Checked out a car amp. Not blowing fuses but is blowing inline fuse. I opened it up and found at least one bad transistor.
I am a novice but am expecting to find rectifier issues.
The blown IC is a Fairchild K0138. I could not match those numbers. The next set of numbers is FQP50N06. That comes up as a fet. Would that also be rectifier? or is that an out put?a few pairs of leads from toroidial go to these fairchilds. That is what I found at a glance. Am going to se the amp tomorrow.
Thanks!
I am a novice but am expecting to find rectifier issues.
The blown IC is a Fairchild K0138. I could not match those numbers. The next set of numbers is FQP50N06. That comes up as a fet. Would that also be rectifier? or is that an out put?a few pairs of leads from toroidial go to these fairchilds. That is what I found at a glance. Am going to se the amp tomorrow.
Thanks!
What's the circuit board designation (IC..., Q...) for the blown IC?
If it only blows the fuse after remote voltage is applied, it likely has a problem in the audio section (likely shorted output transistors). The rectifiers rarely fail. They should be marked ESC25M02D. Their circuit board designation should be D761 and D762.
The FQP50N06s are the power supply FETs. If it blows the fuse with only B+ and ground connected, they may be defective.
Did you find any shorted output transistors (IRF540, IRF9540)?
If it only blows the fuse after remote voltage is applied, it likely has a problem in the audio section (likely shorted output transistors). The rectifiers rarely fail. They should be marked ESC25M02D. Their circuit board designation should be D761 and D762.
The FQP50N06s are the power supply FETs. If it blows the fuse with only B+ and ground connected, they may be defective.
Did you find any shorted output transistors (IRF540, IRF9540)?
The blown part is an FQP65N06? If so, then you must replace Q742-744 and Q752-754. You amps need to check all of the 22 ohm gate resistors, Q741 and Q751.
After removing the 6 power supply FETs, power up the amp and measure the DC voltage on the solder pad for each of the power supply FETs.
Did you check the output transistors? If not, you need to do so before ordering any parts.
After removing the 6 power supply FETs, power up the amp and measure the DC voltage on the solder pad for each of the power supply FETs.
Did you check the output transistors? If not, you need to do so before ordering any parts.
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