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Old 10th May 2008, 12:52 AM   #1
shagone is offline shagone  United States
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Default interresting amp question

i have an older model smaller 2-channel earthquake amp that i'm working on (black with gold emblem) that powers on and outputs audio on my bench when i run it through a 2 ohm current limiting resistor. when i try to power it on directly without the limiting resistor the power led flashes on and off every couple of seconds and never stays on. it also causes my test head unit that is connected to the same power supply to flash on and off.

What could be the cause of this? i pulled the board and it has some questionable solder joints but i tried to touch most of them up and it still flashes on and off.

has anyone ever seen this happen before?
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Old 10th May 2008, 03:24 AM   #2
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Your power supply is a SMPS I bet.
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Old 10th May 2008, 05:35 AM   #3
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Sounds like your power supply is too weak to power both the deck and the head unit a t the same time when running a 2 ohm load, I would try a bigger power supply before your start looking for problems.
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Old 10th May 2008, 09:50 AM   #4
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How much current is it pulling through the resistor?

If you're using a head unit for your signal source, you should get a small, dedicated supply for it. A computer power supply will work. It's a pain to have the head unit reset every time you cause the 12v power supply to shut down.
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Old 10th May 2008, 01:59 PM   #5
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It's more likely that the supply (SMPS?) doesn't like the highly capacitive load the amp presents; not so much that it is under powered.

I have some 12v 12A switching supplies and they do the same thing if I try to connect a car amp directly to them. They work fine if I insert a 0.1R resister in series with the power wire.
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Old 10th May 2008, 03:08 PM   #6
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The Earthquake he described is from the 'Thrust' family and it's PWM.

Hope that helps.

- Matt
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Old 10th May 2008, 04:46 PM   #7
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Sorry, I didn't mean the amps power supply being a switching supply; that's pretty much a given. I meant the external supply.
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Old 10th May 2008, 07:39 PM   #8
shagone is offline shagone  United States
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my bench supply is a nice B&K 25 amp conventional power supply not a smps. it has seperate 2 amp tie points that i run the head unit from. i have a spare 13.8 volt 20 amp ham radio supply that i'll hook the head unit to and try.
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Old 10th May 2008, 08:03 PM   #9
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How much current is it pulling through the resistor?
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Old 10th May 2008, 08:09 PM   #10
shagone is offline shagone  United States
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Quote:
Originally posted by Perry Babin
How much current is it pulling through the resistor?

good question? i'll check on that. i don't remember it being very high though.
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