Marshall DSL 100 full stack mystery!!!

[peeholestinger]

Hey guys,
Big question that has pondered many. First off, my equiptment is a Marshall JCM DSL 100, purchased in 2004 new. I just upgraded to a full stack, both cabs are 16 ohm marshalls. Everything worked wonderfully until my last 2 show. I should also mention my other guitarst has an almost identical rig w/ only a slightly older marshall DSL 100. The problem: I plug everything in, 8 ohms out of head to both 16 ohm cabs. power on, let it warm up, then when i switch the standby on, i get a quick bit off volume/power, then it goes silent. No fuses pop, no breaker trip. Exact same thing happens to my buddies amp as well, plugged into a different outlet too. Now if we both switch to 16 ohm out to a single cab, the problem resolves itself for both of us and we continue on our merry way. I have talked to techs locally and at Marshall and everyone is perplexed by this. thought maybe I could get some help here. I have yet to plug in the amps at home to test them again but the problem occured at the last 2 shows that were both at different venues. I will be testing the amp this weekend. Thank you for any info you may have on this.

[Alex R]

There's a common problem with these amps when they are played at stage volumes often using the 8ohm output. The ground side of the speaker out is common to all the speaker outlets but when you are using the 8 ohm jacks it is channelled across the the 16ohm socket's earth connection, which makes when there is no jack in the 16ohm socket. This connection is not quite man enough to take the juice and it tends to fry the socket. The solution is to fit a new jack socket on the 16ohm outlet, which luckily is the fairly standard Cliff-type part.

There is a thread on here with some pics that will help, but I couldn't find it just now. Someone will remember I hope, and give you the link.

[peeholestinger]

I thought it may be a problem with it grounding seeing as if i touch the speaker cables when its having its "problem" it get a good sharp zapp! Would switching down to 4 ohms help it at all. either way i will replace the 16 ohm jack, easy cheap fix. Thanks Alex R!

[drewl]

Like he said, the 16ohm jack switch is the ground for the other jacks, so it needs to be cleaned/fixed/replaced.

[Metro]

It's a good idea to add a little run of wire over the 16ohm sockets ground switching tabs, there is no need to have the outer/ground socket switching and it will safeguard from major issues in the future, such as a shorted flyback cap (c46) and blown OPT.