Marshall TSL 122 blowing fuses

funkydunkey · 13-09-2010 8:17pm #1

I am just looking for some help on this. Im taking a look at a friends TSL combo. It died on him a few months ago. And i said is take a quick look at it for him. The main fuse 2A is blowing constantly. I have replaced it a few times. but every time i hit the main switch it dies. I tried it without the tubes and the same result. any ideas what it could be? I'm starting to think it could be the mains traffo. I thought this would be the place to ask. Any help at all would be great. If i can't diagnose it, ill have to make contact with an amp tech in cork or dublin. so if any one has any names that would be great also.

balducci · 13-09-2010 10:00pm

Hi, you are probably using a standard type of fuse which is known as a 'quick blow' fuse. you need to make sure you are putting in a 'slow blow' fuse. you probably won't find these in an electrical store but ebay has plenty.

funkydunkey · 13-09-2010 10:17pm

i should maybe have said that i was using time-lag fuses.
ps. they can be got fairly cheap from the likes of Kelliher Elec and Demesne, both wholesalers.

Anyone have any idea what kind of resistance I should be seeing across the traffo? It doesn't appear to have any obvious marks etc on it. that's not saying it isn't toast of course.

FarmerGreen · 14-09-2010 4:03pm

Transformer wiring:-
http://www.drtube.com/schematics/marshall/tl10-63-02.pdf
The primary is 2x117v in series, measure each one, they should be he same

Chassis wiring:-
http://www.drtube.com/schematics/marshall/tl10-60-02.pdf
the standy switch will isolate the ht side from the transformer,
disconnect one side of the heaters
if the fuse still blows, it can only be transformer.

funkydunkey · 21-09-2010 9:32pm

ok, so it looks like the traffo is gone. it was a dagnall, i looked into getting a replacement but all reviews are pointing in the direction of a Drake or Hammond instead of a direct replacement. any idea where i'd pick one up, any where in ireland do them?

eagle10 · 22-09-2010 5:45pm

funkydunkey wrote: »

ok, so it looks like the traffo is gone. it was a dagnall, i looked into getting a replacement but all reviews are pointing in the direction of a Drake or Hammond instead of a direct replacement. any idea where i'd pick one up, any where in ireland do them?

http://www.tubeampdoctor.com/product_info.php?products_id=127

This may help you

Paolo_M · 23-09-2010 8:34am

funkydunkey wrote: »

ok, so it looks like the traffo is gone. it was a dagnall, i looked into getting a replacement but all reviews are pointing in the direction of a Drake or Hammond instead of a direct replacement. any idea where i'd pick one up, any where in ireland do them?

Firstly, for everyone on the forum in general.

If a fuse blows a second time STOP PUTTING FUSES BACK IN, you can do even more damage that way.
We had a guy here who did just that a few weeks back, and did even more damage on his amp.

Why do you think the traffo is gone? What measurements have you made?
It's an expensive fix and it's not a common failure.

Likely and common causes for the mains fuse blowing are
ac wiring short
rectifier failure
failing filter cap
failing power valves, though I'd expect the HT fuse to go first in this case

Have you checked these?

Personally I would check these over and over, and then test the PT thoroughly and only then decide on replacing it.

Marshall TSL 122 blowing fuses

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