Yamaha P140 not turning on...ideas??

[zumi]

Hello all,

After returning home from a long trip my P-140 no longer powers on (no display lights, no sounds, nothing). It was plugged into the wall the whole time I was gone.

I have a copy of the repair manual so I opened it up and have verified that 12V is being received by the power(AMP) board. Also, the 9V and 5V regulators are outputting correct voltages when I press the "ON" button. And on the logic(DM) board I've verified that the 3.3V/2.5V and the 5V outputs are at the correct voltages as well. I took a guess that the Master Processor IC chip was the problem so I replaced that, but no luck.

Am I missing something obvious here? Anyone have any ideas? What else could cause the piano to seem completely unresponsive? Thanks in advance.

 

[happyrat1]

Stuck panel button?


Gary

 

[zumi]

Hey Gary, yeah i did a continuity check that the switch is working properly. Thanks.

 

[happyrat1]

Are there any state tables in that repair manual of yours?

Do you have a scope or a logic probe at your disposal?

Are you getting clock signals on all the logic pins?

Gary

 

[zumi]

Thanks Gary,
No state tables in the repair manual, unfortunately. And I don't have the equipment/expertise for the logic analysis you're suggesting, so perhaps it's time to bring it to the shop.

 

[happyrat1]

A simple logic probe/injector costs about $20-$40.

Something like this one would do nicely.

http://www.amazon.com/Elenco-LP900-625-Logic-Pulser/dp/B0002E7X5O

Really all you want to do with it is check if there is or is not a clock signal going out to the CLKIN and CLKOUT pins on each of the chips.

Gary