Mercedes Benz Original Becker Stereo Radio Fix on R129 and Others

[@douglasthompson9482]

I purchased a new head unit....a Sony, though not my first choice, the best that I could get presently. The installers bypassed the entire stock amplifier . Fabulous music that looks great too. I did keep the original unit though incase of resale. Now I have all the modern day capabilities....wow.

[@HandyVal]

A modern unit, like the Sony, has many benefits notably the extra connectivity features with our phones, improved display and ease of use. I find the Becker isn’t the easiest to navigate. However, the Becker does have a cool retro look. Replacing the Becker components when they’re not working can be costly. My AM FM radio tuner recently stopped working (I made a KZbin video on it too). A new unit can be more cost effective. Maintaining the Becker can be expensive.

[@brianfrew9556]

Hey Doug I'm curious if you changed out all the speakers with the sony head unit? If so what did you do? I'm looking to modernize my SL. Cheers

[@johnfloore9799]

Hey Val, I have a 93 400SEL that had a Becker 1432 in it when I bought it. But it had a very different speaker set up, as it had the Bose system with a 7 channel amp in the trunk. This dual amplifier set up that you have reminds me of the system that came in my other Mercedes, a 1989 420 SEL. In that car, there were 2 small amplifiers, just like the one shown in your video behind the back seat. Regardless, in both cars I had a problem with high pitched buzzing (like alternator feedback.) What I finally ended up doing was replacing the head units with Continental head units that look quite period appropriate. In the 126, I rewired the whole thing with new speakers plus a sub and a 5 channel amp from JL audio. But for the w140, I just went with a rebuilt amplifier and a "plug and play" kit from becker auto sound that included the Continental headunit and wires to interface with the factory amplifier. Needless to say: the second option was cheaper and easier, and to my ears sounds just as good.

[@HandyVal]

Thanks John for sharing your experience. The Continental headunit looks and feels like it was made for these 90s Mercedes. It looks like original equipment but without the Becker quirks. If my headunit goes bust, I'll likely go in that direction.

[@wernervanhalewyck9265]

I have a similar problem with my bass speaker...but it mainly occurs on the passenger side. I was about to look for another set of original speakers. I hadn't thought about the bass amp. So thanks for this video. Honestly? I didn't know that separate bass amp was housed under the passenger's feet. Maybe I should check there first and look for a replacement. I find your videos very instructive, well and clearly made. Like you, I try to keep the original specifications of my R129 as much as possible. So yes , also amber colored winkers , the Becker stereo .Best regards from Belgium.

[@HandyVal]

Werner. Bedankt, merci, and danke. Thank you. I appreciate your feedback. I agree, you should start with the bass amplifier. You can try tapping on the bass amplifier and seeing if it makes a difference. If it does, then you certainly found your problem. It can also be a loose connection. If it was always the passenger side then likely it would be the speaker, but because it sometimes occurs on the driver side, it’s likely not the speakers, unless they are both water damaged…it’s possible. You can also try unplugging the connectors on the head unit and then replugging them. Speakers can also be repaired quite easily by any speaker shop. Keep us informed.

[@wernervanhalewyck9265]

@@HandyVal Thanks Val, I'll check it that way…. What you have already diagnosed correctly are the three official languages ​​here in Belgium , bedankt ( dutch) , Merci ( French) and Danke ( German) 😉

[@rioraton]

Yep, had the same problem! 1st time I had a short in the bass unit and it was draining my battery took me months to figure out. The only way was for me to sent all 3 pieces to Becker North America in New Jersey and they found it and rebuilt the base. Got it back worked great and failed again. Sent it back to Becker and they replaced the amp... even their fix did not work for long.

[@HandyVal]

It’s a crazy complicated system that I wish the MB engineers made a bit more simple. I’ve heard great feedback from those who used the Becker shop in NJ.

[@rioraton]

@@HandyVal Yes, those dudes are GREAT and very professional AND reasonably priced too

[@johnmcdonald9831]

Brilliant as usual. Happy New year and many thanks 😊

[@HandyVal]

John - Thanks and Happy New Year! Let's hope for a great 2022. I checked your weather forecast and it's almost roof down weather 😃

[@billrbca]

thanks for the video, dealing with my '90 with a 1480 becker head unit, wow thought the amp was more up under dash, really easy, wonder why there are relays in that, I may send to Becker in NJ for rebuild/repair whatever. Will clean as shown out of curiosity.

[@HandyVal]

Thank you. Those relays are meant to protect those bass speakers upon start up where there can be excess power. Which isn’t really necessary - a few I know have bypassed the relay (requires soldering) without problems. Try the electronic contact spray, you may have a better experience than me. Further, I’ve only heard very good things about Becker NJ. Either way, let me know….

[@billrbca]

@@HandyVal I am going to send my head unit for a 'refresh' and bluetooth install, will update you on results

[@rafaelcardoso6252]

love your videos val! where do you get that dasboard toolkit?

[@HandyVal]

Thank you! The kit is from Amazon - look up - auto trim removal kit. The one I have looks like the Juning brand. They are all similar, but when buying make sure it has the stereo removal keys. The whole set should cost in the range of $20 to $30 USD. They are mostly made by the same manufacturer but use different names.

[@rafaelcardoso6252]

@@HandyVal thanks. I found a 148 pcs manfiter that seems identical. Thanks

[@r129channel]

Hi Val. Great video as always. No comment on the Becker or the amplifier but I noticed you mentioned the three speakers on each side. I've been seeing some conflicting reports about the speakers up on the dash right above the left and right air vents. Some say in the US it is a speaker for the optional integrated phone. Even if the car wasn't optioned with the car phone, the speaker would still be there. But others have said that those speakers are indeed for the stereo system. I assume the older R129s are going to be different than the late model ones but wondering if you have more info to share about those little speakers. I have a '94 R129 and I swear there's stereo sound coming out of those little speakers.

[@HandyVal]

Thanks for the great feedback. My 92 SL, which isn't equipped with the integrated phone, clearly has sound coming from those little dash speakers (tweeters). It's the very high frequency sound and they (tweeters) are necessary equipment for any audio system. I think all R129 dash speakers worked with the stereo. But I believe for later models they served dual purposes - for stereo and for handsfree calling, where equipped. The microphone was located near the rear mirror\map lights. I don't know when this dual use started, certainly in the 2000s, but 90s - unsure.

[@Carduelis_parvaksa]

Thank"s 🙂

[@jameslaidler2152]

I see why you didn't want to try your hand at soldering on this thing, though others might be willing to give it a go. Going to guess you don't locally know anyone electronically inclined in that regard? Smart decision regarding the relay cover though. Would Focal speakers fit in those doors? Really nice French stuff. You could match the Ohms by using audio quality resistors in parallel to get the resistance to match. Just hope the stereo has individual volume controls for the three speakers.

[@HandyVal]

You make a good point about a local shop. It's certainly easier, if you know of a local electronic shop. I worry about getting fleeced. They likely might have been able to fix the issue. However, I do think Ebay is a decent option, but like everything it all depends on price. Focal speakers are great. I don't know if you can make them fit, it's a slim profile speaker that goes into these doors. Running parallel audio resistors - never heard of it, but that certainly changes everything and opens up many more speaker options, instead of replacing like for like. Thanks for your thoughts on the topic - great thoughts.

[@jameslaidler2152]

@@HandyVal It's not really difficult working on something like that. It's fairly small, and a set of schematics from a service manual would certainly help. It's not as scary taking components off and testing them as people may want to think. As for matching Ohms, Ohm's law works like this. Add resisters in series, it's a linear addition, 2+2=4 etc. Parallell works as division. For example, a 4 Ohm speaker, put a 4 Ohm resister in parallel with the speaker connections, it becomes 2 Ohms. Then add another 2 Ohm resistor to make 1 Ohm. The only issue would be matching volume levels between the drivers.

[@HandyVal]

@@jameslaidler2152 This is motivating me to roll up my sleeves and try to fix those non-working R129 stereo parts, like the bass amp and the Am/FM tuner. Many thanks.

[@jameslaidler2152]

@@HandyVal If you don't already have soldering supplies, you don't need to go crazy with it. Just do a little research and get a decent soldering iron, and you can stick with old fashioned 60/40, 63/37 lead/tim solder, just work in a well ventilated space, and watch as many videos on soldering as you can. As for resistors, just same decent sand cast resisters should do you, just like the white boxes already on the amp board. Just take your time and be patient.

[@Diamonds_Bulli_Ecke]

Hi Val, I have a Problem with my Mexico too. If I put a Tape in it and want to listen I get only mono sound with it. If I listing to the tuner radio channels I have stereo sound. Do you know the fault mate? Thanks!

[@HandyVal]

Hi Diamond. When the tape is engaged, you won’t see the stereo symbol (two overlapping circles) on the display but you’ll see the tape functions, either Dolby (DD B; DD C; or CR for chrome tapes) but you should be getting stereo sound, if the tape is original and recorded in stereo. If it doesn’t sound like stereo, it could be a dirty head, so you may want to try cleaning the tape head (either with a cassette cleaner product or with a Q-Tip soaked in cleaning compound - I think rubbing alcohol should work for cleaning). For the CD player, the stereo symbol should appear.

[@Diamonds_Bulli_Ecke]

@@HandyVal the tape is not original but recorded in stereo safe! If I touch the stereo button there won’t be a difference. It’s only mono with tapes

[@HandyVal]

Diamond. With the tapes, the unit’s LCD display won’t show the stereo indicator. It will only show the Dolby symbol or the CR symbol. So I think you’re getting stereo sound. If you don’t notice a difference between the left and right speakers, then I think it’s the tape head that needs a good cleaning. Bohemian Rhapsody by Queen is a good song to check left and right speakers. I hope I didn’t misunderstand you.

[@jamesreckling6697]

I have a 98 Sl500 so it has a different head unit. The problem I had was the LCD display went black. After searching for any solutions I determined the only way to go was buy a refurbished unit as I wanted the original look. Kinda curious if this model has a similar issue for people.

[@HandyVal]

@@jamesreckling6697 It is a common issue. My head unit has one similar fault. The LCD display works, but the orange backlight on the LCD display doesn't - it's likely burned. All other lights on the head unit work. I can see the LCD display during the day and partly at night. It can be fixed but requires the old backlight to be removed and replaced AND requires soldering. For your situation, I believe you will need to replace the LCD display unit with a new/used one (soldering I believe is also involved). You likely would struggle to find an LCD display. I would have, like you, replaced the whole head unit with a refurbished one, while still keeping the old one.

[@jasontoth7965]

Could you help me out and make a video on how you raise an r129 and exactly where you put the jack stands to have all 4 wheels off the ground?

[@HandyVal]

I’ve never jacked the car with all four wheels off the ground with 4 jack stands. It’s possible but risky. I’d be interested in a video too on a true, tested and tried process. 😃. I typically feel safer by keeping 2-3 of the tires on solid ground. I know it’s not the reply you were looking for. I’ll take this way and think about it more.

[@njoeandjen]

1991 300sl does anyone have a aftermarket diagram for stereo install the wire diagram thanks especially for wiring the midranges!

[@HandyVal]

I’ll check my files. I may have it. I’ll let you know if I do.

[@njoeandjen]

@@HandyVal thanks awesome 😎

[@HandyVal]

I don’t have a pure stereo only electrical wire diagrams but I do have the broader R129 electrical service manual and it does have a few references to the radio/stereo and speakers but likely not the detail you need. It’s a large pdf (600+ pages). You can contact me via email or Instagram or Facebook and I’ll can send it to you. My email: [e-mail]

[@douglasthompson9482]

Good video....my head unit keeps saying...wait. I have been waiting forever to put a code in. Yuk

[@HandyVal]

Thanks. Hopefully, you got the code in.

[@luisehenriquez4760]

You need to keep the head unit turned on with the Wait message until it says Code again. It can be hours depending on how many missed code attempts. If you need the code for your unit let me know.

[@id8205]

Error 3 code someone?

[@HandyVal]

The E2 and E3 codes are similar and typically mean some kind of loose connection and\or blown fuse. Fuses would be on the headunit (shown at the rear of the unit in this video), or on the Radio tuner ( kzbin.info/www/bejne/jJyrnGmng5asqsU ). I made a separate video link here for the tuner. To a lesser extent the fuse in the trunk fuse box (near the car's battery; it has a little slider cover) can cause a similar problem - check it out for corrosion. If badly corroded simply replace it. I hope these simple fixes are all that you need. Keep me updated.