Noob here with a question regarding a bad preout

[goondawg]

I bought an Alpine 103bt from Crutchfield and it seems the right front preout is bad. The front left works fine but there is no sound coming from the right front. When I switch the the plugs around the left doesn't work but right starts working. So, it seems the amp is working fine but the right front preout on the HU is not sending a signal. Am I missing something or does it seem to you the right front is bad?

Apologies if my terminology is not right or I didn't explain myself properly. Thanks in advance with any help

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[sacsking916 5,000+ posts]

try new rcas?

 

[keep_hope_alive Premium Member]

good first test. yes, the amp is good.

to diagnose if the RCA is bad you can do two things (this assumes amp is good which is verified once the problem changes sides):

1. use a DMM to measure resistance. you're looking for continuity (low resistance) on the center pins of the RCA (one lead on each end). additionally, you're looking for an open circuit (high resistance) between the center pin and shield (measured on one end). commonly, there is a short between center pin and shield - which prevents the RCA from working.

2. swap the RCA's at the head unit, note the change (if any). swap the RCA's at the amp, note the change (if any)

HU Swap only:

problem changes sides - HU output is bad.

problem stays the same - RCA is bad

Amp Swap only:

problem changes sides - HU output is bad or RCA is bad. Indeterminate.

problem stays the same - Amp is bad

HU and Amp Swap:

problem changes sides - RCA is bad.

problem stays the same - HU output is bad

 

[keep_hope_alive Premium Member]

I made you a picture

 

[goondawg]

Thanks for all the advice. It really helped a lot