ADA MicroTube 200 smoking issues

[PRNDL]

Don't they know that smoking is bad for your health?

The owner said the smoke came from amp and it now goes into safety mode.

Nothing looks burned, and I figured the most common cause would be the power MOSFETs. They are IRF9530 and mouser has the Vishay IRF9530SPBF.

Is it possible to test the MOSFET in the circuit?

If not, it would be easier to replace all the MOSFETs (8 of them) and see if that fixes it.

Does anyone have a schematic?

The owner isn't interested in spending a lot of money on repairs.

Thanks!!

[Enzo]

DO any of them appear shorted? If there are multiple output devices in parallel, remove the shorted ones, and the remaining ones may well be OK. That would allow you to powr it up and test the remainder of the circuitry.

In modern parts, "PBF" on the end means "lead free." Pb being the chemical symbol for lead. Other companies use "G" for green.

The data sheet wouldn;t come up for me, so I don;t know what the S is for offhand, but Mouser sells the IRF9530PBF for $1.08. SO for 8 dollars, why screw around?

Are you sure all 8 are IRF9530? Possibly half of them are IRF530? Worth being sure.

[icefloe01]

The data sheet wouldn;t come up for me, so I don;t know what the S is for offhand..

I believe it means it's a surface mount part.


Eric.

[PRNDL]

I think getting the schematic is the first thing to do, especially since the lettering on two of the MOSFETs is too light to read. Also, I think the real issue may be in the power supply.

www.adadepot.com appears to be a great resource, and the owner offers email assistance.

I'm updating my strategy of "let's replace the power MOSFETs and see" to "Let's ask an expert and test to find out what's broken"

-- i get by with a little help from my friends