OEM radio has power, no sound...

[91bmw525i]

Hi all,

This is my first post so don't mind my disclosure...
A few problems have popped up with my '91 525i so hours of searching about how to resolve the issues on the internet have brought me to this informative E34 community!

After searching these forums I still haven't found what coule be the issue with one problem I'm having with the oem radio. It powers on, I can operate all of its buttons, change radio stations, sound settings, etc. But the problem is there is no sound coming from the speakers.
At random times for a few seconds at a time I am able to hear music though. Sometimes it is preceded and/or followed by some cracking or popping. At first I was thinking that the speakers may need to be replaced, but when I am able to hear music it sounds perfectly fine.
Damaged/popped speakers wouldn't be able to produce normal sounding audio right?
What could be the problem?
I checked the fuse in the oem amp and it is fine. Are there any other fuses I need to check? Could it still be the speakers? Are there any common known areas where bad connections could cause this?

All help is appreciated!

EDIT: pictures of head unit and amp on page 2

[Interceptor]

What could be the problem?
I checked the fuse in the oem amp and it is fine. Are there any other fuses I need to check? Could it still be the speakers? Are there any common known areas where bad connections could cause this?

Did you check the wiring? Maybe the audio connection to the radio is lousy/corroded/oxidated? Try taking out the radio and clean all the connectors/contacts on the back.

[Robin-535im]

With the radio off, turn the volume knob back and forth all the way 249 times. Or 248... I forget...

You can get dirt in the rheostat and lose contact, but turning it all the way up and down a lot will clean it out.

Worth a try before you pull it out.

- Robin

[Elekta]

You can also wiggle the wires coming from the amp under the back seat. I've done this with the radio on and discovered loose connections to some speakers.

With the engine off and key out, pull off volume knob and spray contact cleaner all around inside. Then do your 248 turns with everything off and see what happens.

Sadly, more than likely an amp in the head unit is gone. From roundel, there is a repair company out of Florida that rebuilds your head unit

www.soundrepair.com

I bought another one on tha bay and it cured everything, so I am going to send my fritzed one to these guys to have a backup.

HTH

geoff

[spddmn713]

I had an aftermarket amp in my last car and the same thing happened - unfortunately the problem was that the circuit board on the amp - I did not try to fix it I had a warranty and just exchanged it. The guy that I bought it from is a family friend who managed a car audio place told me it was the circuit board on the amp. I hope that it is something as simple as trash in a connection or some kind of other simple fix for you.

[91bmw525i]

Well, I pulled the radio out and checked the 17 pin connector in the back. I took a q-tip and cleaned the connectors and receptors... still no sound. They were a bit dirty though.
I also tried the volume knob back-forth turning, but i lost count somewhere around 150 I'll keep trying that again later though. Another problem I'm having with the car is the cd changer, the fuse was burnt out on that so I'll pick up some contact cleaner for the knob while I'm out for the fuse.
Are early 90s bmw oem radios known to "die" like this due to internal problems? Such as the circuit board or amp in the headunit as mentioned above? The stock radio in this car was never "blasted" or played at loud volumes...

[shogun]

Just had a prob this summer, as we have very high humidity in the raining season (+ 95% humidity). It just got stuck and I could not change anything.
Removed the radio, brought it to the Sony headquarters here in Tokyo, which is right around the corner where I live. They could not find anything wrong.
Put it for some days in my fridge to get the moist out and it works again. Also dried it with a hair dryer.

Moisture is a big prob for the connections.

Here are the PIN connections

click

[Javier]

are we talking about?.

I have a Babaria C Professional RDS (1992) and it is working fine. Some time ago I got issues with some speakers muting, and found poor contact inside the trunk amplifier/tuner unit (Becker brand). There is a motherboard inside with some boards connected to it; the connector is like some tiny gold plated wires, going into small holes in the motherboard. In one of the boards, the connections were causing the problem, as I kept the system operating, and when shaking that board, noticed the speaker going on and off. May be you’re having something similar. Some contact cleaner, and even a small soldering point can fix it.

Javier

[91bmw525i]

Thank you all for your advice so far. The radio is still not working. I pulled the amp again today in order to open her up and see if anything is going on inside, but I found that the screws holding the cover are ones I have no tool to remove them with, (darn torx/hex, whatever they are).

I also replaced the burnt fuse of the cd changer, it seems to be operating fine. The disc holder pops out but the oem radio doesn't seem to be recognizing it. I press the "Band" button and it only switches from FM to AM, the cd option isn't available...

This problem is really becoming aggravating...

(The stereo is the in dash cassette player with cd changer. Not sure of specific name though. It's in a US model 91 bmw 525i)

[danzee]

I agree that the most likely cause is a bad connection - either wire, connector, or on a board. Now try to work through it in logical sequence. You have a good start by having eliminated the connector at the radio as a problem. I would suggest that next you look at the line outputs from the radio to the amp. That is look at the amp input(s). Whether you just jury rig a pair of high impedance headphones or use the input of a stereo amp or boom box. If you can hear consistent sound there, then you know it's good up to the amp. If you have a friend with some electronics smarts, maybe he can help. You can also try the check out the path from the amp through the speakers by "injecting" a signal from another source (MP3 player, etc) at the amp.
I don't know if a radio from a 1991 318is can help you, but I have a spare one if it comes to that. Just ask.
Dan Z