Yamaha EMX212s shutting down

[drewl]

Anyone fix the power amp in one of these?
Any little quirks or common problems?


So, I repaired the power supply in this powered mixer. Standard SMPS.
The service manual is online.

So when the power amp section is connected, the unit will shut down after about ten seconds.

So far everything in the power amp looks good. No obvious shorts or burn marks, all the transistors and emitter resistors measure good.

I need to be able to connect it together while monitoring the power amp and draw on the power supply.
It's a pain due to the modular construction.


I'll post what I find.
Quitting time for now, time for a beverage.

[nickb]

You have to be careful to maintain ground continuity when testing 'out of the box' so to speak. The power amp ground connects back to the mixer board and has to be there for the power amp to work IIRC.

[drewl]

The only ground I didn't have connected were the foil paper used for shielding.
I think that may have to be connected, damn and I took the whole power amp apart already.

Thanks for the tip, I'll let you know if that's the cause.

[drewl]

Crud, grounding the sections didn't help and it blew the supply again.