Yamaha TG100 - No ouput

[LoFi-Ninja]

I found a Yamaha TG100 Tone Generator in the bin.



Other than line out, it also has a audio in and headphones out..

I can hear whatever I inject thru the audio in at the headphones out, but not at line out.
I get no sound from the synth module itself from line out or headphones out.
I'm using a drum machine as midi master, and I can see that the TG100 is "making sounds," because the display also works like a bar graph VU meter...

I've disassemblied the unit, and there where no moisture inside but I cleaned it anyways with alcohol. (I've fixed MANY cellphones from corrosion / water damage this way)

Theres no obvious malfunctioning components.

And I don't have an oscilloscope..   

[Circuitbenders]

does the display actually act like an audio VU meter for the output or is it just indicating that its receiving midi data?

[LoFi-Ninja]

It looks very much like it's a VU meter. But it could just be indicating midi data. But it seems to be VU. Like, if I play a crash cymbal or HH it peaks, but if I play bass drum it stays rather low.

I'm going to change the opamp in there and the output transistors for starters. And look for solder cracks when I find my magnifier.

Also, I've got the "Quick start guide" but not the real manual for it, nor the service manual. And the quick start guide is not telling me anything about what the display really is indicating.

EDIT: Went over it with magnifier. No cracks. I don't have the right opamp.

[Circuitbenders]

This is where the japanese Yamaha manual archive is useful

http://www.yamaha.co.jp/manual/english/

they have both TG100 owners manuals but not the service manual.

You probably don't need the ezact op-amp. If you find the datasheet you'll probably find theres a few usable replacements

[LoFi-Ninja]

Thanks alot I didn't know that one..

Just checked the manual. It is displaying MIDI note velocity..

[LoFi-Ninja]

Wooo.. I found something called DEMO Play. ALL OUTPUTS are working fine. Crappy piano brass band music comming out of speakers..

So this could be a really bad thing thou.. It leeds me to believe that some microcontroller is dead.

[Circuitbenders]

Or theres some esoteric midi control parameter in the system setup that you would never ever normally use thats setup wrong. Something stupid like 'local midi output off' or something equally useless.

i'm assuming you've done a factory reset.

[LoFi-Ninja]

i'm assuming you've done a factory reset.

Of course. I thought that was to obvious to even mentioning  And I've re-checked all the parameters.

I've got to get me an oscilloscope. Never got one when you need it