Fender Frontman

[GHopson]

OK,

First Off (after you stop laughing about the AMP I'm actually troubleshooting) I know that I'm crazy even wasting time on this little amp.... But its come down to the "Principle" of the thing now . I have been out of electronics for about 18 years and I haven't troubleshot in awhile but here goes...

Whenever I turn this little guy on,,,, (After I replace the fuse) ...
1) - I get a Hum...
note ** Pots don't seem to affect the sound Up or Down)

2) - I get a hot smell

3) - Fuse Pops.

After finding this site, and reading a little on some of the postings... I am guessing it is either the output chip (IC PC1188H 20W) or one of the Op Amps (IC DUAL OP AMP TL072).

Any other suggestions (Where to order, Completely different Diag, Whatever you suggest) would be greatly appreciated.

Thanks,

Gary

[oc disorder]

Hi GHopson and welcome to the forum
This will have to be quick or it will disturb the valve purists...!
Assuming the speaker hasn't a dead short well disconnect it and see if things still get hot....
If its still cooking try and see what is getting hot..
As you have observed its often the output chip on rare occasions could be a
failed diode in the power supply..
Try disconecting pin 3 from the output chip this supplies the power..
you may be able to find a wire link to lift to cut the power to pin 3.
I suspect the output chip if the fuse doesnt blow now (with pwr disconnected) time for the chip shop.

[GHopson]

Thanks

Thanks OC .... I Must say that I'm really impressed with the Site .... Heck I've been out of electronics for so long .. I forgot how interesting it could be. I think that you guys have re-ignited an old passion... I could see myself getting hooked in this.

Thanks again,
Gary

[Enzo]

Take the wires off the speaker and connect your DC voltmeter to them and briefly turn on the amp. With a good fuse in it. Is there a large DC voltage there? Like 20-30 volts or somehting?

If so, your power amp chip is blown and needs replacing. Op amps won;t likely blow a fuse.

Fender makes/made a bunch of Frontman amps. WHich model is yours?

[Robert M. Martinelli]

After finding this site, and reading a little on some of the postings... I am guessing it is either the output chip (IC PC1188H 20W) or one of the Op Amps (IC DUAL OP AMP TL072).

Hi and a heart-felt welcome to the forum!

Are you sure the output IC is a PC1188H? I' d say it could be a u(for micro)PC1188H ( should you need to replace it and order a new one ).
Hope this helps
Best regards
Bob