Fender Passport pulsating problem

[KCman]

Sorry Enzo I tried to type pages plural. My phone hates me! Anyway, there are a few pages that tell all the test points. They are past the board layout, but not too far. It definitely says 300vdc. I just want to move past that. I'd like someone else to see it so I know I'm not losing my mind. Heh

My tester does enhanced fets isn't that mosfet?
There was one junction on one of them shorted. I checked alot of stuff on the amp board, didn't find anything else. I'll check again with a clear head.

Thanks for the help.

[Enzo]

OK, I found what you were talking about.

[g1]

TP1 does use a different ground than TP2 and TP3, so you have to measure across the cap, like Enzo mentioned.
But if there was a problem at TP1, you would not have the correct voltages at TP2 & 3, so you can move on.
The TP voltages are shown on pg.29 of the pdf, but they do not mention the different ground for TP1.

[KCman]

Thanks guys.
I thought something was strange with tp1 since I was getting correct voltages at tp2 and tp3
I will keep checking the amp.

[KCman]

The 2sk1058 had less than 1 ohm between source and gate, so I replaced it. These are hard to find and I didn't know a cross reference for these. So, I took a chance on eBay and got a pair.(this and it's counter that is) I checked them were my Sencore tg46 (it works for FET I double checked). They both didn't test good, just as the old one. I put them in thinking my tester didn't work. I believe they are both bad, as both have less than one ohm like the other.

Am I correct in this thinking?
Does anyone know where to find the pair of these?

Thanks!

[kanks]

http://www.exicon.info/cross-ref.php much better than fakes

[The Dude]

http://www.exicon.info/cross-ref.php much better than fakes

And just as hard to find?

[The Dude]

Audio Labs of Georgia has them!

http://www.audiolabga.com/data_html/ECX10N20.html

http://www.audiolabga.com/data_html/ECX10P20.html

That said, they're rare and expensive. Be sure to fire the unit up with no speaker attached when you install the new parts to help prevent them from shorting right away. Only hook up a speaker after you verify no DC on the output and all is working as it should.

[kanks]

And just as hard to find?

Just order direct from exicon or get the BUZ901/906 from mouser. Same part made by the same people. Or get fakes up to you ymmv

[The Dude]

I agree about buying fakes- bad idea. That said, Exicon is in the UK. The OP is in the US. Shipping makes it cost prohibitive. The BUZ's are also discontinued. The best I could find for "real" parts is the Audio Labs of Georgia parts I linked.

[nosaj]

I agree about buying fakes- bad idea. That said, Exicon is in the UK. The OP is in the US. Shipping makes it cost prohibitive. The BUZ's are also discontinued. The best I could find for "real" parts is the Audio Labs of Georgia parts I linked.

What about going for a more robust part?
https://www.mouser.com/ProductDetail...52bE%252bDg%3d
Thanks,
nosaj

[The Dude]

I'd be worried about the linearity of the device. The original FET's are made for linear audio amplification. Those are more for switching. There would likely be some crossover distortion.

[Enzo]

More robust? I see your part has a higher voltage, but the same 8 amps. The circuit is only running on 36v rails.

[nosaj]

More robust? I see your part has a higher voltage, but the same 8 amps. The circuit is only running on 36v rails.

So you could go lower than 200v ? I was thinking more robust in the same thinking as being able to handle a higher voltage. Was just thinking their has to be an alternative . But looking at the Audiolabs $10 a chip isn't bad compared to the prices of some of the chips you find in the Behringers Pa's.

+1 audiolabs.
nosaj

[Enzo]

36v means 72v could be across each. so 200v is roughly twice that, a margin I like myself. I don't know where 900 volts would come from to threaten those devices.