ST4151V power amp chip

[nosaj]

I have a ST4151V  chip  I'd like to know how to go about testing it for shorted outputs.

I have the datasheet but not sure I quite get it.

Thanks, nosaj

[Enzo]

From the data sheet, pins 10 and 13 are the outputs, so measure them to either power pin.  This is just a transistor circuit in a box, so test it as if it were individual parts.  You just can't get at all the parts.   I often do that in large amps.  I measure resistance from the red output terminal to the main filter cap hot leads.

[nosaj]

I get about 3megaohms one way and OL with the leads reversed  for both outputs. So I'd say it's not shorted.

Nosaj

[Enzo]

Probably not shorted, but remember you are only testing its output transistors.


And you noted that the V= was common, but the V- had separate terminals, one per channel.

[J M Fahey]

What is the actual symptom?Doesnthe amp blow fuses?
Do you have DC on the speaker out?

As noted by Enzo, these are "conventional amps in a box", intended to ease assembly to manufaturers and simplify servicing by full replacement, obviously they are not meant to be opened and replaced, in fact I guess you want to confirm whether ordering a new one or not, but I know for sure that in certain Countries, notably in Central America (and maybe Cuba?) , there´s Techs who cut the plastic case open, somehow unsolder original transistors and solder new ones to the backplane.
Guess that can be done with TO220 cases, maybe larger ones.

[nosaj]

At first the yamaha piano wouldn't turn on But after resoldering the chip back in I was greeted with piano noise.  When i would play it loud it would cut out and sometimes reboot. 
After lifting the other circuit board  I found the metal dimpled upwards making slight contact with the circuit board. After hammering it down and reinstalling everything. It doesn't cut out or reboot anymore.
Someone had put a bolt in that was too long and it bent the metal towards the board.

Thanks,
nosaj