CM5908 Stereo unit crackling and popping issues

[Amero6297]

I want to troubleshoot the CM5908 Alpine unit and see what the failure in it was. It does turn on and operate normally but had an awful cracking and popping sound coming from the front right speaker and sometimes other speakers too mostly which used to only happen after long trips but now is random and can happen instantly. The speakers are stock. When I disconnect only the front right speaker only it would then transfer the static over to the rear right or rear left or even the left front or some combination so I know the unit is causing problems here. Disconnecting all and only leaving the front left speaker connected had no more issues with popping and crackles so the unit definitely doesn't have enough power to run all four stock speakers so I autopsied it and went straight for the capacitors attached to the PCB board where the cables connect too. Its hard to say but i think they capacitors look fairly healthy? One thing I noticed however is that some of them have this weird zebra like pattern on the sides and some don't - see the second and third picture. Could anything else be causing problems before I start removing all these?
I have already upgraded to the Continental radio TR7412 along with some nice kicker's. But I have spare time to fix the cm5908 and want to get it working normally again.
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[m60power]

This happens with age on the stock alpine and pioneer radios. I've had the same issue on some of my old radios in my e34 and e32s; from what I remember the problem is actually with the volume knob itself. I had one of my good condition e32 radios rebuilt by a guy in Florida (I'd have to look up his contact info) mainly to fix the tape deck, but he also did the repair for the volume knob / crackling, and it works perfectly now. I see you are in Australia so he might not be the best option with shipping cost and whatnot... Anyway, I'm pretty sure this problem is usually just the volume potentiometer of the radio.

Edit: re-reading you post, you mention the crackling doesn't happen on the left front channel? I guess it's also possible that there is an issue with the amplifier in the trunk?

[Amero6297]

Hi, sorry for late response. Yes it never (or rarely) ever happened on front left. like i said disconnecting all speakers except the front left kick panel the speaker would operate as normal. I can't remember half a year ago but i think if I only left one of any of the 4 channels connected it will not pop. This is why i assume maybe some parts inside the stereo have failed like the capacitors since they usually are the first sign when something doesn't work to full potential like the instrument cluster's case. Also, My car didn't come with an amp. It runs off the unit itself. Its the most base model of the E32 you can get so no extra's what so ever. Appreciate ya.

[negativebias]

This happens with age on the stock alpine and pioneer radios. I've had the same issue on some of my old radios in my e34 and e32s; from what I remember the problem is actually with the volume knob itself. I had one of my good condition e32 radios rebuilt by a guy in Florida (I'd have to look up his contact info) mainly to fix the tape deck, but he also did the repair for the volume knob / crackling, and it works perfectly now. I see you are in Australia so he might not be the best option with shipping cost and whatnot... Anyway, I'm pretty sure this problem is usually just the volume potentiometer of the radio.

Edit: re-reading you post, you mention the crackling doesn't happen on the left front channel? I guess it's also possible that there is an issue with the amplifier in the trunk?

Who repaired your radio?

[m60power]

Who repaired your radio?

Bill Henn
radiodoc@bellsouth.net
Saint Augustine, FL

I don't think he has a website. I emailed him directly. His service was fantastic.

[negativebias]

Bill Henn
radiodoc@bellsouth.net
Saint Augustine, FL

I don't think he has a website. I emailed him directly. His service was fantastic.

Thank you so much!!