jimwyn2

When I turn the radio on in my C4, I immediately get a loud buzz/hum like I'm getting feedback. Did a recon on the radio and replaced the amp in the driver's side. What should I be looking for that could cause this hum??

RICHARD TILL

What model and radio is in the vehicle?

jimwyn2

It is the factory original Bose system for a '93 Vette

billschroeder5842

Your EDM may be going out. It is a common problem and a PITA to fix. I replace my EDM and all four amps on my 91. Now the system is good as new.

jimwyn2

Are there any other possibilities? How would I troubleshoot to know for sure that is the problem?

billschroeder5842

Not many other possibilities as it is a pretty simple system; head unit to EDM to Amp/speakers.

I understand your wanting a different solution but 99% of the time the EDM on these cars go kaput.

The only thing you can do is try swapping your amp with a known working amp. If you speaker works then the EDM is good and your amps are bad.

jimwyn2

I guess E Bay is my next stop. Thanks!

aklim

Maybe you need to but ask yourself this. How important is it to you that you have THIS unit working? If you don't care about the radio, leave it alone. If you want a better unit, shell out a few bucks to have some guy break his back for you crawling around there and laying wire for the speakers. That is what I did with Best Buy. I made sure they left a foot on each end extra so I can go home and do the wiring myself. They are young, let them do the back breaking work. You do the soldering part.

Final option is to get someone like Dr Don to fix the parts for you. I don't know him personally so hard to say but others have said he is good. I just dumped the Bose into the trash can and added my own stereo with the modern amenities. Bought brackets for non-Bose and put other speakers in place and it all buttons up nice and neat.

Best part of all is that now I can change the speakers or head unit at whim and not be married to the outdated Bose crap. Yes, it was great at one time but not anymore. Fixing it costs money and makes me have to keep everything Bose. Now that it is gone, no more. I can change the fronts or backs or both and the head unit at will.

pcolt94

Is it out of all 4 speakers or just one ?

If its all 4, it might be the CDM and I might have a fix for that. (I just did an inexpensive repair on mine)

Got any electronic and soldering experience ?

Baddabing

I had the same problem.... Speakers/amp. dead....

Installed new speakers/HU after that...

aklim

Slightly used CDM for sale

Baddabing

good price - only used for 28 years....

The new Poineer HU....

aklim

Why throw good money away trying to keep something alive which hamstrings you in choices when there is much better

Silver85

I ask myself this question every time I spend money on my C4. Not sure why but I keep doing it.....😁

aklim

Pretty simple for me. Spent too much money with upgrades and we don't throw away our toys just because something new and shiny comes along. Play till it is broke then I get to buy a new toy. Rules or we will simply buy things, throw them away when the next color comes along.

jimwyn2

Replaced the CDM and right rear speaker unit. Still get the loud hum out of right rear speaker. Just had the head unit reworked a couple years age.

pcolt94

Did the parts come from a private person or a company?
Do you have any assurance that the parts were checked out or working?

You can always swap the left speaker box over to the right and see what the result is. If it still hums it's (probably) not the speaker box.

Other than the hum, is there any audio or sound that comes out of any speakers?

Can I make the assumption that the radio was working normal at one time and then the problem developed? That would indicate the wiring is OK probably.

You should change one thing at a time or you don’t have a base line or reference as to what is good or bad. More than likely only one item is bad however with new items brought into the picture it makes for more variables.

billschroeder5842

If the other three speakers sound fine, you need to change the AMP on the right rear, not the speaker

pcolt94

The OP said he changed the speaker unit.....not the speaker.
I take that as the whole speaker box with the AMP in it.

jimwyn2

Problem solved! Thanks1