4ch amp keeps cutting out then back on

1SlowSi

Junior Member
Let me describe my setup and how problems occurred. I was running an Alpine deck, JL 300/4 amp, and Polk 6501 front components, Alpine 6x9 rears. This setup ran for many months without issue but suddenly the JL 4ch amp started shutting off then back on ONLY at higher volumes. The other amp and sub stayed on during this shut off. I replaced the head unit and 4ch amp with new ones and it is still cutting out under high volumes. The amp shuts off for about 2 seconds then comes back on. Its very random when it turns off but its only at high volumes. Here is what I have done so far

-Test continuity for each speaker at the amp leads and also at the speaker. Everything checked out perfect

-Checked all my grounds/power and all is good

-Checked continuity to ground and nothing is grounding out

-Rewired all junction points to make sure all was clean

-Checked voltage at the battery and amp got 12-13 volts constant

-Traced all wires and inspected for pinches/cuts found none

-Tried all new RCA's, didnt work

-Ran the amp with fronts disconnected, rears disconnected and other variations of speakers that ran and no matter what it still cut out.

Now this is whats weird...

When I test the actual leads of the amp when its turned on, both left channels read -3.5 ohms and the right side channels read 4.5 ohms. I dont know if the negative ohm reading is normal or not but it doesnt seem right. When the amp is turned OFF, all the leads check out at 4-5 ohm positive. I cannot figure out for the life of me what this can be. ANY help would be greatly appreciated.

 
Aren't you suppose to check Ohm readings only when it is off? That would solve your Ohm problem, but the turning off and on is a issue. I have that same problem with my amp recently and haven't found a culprit yet. It happens at any time for a period of 15-20 seconds then turns back on. I'm trying to see a common occurrence (aka speedbump, pressing the accelerator, high volume, etc) with each cutoff and find a variable to test.

 
I only tested it with the amp on to get more info and see what the amp does. It doesnt seem right to me that while the amp is off I disconnect all the speaker wires from the amp then channels 1 and 3 read -3 ohms and channels 2 and 4 read 5 ohms. I would think that all channels would be equal in all readings. But again, this is a brand new amplifier and these were the readings within the first 24 hours i bought it. I highly doubt the amp is my problem but its just something else to question.

 
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1SlowSi

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