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 (http://ow.no/index.php?option=content&task=view&id=56&Itemid=43)

[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

[91bmw525i]

Thanks for posting Danzee, I had pulled the amp yesterday to see if the problem is there. But before I pull it apart I'd like to test your recommendation.
How would I go about testing the lines to the amp though? There are the two connectors, that connect to the amp in the trunk. I'm assuming one is coming from the head unit and the other out to the speakers. Does anyone have the wiring diagrams for these connectors?
Also, does anyone know if the 3 series and 5 series oem head units are interchangeable? If so then, Danzee I might just have to take you up on that offer.

[danzee]

I don't have the wiring info here. Maybe at home.
The radio (head) I have drives speakers directly. I'm not sure if it has provisions for the amp. I'll check this evening.

[Javier]

on the radio system. There should be a model identification in the Cassette door, or in the radio manuals, or in the card with the security code. May be posting pictures of head unit, CD changer and amplifier would help.

Javier

[91bmw525i]

My apologies for the lack of info.

Here are pictures of the head unit and amp in question;

http://img.photobucket.com/albums/v210/holla247/Misc/DSC02347.jpg

http://img.photobucket.com/albums/v210/holla247/Misc/DSC02353.jpg

http://img.photobucket.com/albums/v210/holla247/Misc/DSC02352.jpg

http://img.photobucket.com/albums/v210/holla247/Misc/DSC02350.jpg

[infinity5]

i had a similar sounding problem with my radio. same one as yours i believe. if you hold the mode and program button ( i think) at the same time it should display the radio maker and whatnot.


anyway, my sound would cut in and out with the volume, and if i tapped it would get really loud and relaly quiet. just like someone else suggested it might be a problem with the volume knob being dirty on the insides. i took my radio apart and took the volume knob out and soaded it in alchol and WD-40 and put it all back together and it worked perfectly :) go ahead and get a screw driver and go to work on it. twisting the knob several 100 times didn't work for me either, but cleaning it with something strong sure did. the insides are simple and everything clicks together with minniature looking IDE cables.

otherwise you might consider either a new headunit or a whole new system. the bmw factory amp and speakers leave something to be desired.

[Javier]

Sorry to tell you I do not recognize this unit (Nor have specific information for it). Per the description of the failure, I do not believe it may be a blown fuse, otherwise you wouldn’t be hearing “Sometimes”. Check fuses, though, not looking for a blown one, but for contact damage or even broken (not fused) filament. A continuity meter would help. For the Hi-Fi system to work properly, you need fully operative the F18 fuse in the front fuse box and F41 in the rear (under seat) fuse box, also the 6.3 A fuse in the radio and the 10A fuse in the amplifier.

As for wiring, I suppose you have a 10 component speaker system, if my info is correct, you have two 12 pins plugs in the amplifier, one white (X606) and one black (X605, pin 4 is unused). If so, this is the pin assignment for the incoming and outgoing signals at the amplifier:

Front Left input: X606-11

Front Right input: X606-6

Rear Left input: X606-12

Rear Right input: X606-5

Left common: X606-10

Right common: X606-4

Front Left High Range spkr: X605-1
Front Left Medium Range spkr: X606-7
Front Left Low range spkr: X606-1
Front Left spkr common: X606-2

Front Right High Range spkr: X605-8
Front Right Medium Range spkr: X605-6
Front Right Low range spkr: X605-12
Front Right spkr common: X605-5

Rear Left High Range spkr: X605-7
Rear Left Low range spkr: X606-8
Rear Left spkr common: X606-3

Rear Right High Range spkr: X605-9
Rear Right Low range spkr: X605-11
Rear Right spkr common: X605-10

I would check, with amplifier plugs unplugged, using a Vac meter, or a high impedance headphone, that there is incoming signal at X606-5/6/11/12 all referenced to ground (or X606-4/10). This will confirm there is signal arriving to the amplifier. You can also check continuity at each speaker, or connect a portable radio to the different speakers to confirm they are working OK (Doubt the problem is there. Continuity check would be easier).

I would also check for 12 Vdc at X605-2 to X605-3. Also check with radio on and off, the voltage to ground at X606-9, it should go up to 12 Vdc when radio is turned on. Check also that all connections are clean.

If all is OK, then I would open the amplifier looking for evidence of loose connections or damage.

Javier

[91bmw525i]

Infinity5; I tried the holding mode/program simultaneously but nothing happened. I found the part # for this radio in the manual, it is 88 88 1 600 245

Thank you Javier for the detailed instructions! But I do not have a continuity or vac meter. And I believe I have the 8 speaker system, two in the front dash, two door mounted tweeters, two by the kick panels by the front seats and two in the rear dash. Unless I overlooked two of them. =)

I checked fuses you mentioned but they were all fine.

I understand your instructions but how do I go about checking the pins w/o a vac or continuity meter using the headphones method? I don't think I have a set of high impedance headphones either. I looked up the specs for a set of headphones I could use and their impedance is 32 Ohm. Is that sufficient?

How much are the vac or continuity meters? Could I buy one at a radio shack? If they aren't too expensive I may just pick one up.

Thanks again javier and all. I have alot of leads so far, now i just have to check them all and hope the problem is solved with one of them.

[Javier]

A Multi-Meter is a handy tool for any electrical checks, not only at the car, but also at home, I think you need it, if you want to carry out this diagnose, as I told you, it is not only to check for not blown fuses that I'm sure you do not have, but for tricky things, the things that make an intermittent fault, poor connections, broken fuse links, and so. There are different prices depending on brand and functions, mine have AC/DC voltage and Amps, Resistance with continuity bell (Ohms), Capacitance, Frequency, and also some Diode and Transistor test functions. I paid about 110 USD about 12 years ago. I think it was a cheap one as the brand is not top (Beckman). You may probably find something better at a lesser price this days (Technology is a b..). Radio Shack is a possibility, check the web though, or get recommendations from someone from the forum living in USA.

If no meter at all, and you have a portable stereo system with a "Line In" RCA input and output to speakers, you may get creative and do some sound testing, but if no sound, you will not be able to check the presence of supply voltage at the amplifier, and, for example, at both terminals of every fuse.

The headphones will let you listen for signal at desired points, just use some extra bare wires to connect, 32 ohms is low impedance but you should hear something with them. At least it will let you discard problems in the head unit.

As for the speakers, you should have 2 components (H/L) below each screen at the rear side.

Javier

[91bmw525i]

I finally got a hold of a Fluke 77 multimeter. I've never used a multimeter before so excuse my ignorance. I jotted down notes of my findings. Not quite sure what to make of them though...

With the radio on and amp plugs unplugged I checked for incoming signal at X606-5/6/11/12. Putting the + probe on X606-5/6/11/12 and the - probe on X606-4.

With - on x606-4 and + on nothing = .002

- on x606-4 and + on x606-5 it fluctuated from .002 to its highest at .084

- on x606-4 and + on x606-6 it went from .002 and leveled at .06

- on x606-4 and + on x606-11 it went from .002 to .000

- on x606-4 and + on x606-12 it went from .003 to .001/.000


Then I tried the continuity check. The multimeter manual said if continuity exists it would beep continuously. The diagram in the manual shows to place the - on the "musical note" so I assumed the speaker. But I wasn't sure where to place the +. So according to the above list posted by Javier I placed the - on
Front Left High Range spkr: X605-1 (the beginning of the speaker list) and "probed" the pins with the + until I heard beeping, which was at x606-1. I then used x606-1 as the + point and tested each speaker.

Speakers x606-5, 6, 7, 8, 9, 10, 11, 12 and x606 -3, 8 did not beep.

Speakers x605-1 and x606-1, 2, 7, did beep.

(I'm not sure but I don't think I may have performed the continuity check correctly.)

Then I checked the Vdc at X605-2 to X605-3 and got 12.45 on the meter. So i guess that test is good.

Then with radio on and off, I checked the voltage to ground at X606-9. I wasn't sure where to place the - so I put in on x606-4 and the + on x606-9
With the radio on the meter showed .003
I then tried placing the - on a bolt connected to the body of the car and + on x606-9. The meter showed .039.

If Javier or someone could interpret these results I'd greatly appreciate it. I probably goofed up on using the multimeter, so if anyone notices I made a mistake with placing the + or - in my results and Javier's instructions above please let me know!

Thanks all!

[Javier]

For incoming signals, common is the point for the - probe for each group. (X606-11 and X606-12 to X606-10, and, X606-5 and X606-6 to X606-4). The read values should vary with the volume and the balance/fader adjustments. Should have some music running (high volume best) to get the reading. Per your results, I feel the head unit is OK (Left channels were not measured properly).

For speaker continuity test, again common is the place to put the - probe, and the + probe should go trough every speaker (for each of the four groups, - probe will be in X606-2, X605-5, X606-3 and X606-10). Per your results Front left speakers are OK, check the rest using their common as stated.

Please re-check with the radio on and off the voltage between X606-9 and X605-3 (X605-3 is same as ground or body, you can verify continuity from X606-3 to car body). Head unit should be connected, amplifier unplugged to have access to the X-606/X605 contacts.

You should have 12 Vdc between these points when the radio is turned on, this is the signal telling the amplifier to turn on. If no 12 VDC there, Amplifier doesn’t turn on.

Javier

[91bmw525i]

Thanks javier for pointing out my mistakes. I did the checks again.

x606-11 to x606-10 showed a fluctuating .001 to .003

x606-12 to x606-10 showed a fluctuating .003 to the highest .700 but then dropped down to fluctuate around .002

Continuity checks were good for all groups.

But the check for x606-9 to x605-3 only showed .025 vdc. I guess that's the problem then, the amp isn't getting power. =(

How do I go about fixing this problem? Does it mean there is a break in the wiring somewhere?

Thanks again Javier!

[Javier]

at pin X605-2, but the only way to prevent it to dry out the battery, is to turn it on only when the head unit is turned on, so X606-9 acts as a turn on signal. This is a white wire that also feeds power to the antenna amplifier.

I would check at the back of the head unit, at the 16 pin black connector (X18126), with the plug connected, that this white wire in position 16 is getting 12 Vdc when power is turned on. If there is the proper voltage, check continuity for this white wire to the amplifier end. A simple check you could perform is to connect power from X605-2 to X606-9. Amplifier should turn on and sound should reach the speakers. Be extremely careful of connecting the right terminals. It is the white wire the one that should receive 12 Vdc.

If head unit is not feeding 12Vdc when turned on to the white wire, you may want to check the head unit socket for corroded, bent or missing pin, or open it looking for a broken internal line feeding this 16 pin connection.

Javier

[pong]

from what im getting... there are 3 fuses that i have to look at...

one in the front...
one at the back... (where in particular)
and one in the general cabin area... (again where?)