Rocker 30 Transformer blown? *first post*

[rustyfawkes]

Hello all,

I've been sent here over from the Orange forums because I'm told this gang isn't afraid of ACTUALLY fiddling with things.

I'm going to copy over my query from the other forum to get your input:

I've just joined because I've recently started learning amp repair and have a Rocker 30 "on the bench" right now.

I "inherited it" from a friend who had left it in my garage for a few years after it stopped working and he just didn't want to come deal with it. So now I get to learn by fixing it up!

One of the two mains fuses was blown, so I replaced that, blown again. Replaced that AND the power tubes. Powers on, no sound.

Opened it up, and found this batch of crazy: [img:600:800]http://images14.fotki.com/v380/photos/3 ... to2-vi.jpg[/img] [img:600:800]http://images19.fotki.com/v275/photos/3 ... to1-vi.jpg[/img] [img:800:600]http://images15.fotki.com/v1624/photos/ ... to3-vi.jpg[/img]



So, the blasted out looking jack-zone is surrounding the main speaker out, but I feel like that's coincidental and that's just what was closest to the wires that fried? (btw these fried wires are coming from the SMALLER transformer)

Any guesses as to the cause of this problem? Am I looking at just replacing that transformer? If so, how am I suppose to figure out it's equivocal replacement? There's so little to find about the innards of these amps vs Fenders.

Is it possible the wires just got severed enough by the PCB to short against something and flame out? Should I just trim and reconnect?

Any help is appreciated.

Thanks!

[teemuk]

Am I looking at just replacing that transformer?

I wouldn't do that in random. Measure to find out whether it truly is broken or not.

All that residual carbon is most likely conductive, the burned wires are most likely shorted. There are plenty of issues to address besides finding out whether the transformer is faulty or not. And that's just obvious, visual clues of faults.

...

Next time you turn it on to test things do it while you limit current drawn by the amp and preferably with chassis open so you can immediately spot signs of arcing or overheating components.

[Leo_Gnardo]

What teemuk said. Have a look at the sticky: TAG Light Bulb Current Limiter. Very handy to have when testing suspicious amps. Also a good idea to make up a hi voltage discharge lead, just a resistor & some clip lead wire, to make the insides of your amp safe to work on, as filter caps can retain a charge that will zap you good, or worse.

I'm guessing what we're looking at in the burnt area are the output transformer primary leads. Not a terribly good build to have them stretched to the point they shorted against a ground or near-ground part of the amp. I'd recommend cutting out the burnt section, strip the ends of the wires going to the transformer and measure them with an ohm meter. If you see some reasonable resistances say between 40 and 300 ohms, it's likely your OT is OK. Then you continue by splicing on some new bits of wire so you don't have to stretch the way Orange did, cover the splices with heat shrink tubing, and land those wires exactly where the old ones were. IF on the other hand, you measure open-circuit on those wires, likely your OT is kapoot.

[cbass]

Looks like the wires rubbed against the board till the insulation failed.If those are the primary leads they had a lot of voltage on em.