Hi everyone, and thank's for accepting me to the forum! I'm a long time reader of AAC, but this is my first post!

I'm troubleshooting an AKAI MPD24-drum machine, and it seems the power supply is malfunctioning. I've narrowed it down to what seems to be a blown/shorted mosfet (series pass transistor?), but the problem is, that I can't figure out the exact type, since it's missing any labels I could identify. Only "23 330 J2 6C" on the chip. Maybe someone could spot it?

I'll attach a shot of the power supply board as we. U4 is the spot for the mystery transistor/mosfet.

Thanks!

-Jonah

 

Hi everyone, and thank's for accepting me to the forum! I'm a long time reader of AAC, but this is my first post!

I'm troubleshooting an AKAI MPD24-drum machine, and it seems the power supply is malfunctioning. I've narrowed it down to what seems to be a blown/shorted mosfet (series pass transistor?), but the problem is, that I can't figure out the exact type, since it's missing any labels I could identify. Only "23 330 J2 6C" on the chip. Maybe someone could spot it?

I'll attach a shot of the power supply board as we. U4 is the spot for the mystery transistor/mosfet.

Thanks!

If its a linear regulator; there's no particular advantage from a MOSFET than bipolar - so they probably didn't.

The markings look more American than Japanese - it could be a "house coded" part, so you may not be able to identify it without the service manual.

-Jonah

 

Hi Ian, and thanks for the reply! Indeed it might also be a bipolar transistor, but in any case the drain and source are shorted, and hence my Peak Atlas DCA is unable to identify it.

Any ideas what I could safely substitute the original component with for test purposes?

And yes, I am shooting in the dark, working without a schematic. Akai won't release it.

Thanks!

-Jonah

 

Trace out the schematic then it would be possible to work out what that component is.

 

Sorry about the very messy handwriting... :-/

 

Anyone? Does the schematic make any sense? It almost looks like switch..Or is it a linear regulator, and I've just drawn it wrong? Chances are I've probably drawn it wrong anyway!