Silence...... (Becker 1432 lost all sound)

[Bahnstormer]

Hoping that someone might have an idea of what's wrong with my 1432. I did some searching but didn't find anything.

When I pulled my 93 500e out of long term storage, I got the E2 code after entering the security code. After some research I learned that the tuner in the trunk was likely toast so I bought a replacement on ebay from what seems like a reputable seller. I thought I'd try the cheap route and also have something working while I send my original tuner off to Becker for repair.

It arrive quickly and I installed it a couple of days later. To my surprise the 1432 came to life and all functions seemed to work well. After 30 minutes of driving however I lost all sound - crickets.... The head unit still seems to perform all functions but no sound??

Checked all the tuner / 2 amp connections and all are good.

Does anyone have previous experience / potential fix?

Thanks!

 

[niz93]

your system only tuner in the trunk or tuner + 2 amplifier?

 

[gsxr]

USA 500E's all have 2 amplifiers in trunk (Sound System option), and the 1432 has the tuner in the trunk as well.

 

[niz93]

check sound on connector amplifier in tuner, DIN 41529, after this check, it will be clear whether the problem is in the tuner or in the amplifiers

 

[Bahnstormer]

check sound on connector amplifier in tuner, DIN 41529, after this check, it will be clear whether the problem is in the tuner or in the amplifiers

Thank you - but I do not see that type of DIN connector on either of the amps??

 

[sheward]

Have you tried rotating the fader (front to rear) on the console? These are known to get crusty from corrosion and non use.

 

[gsxr]

Thank you - but I do not see that type of DIN connector on either of the amps??

DIN connector is between the head unit and the tuner. The amps are separate.

 

[Jlaa]

Hello @Bahnstormer - I believe you are trying to isolate the problem to either:

1) The amplifier
2) Or the tuner module

Unbeknownst to most people with w124 stereo knowledge, (because "professional" stereo shops of the day largely had experience with pedestrian 124s and not "sound-system" equipped v8 124s) The 036 w124 has line-level outputs, before the fader, on the tuner module, which can easily be tested.

Your tuner module should look like this on the back:



Do you see that modular line-out module? You can actually take that off and plug it into another tuner module! Anyways, that line out module feeds the fader knob, which then feeds *back* to the amplifiers. If I were you, what I would do, in order, is:

1) Try rolling the fader wheel front and back and front and front and back and front and back a whole bunch of times first. If the fader wheel has corrosion from humidity in the air, then the line level signal won't get to the amplifiers, which results in no sound. As well, if the fader knob is disconnected because you took apart the center console, there won't be any sound either. I know this because I was a dumbkopf and did this and it took me 30 minutes to realize the error of my ways.


2) Try to see if you have a signal coming out of those three pins on the tuner module. Maybe the problem is as simple as the line-out module is loose. Anyways, on my car, it looks like this:



Those three pins should have, from the diagram below,

LEFT POSITIVE LINE LEVEL - Blue
RIGHT POSITIVE LINE LEVEL - Red
COMMON GROUND FOR BOTH LEFT AND RIGHT - White or Yellow


You could test with a spare amp (feed the amp with those pins) or perhaps attach an oscilloscope to them and see if threre's a signal coming out. A spare amp lying around w some speakers is probably easier than an oscilloscope. Final note - I would find it hard to believe if both amps, L and R, failed at exactly the same time. Good luck and let us know.

 

[Jlaa]

@Bahnstormer By the way, when @niz93 talks about DIN 41529, he might be talking about these.
I'm not really sure --- I have never seen these used in US market 036 cars, and niz resides out of the US. Niz is certainly a very accomplished technician / lots of experience with electrical engineering though.

 

[Jlaa]

Just to be a pedant --- I believe @niz93 is talking about the "active bass" set up, instead of the US "sound system" set up found in the US v8 w124 cars. Note that an "active bass" set up will not have the line-out module:

• Active Bass (pedestrian US market w124s and also what I believe @niz93 to be talking about)
  • Tuner/Amp Module in the trunk - this powered the 2 dash and 2 rear-deck speakers, full range.
  • 1 Active-Bass amplifier in the trunk - this powered the 2 front door speakers --- low frequencies only!
  • The Fader wheel was AFTER the tuner/amp module but since the built-in-amp in the tuner/amp module was used to power speakers, the fader wheel was at speaker-level (and not line-level)
• Sound System (US market v8 w124s)
  • Tuner/Amp Module (I think the same one) in the trunk with a line-out module bolted to the back.
  • 2 amplifiers in the trunk. One amplifier powered the left-side dash/door/rear-deck speakers, and one amplifier powered the right-side dash/door/rear-deck speakers
  • The fader wheel was also after the tuner/amp module, but since the tuner/amp module wasn't being used to power any speakers, the fader wheel was at line-level.

Anyways I confirmed that the line-out module can be easily detached. See here:

 

[niz93]

in euro this connector main speaker out)

be1432 has an identical board design and has amplifiers on board for autonomous operation without additional two amplifiers

if the problem is inside the tuner, there will be no sound on these outputs, if there is sound on them, the problem is lower, most likely directly in the additional amplifiers

 

[Bahnstormer]

Hello @Bahnstormer - I believe you are trying to isolate the problem to either:

1) The amplifier
2) Or the tuner module

Unbeknownst to most people with w124 stereo knowledge, (because "professional" stereo shops of the day largely had experience with pedestrian 124s and not "sound-system" equipped v8 124s) The 036 w124 has line-level outputs, before the fader, on the tuner module, which can easily be tested.

Your tuner module should look like this on the back:

View attachment 196893

Do you see that modular line-out module? You can actually take that off and plug it into another tuner module! Anyways, that line out module feeds the fader knob, which then feeds *back* to the amplifiers. If I were you, what I would do, in order, is:

1) Try rolling the fader wheel front and back and front and front and back and front and back a whole bunch of times first. If the fader wheel has corrosion from humidity in the air, then the line level signal won't get to the amplifiers, which results in no sound. As well, if the fader knob is disconnected because you took apart the center console, there won't be any sound either. I know this because I was a dumbkopf and did this and it took me 30 minutes to realize the error of my ways.


2) Try to see if you have a signal coming out of those three pins on the tuner module. Maybe the problem is as simple as the line-out module is loose. Anyways, on my car, it looks like this:

View attachment 196894

Those three pins should have, from the diagram below,

LEFT POSITIVE LINE LEVEL - Blue
RIGHT POSITIVE LINE LEVEL - Red
COMMON GROUND FOR BOTH LEFT AND RIGHT - White or Yellow
View attachment 196895

You could test with a spare amp (feed the amp with those pins) or perhaps attach an oscilloscope to them and see if threre's a signal coming out. A spare amp lying around w some speakers is probably easier than an oscilloscope. Final note - I would find it hard to believe if both amps, L and R, failed at exactly the same time. Good luck and let us know.

J - thank you so much for taking the time to provide such a detailed response. I'm far from even being an electronics/wiring novice - but I'll re-check the line out connector.

After @sheward suggested fiddling with the fader, I rocked the wheel back and forth several times while the 1432 was on - I could hear some faint pulsing sound from the front speakers but nothing when rotating the wheel to the rears.