Yamaha emx 88s

SOURCE: No sound from speaker, but works with external speaker plugged in

It sounds to me like you have blown the internal speaker.

SOURCE: peavey minx 110 no sound from main speaker but

Inside the headphone jack is a built in switching mechanism. It is there to cut off the sound to the speaker when you are using headphones to practice quietly. For some reason or another it seems as if this is no longer working correctly. One of the causes of this can be bad solder joints on the circuit board where this jack is located. Another cause is a failure of the jack itself. If you are capable, Take the circuit board out and have a look. Hope this helps.

SOURCE: peavey minx 110 no output to speaker-headphone

LOUD SPEAKER BURNED REPLACE
FREDDY
TIGER ELECTRONICS LTD
ISRAEL

SOURCE: How to remove amp from cabinet? reverb doesn't work.

SOMETIMES the handle screws must be removed as well.

I have taken a lot of these out and the key is to figure out which direction it comes out... MOST are out the back and sometimes a board across the back has to be taken off with four screws to clear a transformer.

FIGHTING getting the thing out when it catches on the Tolex covering is the USUAL problem. Takes patience and sometimes a blade to hold the Tolex back.

USUALLY the speaker baffle stays in place.

SOURCE: Marshall MG100HDFX 100-Watt Amplifier Head. The

You'll have to take it in to get it repaired. From what you described it sounds like you blew the output stage out. You can't run from your speaker output jack into the input jack of another amp. You should go out of the recording out, line out, effects out or in the least case your headphone out. What happens usually is your output transformer short circuits due to a mismatch of impedances. It sounds like you still have a transformer though so you might have gotten lucky. You will need to take it in though. Sorry.