Scored this old Sony XM-3046 off eBay and it's cooked. Hoping some EE's and my modest soldering ability can bring her back to life. I took the board completely out and these two parts are the only places that are burnt. Board is fine on both sides.
I'm just going to attempt to fix it because it's not in good enough shape to justify costly repairs. Thanks!!
Looks like the switching FETs in the power supply. Maybe the switcher f'd up and set both of those suckers on when they're supposed to be on complementary parts of the duty cycle. No funny spots around the transformer itself, right?
Quote:
Originally Posted by subwoofery
What I wanted to say is that amps ... sound the same.
Good luck with that. Usually if these go, so does other stuff...kind of cascading in a downward spiral of destruction, and the realease of the magic smoke. I hope that is all it is, but more than likely not. Neat little project though, and I hope you don't have too much money into it.
Coffee did you get my PM about the M88??? I need to know something...
Quote:
The years passed, mankind became stupider at a frightening rate. Some had high hopes the genetic engineering would correct this trend in evolution, but sadly the greatest minds and resources where focused on conquering hair loss and prolonging erections. - Narrator: Idiocracy
NTP50N06 is Motorola's (ONSEMI) new part number. Beware that the ones in your amp have the screw tab insulated and the replacements are not plastic insualted at the tab. Care must be taken when screwing to the heatsink to electrically isolate it from the heatsink, otherwise damage may occur.
Replace all of them and also check those resistors by them, one looks toasted for sure. Then check all your output transistors too to make sure they measure the same with your meter on diode check.
Maybe one day, enough lemmings will fill the trench, and people can cross over to the promised Nirvana.-some wiseguy.
Replace all of them and also check those resistors by them, one looks toasted for sure. Then check all your output transistors too to make sure they measure the same with your meter on diode check.
Those say on them:
MT A3
0N06HD
J615(Motorola symbol)
Quote:
The years passed, mankind became stupider at a frightening rate. Some had high hopes the genetic engineering would correct this trend in evolution, but sadly the greatest minds and resources where focused on conquering hair loss and prolonging erections. - Narrator: Idiocracy
Looks like the switching FETs in the power supply. Maybe the switcher f'd up and set both of those suckers on when they're supposed to be on complementary parts of the duty cycle. No funny spots around the transformer itself, right?
I gave the transformer a good look and it appears ok.
Quote:
Originally Posted by GlasSman
It probably just needs some Intelligentstia coffee.
Maybe that'll bring it back.
I PM'd you back.
Quote:
Originally Posted by durwood
My monitor at works sucks and every photo looks dark, but based off what i can see and what others have posted.
It might be a P50N06. THose are pretty common switching FETS.
NTP50N06 is Motorola's (ONSEMI) new part number. Beware that the ones in your amp have the screw tab insulated and the replacements are not plastic insualted at the tab. Care must be taken when screwing to the heatsink to electrically isolate it from the heatsink, otherwise damage may occur.
Replace all of them and also check those resistors by them, one looks toasted for sure. Then check all your output transistors too to make sure they measure the same with your meter on diode check.
The resistor looks like it just got some smoke on it, but I will replace it just to be safe.
As far as isolating, can I use mica material for that purpose?
The resistor looks like it just got some smoke on it, but I will replace it just to be safe.
Check ALL of the gate resistors. when done power up with a very limited current supply because as Mark said, they could be crashing due to timing error.
Does anyone else think it is strange that Sony would use insulated gate power FETs in this application? The thermal resistance of that package is HUGE! Meaning, even though the die is fairly robust, the package can't draw heat off it fast enough. A 90W part is derated to 30W.
You can replace these with a number of other options in a non-insulated tab. One that comes to mind is the IRFZ44.
Like others have mentioned, you WILL need to insulate the tab from the heat sink surface or suffer the consequences.
If you did not want to bother with mica insulators and running that risk, I suggest you try the IRFIZ48G from digikey. It is also an insulated gate part. These will run you a few dollars more, but, are much more robust than the stock part.
You MUST use a current limited power supply when bringing this thing up for the first time after the transplant. My best guess is that an ouput transistor or two could also be blown. That potentially took out the power supply FETs. But, seeing the crappy FETs they used, this may not be the case.
Ge0
Alpine, Zapco, Scanspeak, Image Dynamics, Critical Mass
Life lesson #1) En boca cerradas no entra moscas! (loose translation: sometimes it is best to keep your fuggin mouth shut and listen)
I wish I could fix all the broken amps in the garage. I can't throw them away, but they aren't really high dollar amps and repairing them will cost more than I paid for them.
Need help fixing my amp **PICS!!**
Linear Mode
