Marshall DSL100

[speakmanj]

I suspect the mains transformer on an amp I am repairing is faulty. Anyone know the correct resistance of the primary winding? This one is 4.7 ohms. The transformer is a Dagnall D2105. Also, looks like someone has taken the (spade) secondary connections off at some time and soldered the wires back on. Can anyone provide a photo of what the original wiring looked like?

[Mark Black]

Hi speakmanj -

Power transformer primaries can read pretty low for DC resistance and still be OK.

What led you to look there in the first place? Fuses blowing?

You could try the "light bulb current-limiter" trick with all of the PT secondaries disconnected and see if it still wants to draw a lot of power to help isolate the transformer as the culprit.

Good luck!

[speakmanj]

Yes, the mains fuse blows on power up. What led me to think it was the power transformer is that on a Fender Twin I have, the DC resistance of the primary is 14.5 ohms. That's why I posted, I would just like to know what it should be on the Marshall. If it's right, I'll disconnect the secondaries, and see what happens. My second request, for a picture of what the connections should be is related to this. I suspect the wires have been resoldered, and that always makes me suspect miswiring by the owner.

[Enzo]

That would be the first thing I did if I suspected the thing - pull the secondary wires off the circuit and see if the transformer blows fuses all by itself. Then you will know.