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Rockford Fosgate T400-4 audio problems
Rockford Fosgate T400-4 audio problems
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Old 30th March 2018, 09:13 PM   #1
rhempz01 is offline rhempz01  United States
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Default Rockford Fosgate T400-4 audio problems

Audio has a very bad ground like noise. The front left seems to be the worst channel. It actually clipped when I attempted to listen to that channel. Not in protection no shorts in any fets in curcuit. When I touch u3 it is noticable though the output.
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Old 30th March 2018, 09:20 PM   #2
rhempz01 is offline rhempz01  United States
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R111 in pre amp section is open a 50k 1% 0805 resistor.
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Old 31st March 2018, 06:04 PM   #3
seankane is offline seankane  United States
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This fixed the amp?
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Old 31st March 2018, 06:23 PM   #4
rhempz01 is offline rhempz01  United States
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No sean just what I found I don't have that resistor. Maybe something close but I don't have a 50k
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Old 1st April 2018, 04:12 PM   #5
seankane is offline seankane  United States
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Ah OK gotcha!!
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Old 1st April 2018, 04:38 PM   #6
rhempz01 is offline rhempz01  United States
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I can't find a 50k in the dozen or so amps I can't fix either so I order some with the parts to some other amps.
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Old 1st April 2018, 04:39 PM   #7
rhempz01 is offline rhempz01  United States
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It acts strange I have had these amps have bad output that we're not shorted but cause audio distortion. Strange.
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Old 20th April 2018, 09:55 PM   #8
rhempz01 is offline rhempz01  United States
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I just got two more prime amps with no shorted mosfets, or outputs just no audio?
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Old 23rd April 2018, 04:18 AM   #9
seankane is offline seankane  United States
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Have you checked supply voltage to your op-amps and such? All regulators are working?
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