Power Acoustic SL3400D

All power supply fets are shorted from legs 1 to 2 in this amp..

On the outputs 1 of the high side fets and 1 of the low side fets are shorted across all 3 legs..

Since only 1 high side fet and 1 low side fet is shorted can I pull the rest of them
Out of the board and test them and use 5 of them for the low or high side and just order 5 of them or should I replace all 10 of them ?
 
I have this exact amp as well and it too is also under repair. Is there any way I can ask you to take pics of the FETS. Mine was refurbished before several years ago and I have a feeling that one of the FETS shouldn't be there. There is a single FB42N20D between the rest which are FB31N20D 's. But to answer, I recommend replacing them all at once. Like Ian said, it's cheap. Plus it'll save you a ton of headache since the others would likely blow shortly after reinstalling if you don't change them all.
 
Anyone have any suggestions on this amp ?

Is there any upgrade to the protection circuit in this amp and the clones like it ?

Wondering since every amp I see like this if the outputs blow the protection doesn't kick in and the amp also blows the power supply fets every time the outputs short ..

And also any fix for the loud turn off pop in these amps ?

Every amp like this that I've seen there is a loud turn off pop
 

Perry Babin

Member
Paid Member
2003-11-20 11:01 am
Louisiana
www.bcae1.com
Are you switching off remote while B+ remains at 12v? If so, there should be no pop.

You can reduce the voltage divider threshold resistor to lower the protection circuit threshold for shutting down. In the attached photo, R198 is a 150 ohm. It was originally a 220 ohm. It may be possible to reduce it further (I've gone as low as 100 ohms in some amps).
 

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Hey guys, just for S&Gs, I purchased one of those cheapo EBay DIY DSO 138 oscilloscopes (with an "upgraded" 10:1 probe) and a $4 DMM. I searched high and low on YouTube for a serious comparison but found nothing. There are a lot of people on big time budgets or just plain old cheap. I figured I could help them out by providing them results. Not 100% sure where I'm going with this project but I need a hobby. My PA amp was just sitting around collecting dust. I also had the thump when I had it installed in my Suburban. Interestingly, when I reinstalled it in a Scion tC, it only thumped when you had the car on ACC and listening to music then turning it fully on. If you simply cranked it up from OFF, it didn't thump. I didn't put too much thought into it to figure out the "why" portion. That'll be another project to tackle to see if there's a noob way to stop it.