![](https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/?action=dlattach;attach=867058;image)
Hmmmmm... initial inspection shows no evidence of fire or magic smoke, and the rails are steady on at +/- 25.5V from a good old-fashioned linear power supply buried in the sub enclosure. After an hour powered up, all finals feel slightly warm but none warmer than the others.
Based on specs, I expect this should deliver right around 25W continuous per TDA7296 in AB operation, and this thing has 8 of the little bastards with two in BTL mode for the sub at probably 75W continuous or so. Fukkin-a-diddy! That's $50 worth just in the finals!!!
Now I need to figure out how to do turn-on/un-mute to inject signal & see if they're all healthy... I have an eval circuit in the datasheet, so should be able.
mnem
![Blah :blah:](https://www.eevblog.com/forum/Smileys/default/blah.gif)
Suggest putting the Toronto FD on alert.
![Laughing :-DD](https://www.eevblog.com/forum/Smileys/default/smiley_laughing.gif)
Wise idea, actually. Got it to turn on/unmute by pulling pin 11 & 12 LO, just as suggested in the pinout
here. Start probing around with a jackleg signal injector (plugged iPod into 3.5mm headphone cable with a random ceramic cap soldered to the tip on the other end) and determine that all the analog amplifier chips appear to be working. Notice while I'm doing this the smell of something getting a bit overheated, but not smoky.
Eventually trace it down to a 100Ω resistor trying to unsolder itself that was feeding a 7805. 189 sez "KAAAK! Pin 2/3 Short!" but I can't find ANYTHING ELSE on the board getting hot ANYWHERE.
Due to hassle factor of disassembling the heat-sink assembly, I cheat and use my flush-cutters to separate the VOUT pin from the board... DAMN. Short is on the load side, not internal in the 7805.
![Banging Head |O](https://www.eevblog.com/forum/Smileys/default/bangheadonwall.gif)
Now of course I'm wondering if this fault was preexisting or an emergent property related to my tinkery.
At this point I decide it's time to back slowly away from the bench and go rot my brain a little with some
Doctor Who on Prime... and find THEY DON'T CARRY IT on this side of Niagara Falls.
FUCK. ME. ![Banging Head |O](https://www.eevblog.com/forum/Smileys/default/bangheadonwall.gif)
mnem
*Kix The Beeb in the 'nads, just on GP*