in order to rule those out as problems? Or another amp to try into the existing speaker cab/cable to make sure they are working correctly?

If you do a search of the forum based on "DSL" or "TSL" (a very close cousin) you will probably find a wealth of information on common (and uncommon) failure points in those amps. A lot of the most common stuff boils down to solder joint cracking.

Edit: Oops - never mind about the internal site search - apparently the site kicks out search strings with only three letters. Too bad - that really cripples the searching ability here. You could try it via Google - advanced search - search only in domain: music-electronics-forum.com

Also don't rule out a bad preamp tube even though they have been replaced - bad new ones show up all the time. If you've still got the old ones try some of those in there.

[JohnG]

I have tried the differant speaker outputs and have searched over the circuit board. When i started putting it back together I noticed the soder had cracked where the ohm-selector switch connects, I might have cracked it pulling it apart, Im not sure. But I resoddered it and got it all back together. The amp is making alot of noise, it sounds like an ungrounded guitar, wether the guitar is plugged in or not. Ive tried differant instrument cables, speaker cables, a differant cabinet. I checked the ground wires inside of the amp and they all seem good. any suggestions,

Thanks for your help
John

[JohnG]

BUMP!
I could really use some help if anyone has any ideas!

[tboy]

Oops - never mind about the internal site search - apparently the site kicks out search strings with only three letters. Too bad - that really cripples the searching ability here.

Fixed it; three letter searches work now.

You could try it via Google - advanced search - search only in domain: music-electronics-forum.com

Still a good idea.

[JohnG]

Thank you!