I repaired the power supply and 2 shorted irf640's on this memphis amplifier. However something is still damaged. Regulated is +-15, the power supply runs smoothly without the rectifiers. With the rectifiers in curcuit the amplifier flashes in and out of protection, the amplifiers draws about 2.5amps of current then not. Its fast the ammeter just swings as it attempts to power up. I could use some help identifying the problem in this protection curcuit.
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With driver card still pulled 0.00vdc
With it installed the voltage goes to .003 to .001 as protection flashes.
With it installed the voltage goes to .003 to .001 as protection flashes.
I don't understand. Is that the DC voltage measured directly across the positive and negative speaker terminals AFTER the relay engages?
AFTER the relay engages?
Is the relay engaging then immediately dropping out (very fast double-click)?
Is the relay engaging then immediately dropping out (very fast double-click)?
The relay engages but it does not disengage with the protection flashing. It does shut down regulated voltage and rail, its very fast switching. Is they a way to bypass the protection to see what happens?
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that is with it installed. Should I have it removed for all further testing?
With the driver card removed the relay just engadges once at start up.
With the driver card removed the relay just engadges once at start up.
I'm sorry. I missed the post where you stated that you reinstalled the driver board.
I wanted to confirm that with the driver board out of the circuit and the relay engaged that you had 0v DC across the speaker terminals.
I wanted to confirm that with the driver board out of the circuit and the relay engaged that you had 0v DC across the speaker terminals.
The fault is likely on the driver board. You'll have to check the various driver transistors and low-value resistors near them.