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Old 21st March 2012, 04:59 PM   #21
m4ick is offline m4ick  United States
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Haha, guess what? Someone has replaced one of the nuts and the plastic insulator is missing on one of the input jacks. I insulated it but it still didn't solve my problem.

Perry, I opened it back up and I felt the tops of the rail caps. None appear to be vented but it feels as if two JUST MIGHT be a little more convex than the others.. It's virtually undetectable. Could rail caps cause symptoms like this?
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Old 21st March 2012, 05:32 PM   #22
m4ick is offline m4ick  United States
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Not likely, the RCAs are held to the side panel with nuts.

One thing about this amp though is that there is no grounding circuit connected to the heat sink and no screws holding the PCB to the heat sink. The only way the chassis is grounded is because the RCA shields are bolted to the side panel.

I'll see what happens if I ground the sink to negative battery.

OOPS, double post. Left this tab open and it asked if I wanted to confirm form submission.
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Old 21st March 2012, 05:45 PM   #23
m4ick is offline m4ick  United States
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Ok, the main problem I'm having now (hum aside) is that I get a pop when it turns on or off. At one point the amp was not connected to any RCAs and out of the blue the subs popped and it went into protect, I was 3 feet away from the amp so it wasn't something I touched. Power off and back on and it still works. This is really frustrating.

The pops seem so random, sometimes I do not get turn on/off pops and sometimes I do. Any chance that a very slightly vented rail cap could do this? There is also a very small cap (electrolytic not film) connected to - speaker via a large resistor. Visually it looks okay but when I feel it it does not feel as flat as other caps in the amp.
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Old 22nd March 2012, 11:49 AM   #24
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Are you sure that you don't have an intermittent short between the heatsink and one of the semiconductors clamped to the heatsink?

Do you read any DC voltage between the sink and the ground terminal?
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