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-   -   Fender Frontman 15g broken (http://www.diyaudio.com/forums/solid-state/124136-fender-frontman-15g-broken.html)

Jpoole908 1st June 2008 08:55 PM

Fender Frontman 15g broken
 
Hey guys, I got the fender starter pack a few years back that came with a fender squire and frontman 15g. But recently I was playing on my Frontman and it all of a sudden just died out. So I opened it up and saw a blown fuse, went to Radio Shack and got a replacement, however, now when I put in a replacement fuse and turn it on the light doesn't come on and it just makes a humming sound for a few seconds and blows the fuse. Can anyone tell me whats wrong or how to repair it because I'm definitely looking into upgrading to a Line 6 Spider III but would like to try and fix the frontman and use it as a preamp or something. Thx.

nigelwright7557 2nd June 2008 08:48 PM

Re: Fender Frontman 15g broken
 
Quote:

Originally posted by Jpoole908
Hey guys, I got the fender starter pack a few years back that came with a fender squire and frontman 15g. But recently I was playing on my Frontman and it all of a sudden just died out. So I opened it up and saw a blown fuse, went to Radio Shack and got a replacement, however, now when I put in a replacement fuse and turn it on the light doesn't come on and it just makes a humming sound for a few seconds and blows the fuse. Can anyone tell me whats wrong or how to repair it because I'm definitely looking into upgrading to a Line 6 Spider III but would like to try and fix the frontman and use it as a preamp or something. Thx.

I would suspect the output transistors at a wild guess.

Jpoole908 2nd June 2008 09:18 PM

How would I check that? I don't want to go replace it and it still not work.

nigelwright7557 2nd June 2008 09:20 PM

Quote:

Originally posted by Jpoole908
How would I check that? I don't want to go replace it and it still not work.

Check them with a multimeter.
They usually go short cct across C-E if BJT or D-S if a FET.

Jpoole908 2nd June 2008 09:23 PM

Uhhhh...? :bigeyes: :smash:

nigelwright7557 2nd June 2008 09:27 PM

Quote:

Originally posted by Jpoole908
Uhhhh...? :bigeyes: :smash:

If you dont understand then I would seriously recommend you go to an electronics engineer to get it fixed.

You will only end up killing yourself if your not trained.

wakibaki 2nd June 2008 10:36 PM

Quote:

Originally posted by nigelwright7557

I would seriously recommend you go to an electronics engineer to get it fixed.

You will only end up killing yourself if your not trained.

This is good advice.

It sounds like you tried replacing the fuse more than once.

Here's what you could try...

Following this procedure may result in a small fire or exploding component or further damage to the amplifier although this is unlikely, so take care.

Dismantle the thing until you can access the chassis. Put in a fuse and switch on and wait for it to blow.

Quickly DISCONNECT the amplifier from the main supply and feel round the components to identify which are hot. These are the ones you are primarily interested in, although they may not be the only problem.

Careful! They may be VERY hot.

DON'T FIDDLE WITH IT WHILE IT'S CONNECTED TO THE MAINS.

This could be more electronics than you really want to learn.

I'm not actually familiar with this amplifier which may have a dedicated chipset, so this is generic amplifier advice.

The output transistors are the probably the largest black rectangular 3-pin devices, they will probably have a heatsink tab and be bolted to a heatsink or substantial part of the chassis. They'll be physically close to where the wires from the speaker come onto the board. There might be a 3-pin regulator or two bolted to the same heatsink. They can be as big as a transistor.

You should be able to identify the transformer and rectifier circuits by following the mains inlet to the transformer and the outputs FROM the transformer. You're not interested in these (yet). You'll also be able to identify the tone control components by their proximity to the TC knobs, and the signal path from the input socket through the TCs and a few stages of amplification. The problems probably aren't close to the input.

If you can identify the txistors then look up the datasheets. You will see that the pins are identified as S, D and G or E, C and B. Measure across the pins with a multimeter as suggested above.

Or you could keep it for throwing out the hotel window at your next gig and buy another. Probly the best plan for somebody who doesn't know E, C and B.

w

Jpoole908 3rd June 2008 01:42 AM

Yeah I probably won't try that. But thanks anyway. Can anyone give me a price that they think it might cost to repair?

unclejed613 3rd June 2008 02:34 AM

i saw from ypur location ID tjat you are looking for info on a TDA2050, which i'm guessing is the output chip for your amp. to be causing a loud hum and blow the fuse, i'll take a WAG that it's shorted. even though the troubleshooting may be simple, you don't want to go through the learning curve for desoldering the chip and soldering in a new one on an amp you may want working again. especially if the amp is recent manufacture and has lead free solder (usually has a symbol on the back that looks like a stylized CE, or it may have PBF or ROHS or LFS printed in a rectangle on the PC board). lead free solder requires higher temperatures to melt, and the metal traces on the pc board can peel off the board if you're not experienced with soldering. you may want to find a tech to fix it.

the CE stamp means it's approved for sale in europe (which for the last couple of years requires lead free solder), the PBF or ROHS stamp means it has lead free solder.


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