When the tip becomes damaged, the inner core becomes exposed to oxygen and it deteriorates. That leaves the sharp outer shell that can easily damage the board or components.
Q106.
Q106.
Ok, I did find a little leg left on the driver so I went with the ribbon cable jumper to pin 16 of the TL494C. I now have a good ground to the collector. Should I try to power up?
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Sorry. That was a typo. I went back and edited it. I can confirm I did solder to pin 16 of the 494.
Check the other solder connections on the drivers with the lighted magnifying glass after cleaning the connections with solvent and cotton swabs.
Well it's popping the fuse now when I hook it up. I checked the output transistors and they are not shorted.
Maybe I would be better off buying a new amp?
Maybe I would be better off buying a new amp?
Is either power supply FETs shorted?
Conform 0 ohms to ground from both PNP driver collectors.
Check the DC voltage on the gate legs of the PS FETs.
Conform 0 ohms to ground from both PNP driver collectors.
Check the DC voltage on the gate legs of the PS FETs.
PNP driver collectors 0 ohms confirmed.
Q6 Diode check mode, Red leg on left, black in the center 0.751 ohms Red left, black far right. 0.751 ohms
Red center, black right, Shorted.
Q7 Same sequence as above 0.019 0.019 Shorted
Bummer
Q6 Diode check mode, Red leg on left, black in the center 0.751 ohms Red left, black far right. 0.751 ohms
Red center, black right, Shorted.
Q7 Same sequence as above 0.019 0.019 Shorted
Bummer
Two different meter settings.
If 1-3 on Q7 is less than 52 ohms, the FET is definitely shorted.
If 1-3 on Q7 is less than 52 ohms, the FET is definitely shorted.
Sorry. You're dealing with a rookie here. The above readings were in Diode check mode.
200 Ohms scale now. Q7 1-3 19.2 ohms 1-2 also 19.2 ohms Drain and source are almost dead shorted. 0.02 ohms. I guess that makes sense if the gate is shorted.
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You mentioned an amp that shorted FETs 30 to 40 times in a row. Did you find the cause of that?
You're probably in bed. Thanks for the help Perry.
You're probably in bed. Thanks for the help Perry.
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30-40 FETs all at once. I don't remember the amps make models but when you first start to see an amp, you may not know what sort of failures to expect. Intermittently shorted output inductors were generally the problem. After it happens a few times, you learn how to test to prevent these sorts of problems. It's a rare problem nowadays.
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