Guitar amp outputs out of AUX, but not out of built in speaker

[j4cobgarby]

First of all, I really wasn't sure if this was the correct site to post this on. It seemed the most fitting, at least.

I have a Fender Champion 20 guitar-amp (https://shop.fender.com/en-GB/guita...tal/champion-20/product-2330200.html?rl=en_US). From that link, you'll see that it has a few standard controls on the front, and an built in speaker. It also has a "Phones" output. This is just an AUX output, as far as I can work out.

The other day, I decided to connect that phones output to my _other_ amplifier. Not another guitar amplifier, just a normal desk-amplifier (is that a thing?) -- an amplifier which is on my desk, and has various inputs such as AUX, FM Radio, etc.

Just as an experiment really, I plugged the output of the guitar amp into the desk-amplifier. The desk-amplifier is connected to two loudspeakers. This all worked fine, I heard the guitar perfectly through the loudspeakers. In fact, there was less of a background "hum" sound than I usually get.

The problem is, now the guitar-amp refuses to revert back to using its built in speaker. Of course, I've taken the cable out of the phones output. When I plug the desk-amplifier back in, I hear the guitar through that, but when I take it out, I can't hear anything.

I'm wondering, do you think maybe a fuse was blown? Would the speaker in the guitar-amp have it's own fuse? I'm tempted to open the guitar-amp up and have a look inside to see what's going on, but I don't want to start fiddling around with things without knowing what to look for

 

[Harald Kapp]

The AUX out of the amplifier is meant to ne used with earphones. The internal speaker of the amp will be disconnected when you insert a plug into the AUX socket.
While this can be sensed electronically (cf. your smartphone), chances are that the socket simply uses a mechanical switch to disconnect the internal speaker when a plug is inserted - similar to this one.
Possibly the internal switch is stuck in the "speaker off" position. Open the amplifier and locate the socket. If it is an open type socket, you are lucky and you can see the switch mechanism and repair it (tweak carefully with pliers).
If the socket is encased, you can try to pry it open or simply get a spare socket and replace the old one.

 

[j4cobgarby]

The AUX out of the amplifier is meant to ne used with earphones. The internal speaker of the amp will be disconnected when you insert a plug into the AUX socket.
While this can be sensed electronically (cf. your smartphone), chances are that the socket simply uses a mechanical switch to disconnect the internal speaker when a plug is inserted - similar to this one.
Possibly the internal switch is stuck in the "speaker off" position. Open the amplifier and locate the socket. If it is an open type socket, you are lucky and you can see the switch mechanism and repair it (tweak carefully with pliers).
If the socket is encased, you can try to pry it open or simply get a spare socket and replace the old one.

Thank you! I'll have a go at this tomorrow.