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Old 22nd October 2007, 02:02 AM   #1
up2me is offline up2me  United States
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Default amp trouble please help

I am new to the forum here so i hope i am posting right. Well turned on the car today and speakers started to go pop pop pop in and out really fast. I dont know if the amp is fried or not. Obviously there is something wrong but i dont know what.

It is a ppi pc2100 (the older gray metal finish) i was running it at 4ohms on some pioneer 720prs 6 1/2 components. The amp was turned up a little past half way. So i dont think i was over driving it. No bass boost at all. I took the amp apart and saw no black burn spots or anything. The power light remains green and the amp does not go into protect. Does anyone have any opinions on the problem? I searched the forum and did not find nothing on this problem. Thanks to everyone
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Old 22nd October 2007, 05:53 AM   #2
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Don't power up the amp without having the bottom cover screwed town tightly on the amp. If you do and the fault is causing excessive current draw, the power suppy FETs (and other components) can fail within seconds.

With the bottom back in place, connect a speaker (not the ones in the vehicle - preferably a woofer) to each channel and power up the amp. Hold the speaker wires in the terminals but don't clamp them so you can quickly pull the wires out if the speaker pulls in or pushes out. Touch only the insulation, not the copper of the speaker wires. Does the speaker pulse like it did in the car?
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Old 22nd October 2007, 04:02 PM   #3
up2me is offline up2me  United States
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Thanks for reply. It will take me a couple of days to be able to test this. Working 14 hour days this week. So you are saying just to stick the speaker wire in with only the insulation touching correct? What can i expect if the speaker does or does not pulse with this test? Thanks for all the info and trying to help me out
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Old 22nd October 2007, 04:52 PM   #4
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When you stick the speaker wires into the speaker terminal, the copper of the wire will have to make contact with the speaker terminals but you must make sure that you only touch the insulation. If 'you' make contact with the copper wire, you could receive a shock.

If the speaker pulses with no RCAs plugged in and only the test speaker connected to it, it probably has shorted output transistors.

If it does not pulse, there could be a fault in the wiring in the vehicle.
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Old 22nd October 2007, 05:36 PM   #5
up2me is offline up2me  United States
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Ok i understand now sorry i am new at this. I have uplugged the rca's at the time and the sound did stop. So could this mean that nothing is wrong with the amp. No fuses were blown in the power wire, solid ground. Thanks for helping me on this
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Old 22nd October 2007, 06:40 PM   #6
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You need to check the shield ground of the RCA cables.

Unplug the RCA cables from the amp.

Set your multimeter to ohms.

Touch one meter lead to the outer shield ground of the RCA cable and the other meter lead to a known good chassis ground. You should read approximately 0 ohms. If you read more than ~10 ohms, you may have an open shield ground on the head unit.
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Old 22nd October 2007, 09:55 PM   #7
up2me is offline up2me  United States
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Thank you for all your help I am going to try this when i can Thanks again I love this amp i hope nothing is wrong after all
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Old 22nd October 2007, 10:25 PM   #8
ppia600 is offline ppia600  United States
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You should also try to find the cause of the problem if there is no shield ground. It could be the rca cables being faulty or the internal ground solder points in the cd player.
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Old 27th October 2007, 03:06 PM   #9
up2me is offline up2me  United States
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Well I finally got a day off and checked out the rca's like you guys suggested. As i took off the trim i discovered what i did. I thought i had tucked everything nice and neat when installing but to my surprise
I screwed the trim piece screw right threw one of the speaker wires.

So it grounded out right there and blew the amp. The protection never came on in the amp. Isn't there a protection circuit for this in this amp? Thanks guys for the help
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Old 27th October 2007, 04:46 PM   #10
ppia600 is offline ppia600  United States
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It may have been the common lead for both channels and could have shorted output transistors as well as power supply rectifiers or switching fets. You may have to pull the amp apart and start checking transistors.
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