Hey everybody,
I recently got this little Fender Frontman 15R project from a nice fellow that had an ad in Craigslist. Free. Sweet! He told me it wouldn't come on and that he had poked around looking for an obvious short, but didn't really have the knowledge nor resources to thoroughly inspect it.

Since I know just about enough about electronics to get me into trouble, and I had just purchased a multi-meter, I brought it home and took the amp apart. Now I have been studying on how to make low-power LM386 style amps for a few months, but have yet to start a project.

Once I got it home I plugged it in and as expected, I got no "On" light and no sound whatsoever.

I got the back off it, I poked around inside and wiggled a few wires, but didn't see anything. I put the back back on and plugged it in, turned it on and the light came on, and normal-sounding hum came from the speaker. Plugged one of my guitars in and got nothing but hum. So, off came the handle and the rest of the hardware necessary to pull the circuit board stuff out. As I was checking the wire connectors on the on/off switch, the ground wire just popped out of the connector. I don't know, but suspect that this amp has been messed with inside since sold new. The bare wire was less than 1/8 in long when crimped. No wire was left in the half-crimped connector. So I replaced the connector with a new one. As I was taking one last look inside and getting it ready to button back together for a test run, I found this:

 The chip in the circuit board (Upper right) and the solder on the metal cover.

From the other side:

So, is this silly looking wad of solder on the cover of the jack from the factory, or someone needing to ground the already broken board? I would like to get everyone's suggestions on how to best go about fixing this thing. Scrape to bare copper and try to wire in a conventional jack, or something else? I have very little money to put into this thing, so I might wind up scrapping it and just using the pots and other bits for home-made cigar box amps. The only other amp I have is a Micro-Cube, (Love it!) My soldering skills are fair to good. I really don't want to scrap it since it is in otherwise very good shape. What would YOU do? Would you fix it, and if so, how would you fix it?

Any suggestions would be VERY much appreciated.

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Good luck!  Ping me when you are working on it, interested in how it works out!!

I had a couple small amps that quit playing(a Behringer and a Crate). The usual suspects are cheap jacks or burn marks around solder joints to the main chips, jacks, switches or output capacitors. Also, the power trannies will not last long on most of these little amps.

I put a Ruby Amp in the little Behringer with the 6" speaker and it works great, sounds great too.

The Crate became a Dual Chip Ruby Amp that I designed fro a couple other circuits, still working on that one for the right results.

 Third try to post this. Not nearly the post it was though,,,

Thank you very much for that input Paul! I thought about trying to build a ruby or some other LM386-style amp and install it. I used the search function here, but didn't find any posts that had a DIY that laid it out in detail how to do it. One might be here, but frankly, I suck at "Search".

  I've spend a fair amount of time on the Run Off Groove website and others like it. Lots of useful information and hieroglyphics out there. I plan on trying some more to save this Frontman because I love tinkering, and I am teaching myself this stuff and just because. Paul, if I cannot save it, am I right in assuming that the pots would be useful in making a few cigar box amps? Looks like a fair amount of other stuff to salvage for later use...

ROG is a great site. You can use the pots and jacks if they are still good.

BrianQ could probably make you a Ruby amp board to put in that cab, they are supposed to emulate a Fender Champ amp and even though it's only .5watt to 1watt output, it's loud enough for my wife to tell to turn it down from the living room.;)

Thanks for the info for the pots, your amp and BrianQ. I am just waiting until my favorite shop to open so I can buy a pointy soldering tip and a few other things and I'll mess with this Frontman trying to get it fixed. If not, salvage time. I already have an LM386 chip, or facsimile that I bought a few days ago. I have some salvaged boards that I am going to see if I can scavenge enough to build a primitive amp from. I will be wanting to talk with someone about me buying some PCBs and other things. Does he have a store?

 Anyway, Thank you very much!

Ray

Thank you very much BrianQ! I have learned a lot from your posts here. I've learned a lot from you, Paul, John Sawyer, Uncle John, Pick, and a bunch of other kind folks here. While I am at it - Thank you ALL!

Nice place you got here.

Ray

I’m actually in the process of ordering some LM386’s, I just reverse-engineered a Smokey “Supro” high gain amp on Friday? Pretty close to one of the circuits from the LM386 data sheet? Definitely a step up from the regular Smokey?

 Hi there, Brian!

Sounds cool. That's what I am trying to learn, as a matter of fact, I'll be trying one of your designs that you posted here. If that is OK with you. Glad to finally tell you thanks!

Knock yourself out, that’s why they’re here? I believe I have 3 or 4 layouts in the “Home made amps” & “It goes to 11” groups?

Cool! Thank you!

You and your schematics have probably taught me more about how to build this stuff than anyone/thing.

 Ray

:D

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