My '88 300 SEL has the original Becker audio sytem installed. I currently have no sound from my left speakers. I have trouble shot the issue to a bad l/h amp that resides behind the upright back seat cushion.

From searching this appears to be a common failure item in this system.

I have found a couple of replacement amps from a 1990 300SEL salvage vehicle. My issue is that the amps I pulled from from the vehicle have a different P/N.

The P/N installed in my vehicle is 126 820 1489. The P/N from the pulled units is 126 820 1889. The 1889 P/N also has an external ground lug where the 1489 does not.

Provided I have a good unit, will the 126 820 1889 amp work as a plug and play unit for my vehicle?

Thanks

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BENZSTER

W123, '81 240D, Pastel Grey/Blue Tex
W126, '88 300 SEL, Artic White/Grey Leather

Despite the Spam, as I recall the W126 amps are the same from the interior update until the end of the W126. I know 90 to 91 are the same at least, my car has one '90 amp in it.

-J

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

I might be mistaken but the Becker Europa "MU" came in 2 sizes...Best is to measure the HU you have and for the single DIN(180 x 50 mm - depth is not standardized). DIN Automobile Radio Specifications ---- Deutsches Institut für Normung e.V
- German Institute for Standardization was adopted as a global standard in late 84.

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Are you sure it isn't a corrosion problem on the pin or amp female connector?

No obvious corrosion was noticed on any of the electrical contacts.

I temporarily plugged in the 1889 amp in place of a 1489 and it seems to work just fine on the r/h channel. The 1889 did not work to resolve my problem for the l/h side speakers. The original suspected non-working 1489 amp is now back in the l/h position.

I still can't get sound from the l/h speakers with the radio but, I have discovered that they all work just fine with the cassette player...

I did get sound from the l/h side speakers with the radio when I swapped the original 1489 amp from the r/h side to the l/h side when trouble shooting my problem.

I find it odd that the l/h and r/h speakers all work normally with the cassette player but not with the radio.

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BENZSTER

W123, '81 240D, Pastel Grey/Blue Tex
W126, '88 300 SEL, Artic White/Grey Leather

What you say about the tape player working on both L&R speakers but not the rest of the system seems impossible. The rear tuner is still needed and those wires from the tuner go out to the L&R side amps so that would be impossible for both sides to work. Are you sure?

Yep, I know it sounds goofy. I couldn't believe it either. I went one step further and disconnected the r/h amp and cranked up the volume in radio mode. There is some extremely faint audio coming through on the l/h side. Perhaps an issue within the head unit? Just a guess at this point.

On the brighter side of things, I'm getting reacquainted with some long forgotten vintage cassette tunes...

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BENZSTER

W123, '81 240D, Pastel Grey/Blue Tex
W126, '88 300 SEL, Artic White/Grey Leather

Now with cooler temps in my area, the audio system is working normally. I'm pretty sure the original fault is going to come back when temps warm up.

At least for now, I can give the old tape player a rest...

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BENZSTER

W123, '81 240D, Pastel Grey/Blue Tex
W126, '88 300 SEL, Artic White/Grey Leather