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STA505 Short/smoked on DDX320 v2, salvagable?

STA505 Short/smoked on DDX320 v2, salvagable?

Well, my ddx320 v2 is no longer operational. A few days ago when i powered up the amp w/ the remote, the ps (smps @34v 9.6A 350w) was already on, a loud hum and fizzling noise emitted from the amp. I immediately ran to the ps and pulled the female/male d-plug ac line, and the dc 4 pin molex plug used to deliver dc from the ps to the amp.

As soon as it got to the ps ac cable, the ddx board started to smoke, bigtime. Emanating from the hs on the amp/driver chips. About 1s later i had the molex dc input disconnected (dc supply from smps to the amp).

This was configured with 2x 8ohm 100w acoustic research ar 215 ps bookshelf speakers, and a 3 ohm 160w sony SS-WSB102 on the bass output. Also i had a 50v, 2200uf x4 parallel wired capacitor bank in parallel to the dc out on the power supply. No input from the source was on at the moment, and the volume was at something like -35.

After carefully removing the screws and lifting the board, i saw charred traces and black burn marks right below the sta505.

I shorted all the caps, and removed the heatsink. The back half of the sta505 had literally blown a hole out of it, and it destroyed all the traces on the back side of the chip. It must have shorted to the heatsink, or something internally near the back of the sta505. No arc burns on the sub output connectors. All speakers working fine.

So, i removed the sta505, and short tested the dc input. Both of the diodes are fine. The only visible damage was to the st505 chip. I short tested positive trace from the coil/capacitor/resistor/cap bank to the sta505, to ground, and it was fine.

I was told this configuration was within its limits, but i know it was pushing it. I think the sub had to low of a resistance (3 ohm), coupled with its limit @160w with the sony sub.

Is there any way to desolder the coil, resistor, capacitor, and traces to the sta505/clean them up and epoxy to prevent further shorting, and use the amp as a stereo only device? Like i said, the only damage i can find is the sta505, is it possible for the bass channel to be turned off, the components removed, traces filed off, and have a 2.0 salvaged digital amp?

Or is it garbage?

I understand the risks involved, and know a fair bit about pcb repair, if it just involves removing traces, and components. Testing shorts, resistance, etc. I understand i am liable for any repairs i attempt, and the potential risks associated with self repair, but just wanted a 2nd opinion here.

Any harm/damage that may come, lies only with me and not those who may offer their opinion on what the problem may be, or their opinion on what might fix it.

Any advice is helpful. I'll post some hq pics of the damaged areas tomorrow morning.

I have already purchased a suitable bass amp (rated @ 250w rms 2ohm), and have another d class 4x100w @ 6ohm amp; preamp w/ bass output/crossover; and a dac on the way, but i don't want to throw out my ddx320 if there's any chance it can be repaired to a 2.0 system.
Well, my ddx320 v2 is no longer operational. A few days ago when i powered up the amp w/ the remote, the ps (smps @34v 9.6A 350w) was already on, a loud hum and fizzling noise emitted from the amp. I immediately ran to the ps and pulled the female/male d-plug ac line, and the dc 4 pin molex plug used to deliver dc from the ps to the amp.



As soon as it got to the ps ac cable, the ddx board started to smoke, bigtime. Emanating from the hs on the amp/driver chips. About 1s later i had the molex dc input disconnected (dc supply from smps to the amp).



This was configured with 2x 8ohm 100w acoustic research ar 215 ps bookshelf speakers, and a 3 ohm 160w sony SS-WSB102 on the bass output. Also i had a 50v, 2200uf x4 parallel wired capacitor bank in parallel to the dc out on the power supply. No input from the source was on at the moment, and the volume was at something like -35.



After carefully removing the screws and lifting the board, i saw charred traces and black burn marks right below the sta505.



I shorted all the caps, and removed the heatsink. The back half of the sta505 had literally blown a hole out of it, and it destroyed all the traces on the back side of the chip. It must have shorted to the heatsink, or something internally near the back of the sta505. No arc burns on the sub output connectors. All speakers working fine.



So, i removed the sta505, and short tested the dc input. Both of the diodes are fine. The only visible damage was to the st505 chip. I short tested positive trace from the coil/capacitor/resistor/cap bank to the sta505, to ground, and it was fine.



I was told this configuration was within its limits, but i know it was pushing it. I think the sub had to low of a resistance (3 ohm), coupled with its limit @160w with the sony sub.



Is there any way to desolder the coil, resistor, capacitor, and traces to the sta505/clean them up and epoxy to prevent further shorting, and use the amp as a stereo only device? Like i said, the only damage i can find is the sta505, is it possible for the bass channel to be turned off, the components removed, traces filed off, and have a 2.0 salvaged digital amp?



Or is it garbage?



I understand the risks involved, and know a fair bit about pcb repair, if it just involves removing traces, and components. Testing shorts, resistance, etc. I understand i am liable for any repairs i attempt, and the potential risks associated with self repair, but just wanted a 2nd opinion here.



Any harm/damage that may come, lies only with me and not those who may offer their opinion on what the problem may be, or their opinion on what might fix it.



Any advice is helpful. I'll post some hq pics of the damaged areas tomorrow morning.



I have already purchased a suitable bass amp (rated @ 250w rms 2ohm), and have another d class 4x100w @ 6ohm amp; preamp w/ bass output/crossover; and a dac on the way, but i don't want to throw out my ddx320 if there's any chance it can be repaired to a 2.0 system.



Hi, I'm sorry about that. I think you can think about remove the bass channel chip (the burned power chip), and clean the solder duiring the pads to prevent short circuit. And other parts including caps and inductors are no need to be removed. then setup the DDX to stereo mode, you can use it if there is no other problem.
Thanks ^^

I'll give it a shot sometime when i have a minute to sit down with the soldering iron.

Appreciate the info.
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