ok so heres my problem i have a 1998 fosgate power 500.2 amp that wont do anything but blow my main battery fuse i am looking for someone who can help me trace the problem down i dont want to scrap the amp its probably one of the best amps i've ever had
We need to know if it blows the fuse without the radio turned on. Put a 10 amp fuse in the amp without turning the radio on. Remove it and check it. Let us know what you find out.
The most likely fault is shorted output transistors (transistors marked IRF540 and IRF9540).
On those transistors, measure the resistance between legs 2 and 3 of each individual transistor. Are there any that read near 0 ohms?
On those transistors, measure the resistance between legs 2 and 3 of each individual transistor. Are there any that read near 0 ohms?
ok i measured them im not getting any that measure zero but i do have a couple that measure rather high for my liking
like they wouldnt measure on any resistance setting but the 20k ohms and others wouldn't measure on any setting but 200 ohms
yeah its a pretty crapp meter came from harbor frieght for a total of $2.57 though so it might be the meter
Perry Babin said:
That is the only setting on the meter that has a symbol instead of letters and numbers. Even the 2 dollar Harbor Freight meter has a diode test function. The symbol has a Horizontal line going through a triangle and a vertical line.
When you identify that function, let Perry know, and he can tell you how to check the parts.
it has a diode checker on it i was just sayin i could be gettin the inaccurate readings due to the meters quality sorry for the confusion
Set the meter to diode check.
On legs 2 and 3 of the IRF540s and 9540s, you should read ~0.5-0.8 in one direction. If you swap the probes, you should read something significantly higher. All 540s should be similar to all other 540s. 9540s should be similar to other 9540s. If you find any that read the same from 2-3 no matter the position of the probes, they (or parallel transistors) are defective.
Did you try setting the bias potentiometers to the full counter-clockwise position? If so, does it still blow the fuse?
On legs 2 and 3 of the IRF540s and 9540s, you should read ~0.5-0.8 in one direction. If you swap the probes, you should read something significantly higher. All 540s should be similar to all other 540s. 9540s should be similar to other 9540s. If you find any that read the same from 2-3 no matter the position of the probes, they (or parallel transistors) are defective.
Did you try setting the bias potentiometers to the full counter-clockwise position? If so, does it still blow the fuse?
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