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Old 6th March 2012, 08:59 PM   #11
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You take the bottom cover off of the amp. It's 4 or 5 philip's head screws. That's all you need to remove.
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Old 6th March 2012, 10:14 PM   #12
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I dug back there and got access to it.

There are 3 leds lit on four upright boards.
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Old 6th March 2012, 10:23 PM   #13
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Was it distorted when you saw all of the LEDs lit?
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Old 6th March 2012, 11:16 PM   #14
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yep, distorted and lowered output, 3 leds lit on each board.

heatsinks on that end of the amplifier were very hot, even at low volume they were hot.

Low ohm led on as well...

Last edited by Black Frog; 6th March 2012 at 11:18 PM.
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Old 6th March 2012, 11:32 PM   #15
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That sounds like you may either have a defective bias potentiometer or a broken leg on one of the output transistors. It's also possible that you have a shorted output transistor but that would not be intermittent.
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Old 7th March 2012, 01:34 PM   #16
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What's the best way to get all those retaining clips off the heat sink rail without ruining them?

They seem to be rather stubborn just poking around at them....

I pulled the amp from the vehicle and have it on my bench now.
I have a meter, but not a power supply to power it up on the bench.
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Old 7th March 2012, 01:42 PM   #17
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Click HERE.
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Old 7th March 2012, 01:52 PM   #18
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Quote:
Originally Posted by Perry Babin View Post
Click HERE.
thanks, very crafty....
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Old 7th March 2012, 02:48 PM   #19
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I found this interesting.
Although I didn't find any shorted outputs, although I wasn't sure if I would with an intermittent problem, I did notice this on the underside of the board.

This is the solder side of Q102:
Click the image to open in full size.

And a closeup:
Click the image to open in full size.

Is Q102 related to the F/L channel? Wondering if when that heats up sometimes there may be some contact of that solder blob with the neighboring solder point?
At the moment is isn't shorted through the blob, but even with a 10x loop I can't see any clearance between there so it has to be under .001"....
And that location is toward the end of the heatsinks that felt hot to the touch when I checked with the distorted condition.

Last edited by Black Frog; 7th March 2012 at 02:55 PM.
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Old 7th March 2012, 03:01 PM   #20
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It may not be causing the problems that you described but it needs to be removed.

I don't know if this is the LF channel but you should be able to find 0 ohm continuity between one of the speaker terminals and one of the legs of this channel to determine which it is.

Do NOT power up the amp without the transistors tightly clamped to the heatsink.

When you power it up after you reassemble it, I'd suggest that you have nothing larger than a 15 amp fuse in series with the B+ wire.
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