hafler dh-200 issues

[MKG]

alright, so- I've got two of these. both were working fine. I had installed a bridging kit and they worked fine after that, I then decided that I wanted to go back to two two channel amps. removed bridging kit. One is working fine. the other, I decided to go ahead and replace input/output jacks and get it into a similar state as the other one.

Replaced jacks, went to set bias- apparently the resistor that i use to drain large filter caps shorted open because when i went to take out the fuse to set bias, **** arched from my screwdriver to the driver board.

I've currently got a short from my positive to negative output on one channel.

I got ahead of myself and my skills with an oscilloscope, and found that my signal was getting all wonky after my input transistors so i matched and replaced them. this was before i realized that my output was shorted.

also replaced the bias pot.

anyhow, i'm stuck with what was probably the original problem, a shorted output. after a bit of searching i still don't understand how to properly test the output mosfets, or if that is likely my problem.

help, please. @avionic , i could use your guidance again, you're the one who helped me get this amp functional initially.

 

[MKG]

I should probably also note that I’ve also replaced all diodes and caps.

This wasn’t supposed to be a shotgun approach but apparently it’s devolved into one.

 

[zebulon1]

Mofsets and BJT's short in the same way. 01.00 ohms or less between any leg means their shorted.
Check all the components for value except the caps. Resistors can fail high or open.
Remember, once you begin to thrash you induce new issues.
Take your time. Its like a puzzle.

 

[MKG]

Ended up killing one of of the p channel output mosfets.

There is a company that makes new replacements at $30 each, but if you’re cheap like me, this guy on eBay has sets of p & n channel used replacements @ $15 a set. I bought myself two sets, he still has another available.

no affiliation.

https://www.ebay.com/itm/2SK134-2SK...5?pageci=19bb1ab0-9e7f-41e3-ad27-9afca93d4f2a

 

[avionic]

apparently the resistor that i use to drain large filter caps shorted open

Shorted open ? Is it shorted? Or is it open? can't be both at the same time. Open is the opposite of shorted. Just say'n...

 

[MKG]

Shorted open ? Is it shorted? Or is it open? can't be both at the same time. Open is the opposite of shorted. Just say'n...

Good point.
It died and no longer allows voltage to pass through, so attaching it to the caps did nothing.
I should have checked it with a multimeter regardless, so this **** up is *all* on me.

wont repeat that mistake again at least.