Wacky Fender Amp Problem

S

shinyprize

New member
So, I bought an old Fender Stage 185 solid state amp off a band that was breaking up and moving out of our studio for $1. It didn't work. Well, you could BARELY hear something if you cranked everything up to 10, but I mean BARELY.

So I messing messing around with it and discovered that if I plugged a cable into the Ext Speaker jack and into the input of any other amp (bass or guitar), the internal speaker would come to life and work fine. The other amp didn't even have to be on, just plugged in.

I've never had something like this happen, pretty strange. Any idea what it might be. I'm looking for an easy DIY solution as I don't want to spend much on this amp as it will be a backup at best.

Any help is appreciated. Thanks-
 
Re: Wacky Fender Amp Problem

Welcome to the forum.

Is the internal loudspeaker array hardwired at the amp chassis end or connected via a socket? Seems to me that you have a weak or dirty connection in the signal chain. Try cleaning out any jack sockets and look for dried solder connections on the relevant area of the PCB.

SAFETY FIRST - Remember to ground the amplifier before poking about inside it.
 
Re: Wacky Fender Amp Problem

+1
but i don't think plugging any kind of speaker out into the input of another amp is a very good idea.
 
Re: Wacky Fender Amp Problem

Funkfingers said:
Is the internal loudspeaker array hardwired at the amp chassis end or connected via a socket? Seems to me that you have a weak or dirty connection in the signal chain. Try cleaning out any jack sockets and look for dried solder connections on the relevant area of the PCB.
Click to expand...

The internal speaker is connected via two standard speaker wires, not hardwired. Thanks for responding-
 
Re: Wacky Fender Amp Problem

gibson175 said:
+1
but i don't think plugging any kind of speaker out into the input of another amp is a very good idea.
Click to expand...

I forgot to mention that it also works when I plug it into the input of my mixer, but the mixer has to be powered on, not just plugged in. Thanks for responding.
 
Re: Wacky Fender Amp Problem

Yeah, it sounds like the input jack has a broken solder joint. This is so common with mass produced amps that it's the first thing to check......and it's almost always the culprit.

Over time, the cord gets stepped on and it cracks the solder joint. You probably don't need to replace the jack. You only need to re-wet the solder connections where it meets the board.

Besides the inputs, another culprit is sometimes the FX loop jacks. They get oxidized and lose their connection to the circuit. It puts an open circuit between the preamp and power section. Spray the FX loop jacks out with contact cleaner and rub them out with a Q Tip. Do the same on all the amp's jacks.
 
Re: Wacky Fender Amp Problem

Funkfingers said:
Is the internal loudspeaker array hardwired at the amp chassis end or connected via a socket?
Click to expand...

Just to clarify.

On some Fender amplifiers (for example, the ubiquitous PR246 Hot Rod Deluxe), the cable for the internal loudspeaker has push-on spade terminals at one end and a quarter inch jack plug at the other. On an old Champ, the cable still has spade connectors on one end but the amp chassis end is hard-wired onto the component board.
 
Re: Wacky Fender Amp Problem

Gearjoneser said:
Spray the FX loop jacks out with contact cleaner and rub them out with a Q Tip. Do the same on all the amp's jacks.
Click to expand...

I'll give that a try. When you say "contact cleaner" do you mean a specific type/brand? Or will rubbing alcohol work just fine?

And thanks for your rsponse. If this works I'll be very happy:)
 
Re: Wacky Fender Amp Problem

Contact Fender's customer service ( customerrelations@fender.com ) and they'll email you a copy of the schematics along with the manual as well. I just got a Studio 85 over a week ago and they were gracious enough to send me those.
 
Re: Wacky Fender Amp Problem

Don't use rubbing alcohol...it's mainly water.

Try Deoxit or maybe radio shack brand contact cleaner.
 
Re: Wacky Fender Amp Problem

Let us know if it works.

I thought my Vox Valvetronix head was in need of repair for two years, until I saw a thread on here where StratDeluxer suggested I deoxidize the FX loop, DI, and any other jacks. I was so elated when the amp instantly came back to life.
 
Re: Wacky Fender Amp Problem

Thanks for the responses guys. Sounds like that deoxit is the way to go. Its a little pricey- like $20 at Guitar Center, and money is tight so it will have to wait a moment. As soon as I get it and try it out I will let you know how it worked out-
 
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