Post a photo of the board. Different revisions of the same model can have different boards.
12v computer supply... Sometimes. Some are too sensitive to the inrush current of some amplifiers.
Have you checked the fuses and confirmed that you had consistent 12v+ across the B+ and ground terminals as the amp tried to power up?
12v computer supply... Sometimes. Some are too sensitive to the inrush current of some amplifiers.
Have you checked the fuses and confirmed that you had consistent 12v+ across the B+ and ground terminals as the amp tried to power up?
The amp is powering up if you have positive and negative rail voltage.
If the LED isn't lit, it may be defective or have a broken lead.
Confirm that you read 120 ohms between the primary ground and the non-bridging speaker terminals.
Confirm that you read 0 ohms between the RCA shields and the non-bridging speaker terminals.
No RCAs plugged in and no power applied for either test
If the LED isn't lit, it may be defective or have a broken lead.
Confirm that you read 120 ohms between the primary ground and the non-bridging speaker terminals.
Confirm that you read 0 ohms between the RCA shields and the non-bridging speaker terminals.
No RCAs plugged in and no power applied for either test
179.x/180 ohm on all 4 non-bridging terminals to ground.
-0.1/0.0/0.8 ohm 4 non-bridging terminals to RCA. Different combinations of RCA inputs produce different values.
-0.1/0.0/0.8 ohm 4 non-bridging terminals to RCA. Different combinations of RCA inputs produce different values.
Changed LED, doesn't turn on. Tested the one I pulled on a breadboard, works fine. DMM showed -0.13v on one of the leads when powered up.
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Black probe on one of the non-bridging terminals, what is the DC voltage on pins 4 and 8 of the op-amps marked 4562d?
-13.07v and climbing on all non bridging terminals vs. pin #4
13.58v and climbing on all non-bridging terminals vs. pin #8
13.58v and climbing on all non-bridging terminals vs. pin #8
You only need to use one of the non-bridging terminals. They're all connected.
The amp is powered up but may be muted.
Black probe on pin 5, red on 14 of the PIC IC, what is the DC voltage?
The amp is powered up but may be muted.
Black probe on pin 5, red on 14 of the PIC IC, what is the DC voltage?
Pin 14 is generally driven from a 5v regulator. Can you see where it's getting it's voltage from? I don't see any 5v regulators.
If they're the LM7805/7905 types, they can be tested by connecting only the input and ground connections (leaving the output leg disconnected). IF they produce the correct output voltages, they should be safe to reuse. Recheck each output voltage immediately after powering up.
-5.10v on output of 7905CT @ U4
4.88v on output of 7805CT @ U3
And the LED is glowing bright red good sir. Now take a bow.
Take a break if you wish or shall we keep going? What to test to ensure correct operation?
4.88v on output of 7805CT @ U3
And the LED is glowing bright red good sir. Now take a bow.
Take a break if you wish or shall we keep going? What to test to ensure correct operation?Attachments
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Negative voltage on the 7905? Measure with the black probe on the ground terminal of the regulator.
If this amp uses sil-pad material, it's best not to reassemble without adding heatsink compound to the transistors.
You need to clamp all semiconductors to the heatsink before testing for more than a few seconds at a time. You can test to confirm that the amp is producing audio out of the sink but only briefly, constantly monitoring the temperature of all components that would normally be clamped to the heatsink (including those under the board).
If this amp uses sil-pad material, it's best not to reassemble without adding heatsink compound to the transistors.
You need to clamp all semiconductors to the heatsink before testing for more than a few seconds at a time. You can test to confirm that the amp is producing audio out of the sink but only briefly, constantly monitoring the temperature of all components that would normally be clamped to the heatsink (including those under the board).
Correction -5.10v on output of 7905CT @ U4.
Everything clamped to heat sink. There was heat transfer tape on the heat sink for the transistors.
Everything clamped to heat sink. There was heat transfer tape on the heat sink for the transistors.
So far so good... clean output on all 4 channels @ 4ohm. Thank you for all your help Perry. You'll be hearing more from me, I'm joining your website very soon.
I don't have anything to join on my sites. If you found something like that, send me a link, please.
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