Im working on a Memphis St-16 500D I replaced the Power fets due to being toasted which were unreadable with the inf3205 just like what the st-1000D uses powered up the amp I felt confident that was the problem the red protect turns on right away and then itll dim then go bright in cycles any suggestion if it could be the Output fets or would you suggest checking the driver bjt's first 1266 ?
Is there any DC voltage on the tabs of the output transistors when it tries to power up?
Does it power up with the audio driver board out of the circuit?
Does it power up with the audio driver board out of the circuit?
I will pull the driver board and retest the amp thanks perry im not sure what you mean by tabs the metal pcs above the output transistors casing? If so how do I test that? I used Dows Silicone put everything back together before testing and used kryptonite in between the heat sink where the insulator was badly burned and I had issues with the screws being seized so that's why I thought I would get suggestion before tearing everything back apart again for testing
The metal tab on the case of the transistor that sticks up above the plastic body.
Black probe on amp ground. Red probe on the tab of all output transistors.
Black probe on amp ground. Red probe on the tab of all output transistors.
they all pass current also with the driver board out I don't have the on light (grn) I also tried testing the led for power and is not showing any voltage when powered the relay click on tho you can hear that
I also tested the led separate and it lights up (grn) I found a couple BJT 1266 shorting so ill swap those out tomorrow as far as the led light goes im guessing another bad component I just don't know where. Correct me if im wrong when the driver board is disconnected out of the amp and powered the green light (power) Should still be lit
I went ahead swapped out the bjt's on the driver board all 3 (A1266) powered up the amp again now I have the green light and the red light pulsing any other suggestions where to look next?
I'm not sure what you meant in post #5. If you have DC on the tabs of the output transistors with no driver board, there is a problem.
Sorry I have passing current as in cont. throughout all transistor tabs ill check for volts with the amp disconnected also I noticed when I run the +/- wire the red protect light blinks for one second before I connect the jumper wire to the remote turn on
All of the center legs (tabs) of the outputs are directly connected. You can see this on the board.
are you saying power the amp up and test the metal tabs with the circles above the plastic body have no voltage change on the meter with the amp not powered is that what I need to check?
Swapped out the IRF640's to matching pair now the lights are blinking back and forth and there is noise coming from the coil it sounds like or the big capacitor near where the IRF640 is
With the driver board out the relay clicks after 3 seconds and no protect light (red) or power light (grn)
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