Marshall DSL output transformers

[Mars Amp Repair]

Hi folks,
I'm having to replace a shorted output xformer in a Marshall DSL 100. I've heard from this & other sites that the Marshalls are particularly susceptible to impedance mismatches as well as just not being that great of an xformer.

I see the Mercury magnetics version for $150. Is there another good after-market xformer that doesn't cost like that which anyone is aware of? I am a Korg warranty station but want to go one better on that xformer if feasible. thanx, glen

[Enzo]

I can't say that since that transformer came out I have had to replace any more of them than I have something else. SO who knows.

If it is still warranty, a non-factory part will kill his warranty if he ever has to take it to some shop other than yours.

[HTH]

what about the Dagnall OT's that Marshall are using in the HW-series? I had one and it was very well built.

OEI are great too but last time I tried to contact them I got no answer - not sure if Joe is still doing anything with OEI (anyone know?)

[Mars Amp Repair]

Thanx guys,
This amp is under warranty for parts..just wondered...Good to hear that these xformers don't go bad anymore than others...I guess I got a bit mixed up as what was said was that they are less tolerant to impedance mismatches...you hook it up right & all should be fine....I too have not replaced many, either, but have less of a history than most of you out there...thanx again, glen

[Enzo]

I hear rumors like that all the time, and I don't doubt you heard exactly what you said. Just my mileage differs.

Most customers tend to think that anything that happens to their amp MUST be a systematic problem that Fender, or Mesa, or PV or whoever has with that model. SOme guy has a MArshall that needs a replacement on a tranny twice, and forevermore to him Marshall has a problem with those. Never occurs to them it might just be coincidence or some other matter not considered.


Perhaps some amps are more prone to killing OTs, not because the OTs are weak, but because the amps have no flyback diodes to protect the poor OT from loss of speaker load. In that case, weak speaker jacks might be the real problem.

[Amp Kat]

Perhaps some amps are more prone to killing OTs, not because the OTs are weak, but because the amps have no flyback diodes to protect the poor OT from loss of speaker load. In that case, weak speaker jacks might be the real problem.

You know we discussed this and I hear all of the time about OT's and mismatches but I ain't buying it either. Even though at a 4ohm speaker load with the selector set at 16 it does pull a little more current but the tranny doesn't care it just transfers it to the speaker. Opens caused by as you said bad jacks,bad cables or broken plugs and twisted wires. Cabinets wired wrong and amps biased way too hot or even component failures like coupling caps after the splitter or bad bias supply caps can take out a tranny very quickly but those things never come up when buying new tranny's. It's always a poor design or underated product. I'm not saying they cant' go bad under normal conditions but most often theres other problems involved then what their telling you.

[Mars Amp Repair]

thanx guys,
it all sound reasonable to me...in this amp it's obvious that original power tubes that shorted were probably what took out the OT...tho I as well as you all have experienced, the bulk of the power tube shorting issues ususally result in blown screen resistors & other components...not OT's....all good info to have for the record...thanx again, glen

[petemoore]

Rumors

Real hard to tell what really happens.
Bad wire, bad jack, bad plug, wrong speaker ohmage, 1/2 failed speaker 'flexwire' all become double suspect..especially if the other thing in line, the transformer that depends on continuity/load repeatedly fails.
If the correlation between components should be realized by the user, but is very often taken for granted.