That sinking feeling...

[bkahuna]

That feeling you get when you're two hours into a repair, still miles away from having an accurate estimate, and you're beginning to think the equipment has been struck by lightning...Yay.

Working on a Yamaha EMX660 mixer/amp. Started off as a simple +15v reg replacement. Got the 15 volts going, smelled something heating up and found an IC on the front panel getting exceptionally hot. Cool, I thought, there's the original culprit that took out the regulator. Didn't have a replacement, so I pulled it from the circuit (it's a graphic EQ IC). Fired it up, something still pulling down on the +15 volts. Found another cooked IC far away electrically and physically from the first. Replaced it. While troubleshooting that, I suddenly started getting wacky readings everywhere. Couldn't find a ground reference anymore on the front panel, in fact the ground for the +-15 regs didn't make it off the power amp pcb. Great... pull the power amp board and fix the vaporized ground trace. Fire up, something still tugging on the +15v line. Pulled the ribbon to one of the front panel boards to isolate the problem. Heard a small "pop" and suddenly all the voltages looked ok. Of course both LED meters are still completely lit up, so I have at least one or two more problems to find.

Aye Carumba!!

PS: Just needed to vent. I feel better now!

[jrfrond]

You know what would make ME feel better? Bailing out and calling it FUBAR before the shop loses money. It's either that or, due to our NYC labor rate, give the customer an absurdly high written estimate. Not as a deterrent, mind you. It's just reality. Shop rate = $125.00. With two hours already into it, and figuring another 1-1.5hrs. + parts, we are looking at a $400.00 or so repair, more than the unit is worth. Sure the labor rate is high, but it IS Midtown NYC, and labor doesn't come cheap here. The least expensive rate in the area is $95/hr. However, I digress: in NYC, that unit becomes uneconomical to repair.

[Enzo]

On the other hand, in comparison, probably not as many of John's clients are playing Joe Blow's Road House, just out route 17 a mile and a half past the new WalMart. And making $150 a night. With $1 cover on Friday and Saturday. I do get customer's who have a Peavey XR500 as their PA. At $60 an hour, I have the luxury/curse of working on more stuff further down the food chain.



SOmetimes you have to stop and look at the big picture. When there is power supply problems. Is? When ther ARE power supply problems, you might step back and consider, Uh Oh, what if every chip on here is damaged? I have a GK combo Backline something model that came in and the 15v regs were burnt up. Looks simple enough. Then noticed the ICs on the powr amp had lost their tops. Well OK a couple more ICs, no big. But just because, I pulled the preamp board - the little board along the front that was mounted solder side up. Flip it over and sure enough, every IC on it was blown open, along with a few little e-caps. That hour labor and a few parts repair just blossomed into a new amp for the junk pile.

[g1]

Like Enzo said, consider replacing every IC. I would give an estimate of what I would have charged to replace every IC and the supplies from the start. I went through a powered mixer like you are doing now and they just kept failing till I shotgunned them all. Turned out it had been connected to something 2 prong and got zapped. The blown ground was a giveaway like yours. I should have known better but there's always the first time...