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Old 21st April 2017, 11:38 AM   #4511
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I also recommend MyRef Fremen if you are not afraid of smd parts.
I can recommend Myref Fremen as well even if you are afraid of smd parts. I paid Dario to do the smd stuff. (A real nice job by the way)
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Old 23rd May 2017, 05:30 PM   #4512
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Please help.

It was time to put my MR in a case. While testing one channel, the amp suddenly hummed. I quickly turned it off then upon powering it on again, the DC protect just stays on "protect mode"

Any tips on how to determine whether the LM3886 (or the LM318) chip has died? The LM318 PS is still at ~14v and the Main PS is correct at 32V. I did not use a socket for the LM318 and the last time I tried unsoldering one, I ruined the double sided PCB.
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Old 23rd May 2017, 05:44 PM   #4513
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Check R9. It's the 1 ohm resistor between input and power ground.
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Old 24th May 2017, 05:34 PM   #4514
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Hi Mark

The resistor is fine. I

checked the voltage on the -Vin of the LM3886, its -14v. Does this mean that the LM318 is suspect?

Amp output is stuck at -27. My PSU voltage is at +_29v measured at the psu main caps
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Old 24th May 2017, 06:00 PM   #4515
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Many of the failures are in the feedback loop. check the schematic, you can see that the voltage of the LM3886 inputs would be half the output voltage. Perhaps you could post some photos.
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Old 24th May 2017, 06:01 PM   #4516
atupi is online now atupi  Romania
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I suspect lm318 is defective

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Old 26th May 2017, 06:12 AM   #4517
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Mark : It was the 1R input resistor indeed. I noticed one of the main cap was hot. Turns out I switched the center tap with one of the secondary wires. The boards connect to the transformer via a terminal strip and that's wher I made the mistake. I did not pay attention to the connection since the othe board was working using the same psu. Now that working board has a leaking cap .

Thanks again for the help. Both board are still working after changing only the resistor and the leaking cap.
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Old 18th June 2017, 10:14 PM   #4518
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Terrible news: Mauro is no longer with us.

Mauro Penasa tragically passed away.
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