noise issue on rockford rfx 8140

[Perry Babin]

babin_perry@yahoo.com

 

[steveo3002]

ok

i resoldered the bad looking joints , checked all over for burnt tracks or components , and soldered on 2 bridge wires that perry emailed a link to

its pretty much the same , maybe a tad better but its probably wishfull thinking

 

[Perry Babin]

To do any further troubleshooting, you'll likely need a signal tracer. If you were in the US, I'd recommend the Radio Shack mini-amplifier but I doubt it's available there. Maybe you can find something similar.

 

[steveo3002]

edit..

found one cheap in uk ebay

if i get one , is it likley that i will fix it ? i dont want to spend $$ on equipment then be unable to fix it anyway , if you dont mind maybe a quick outline of what the next step will involve please

thanks again

 

[Perry Babin]

The mini amp would be used to listen to the signals on the input and output pins of several components (ICs, transistors...) to see if you can find the point where the noise is entering the audio chain. If the problem is internal to the head unit, it's possible that the mini-amp will help track it down but there are no guarantees.

 

[steveo3002]

ok i'll get it ordered then..will report back when its in my hands

 

[steveo3002]

ok i have the radio shack amp/speaker here now

next step in dummy terms please

 

[Perry Babin]

Power up the head unit in the vehicle (assuming that the noise was being produced by the charging system in the vehicle) and connect the mini-amp to each channel to confirm that the same channel is noisy with the mini-amp as with the original amplifier.

 

[steveo3002]

ok i'll do it...i know its not the charging system

as mentioned before i ran it in the house with a spare car battery and my home hifi amp

 

[Perry Babin]

If it's not related to the charging system, you can test wherever it's most convenient.

 

[steveo3002]

ok its still making the noise , most apparant at low head unit volumes

im getting it on the right too with this set up...maybe a tad less on the right side

 

[Perry Babin]

Does the noise appear to be ~400Hz?

 

[steveo3002]

no , lower than that and not a constant tone

sorry i dont have a way to record it (let me see if i can figure something out)

id describe it as a fluttery sound

 

[Perry Babin]

Do you have a non-polarized capacitor of approximately 1uF?

What is the resistance from pin 4 of U8 or U9 to the case of the head unit (no power applied)?

 

[weesatron]

I have an old alpine cd player from the 80s that would do the same thing. Problem i had was my battery was only holding 10 volts. Might be worth checking your battery voltage with the key on but without the engine running.