Samson Resolv 65a monitors - blown 220R 1/2w resistor again
Buddy of mine is sequencing and mixing on a pair of Samson Resolv 65a active monitors. Awhile back one of them stopped working. LED on front still comes on, just no sound from the woofer or tweeter.
I had him stop by and drop it off hoping it was something simple like a fuse, loose connection or cold solder joint. Once we opened it up it was clear there was an obvious burnt spot on the amplifier PCB where a resistor used to be.
Looking up the schematics at manual-archives.com I determined that the cooked componant (R9) was a 220 ohm 0.5w resistor and replaced it with the same. A nearby resistor (R7), a 1K 0.25, was scortched a little, so I replaced that one too even though it still showed 0.996 kOhm on the meter.
Reconnected everything and tested and R9 immediately got hot again. Saw/smelled smoke and killed the power.
Starting to suspect (Z1) 15v 0.5w zener and/or (Q21) C2061 power transistor. Hard to test either of these without peeling up all the yellow rubber they pour all over the PCB and desoldering each one by one. Groan, wtf is this rubbery stuff anyway?
SO, any advice for me or experience with fixing amps before I go and make things hard than they already are? I've gone and ordered more zeners and even some 2061 transistors to try and swap out. I have meters, irons, but only the most basic electronics skills, so all comments and questions welcome! Thanks.