I removed the Blauphunkt AM/FM/Tape deck in my latest 1983 300SD and installed a used Becker radio that is from the same era and style vehicle. I noticed during testing that the unit got quite hot on the side facing the driver. It was hot enough after maybe 10-15 minutes that I risked a burn if I touched it. Having nothing to compare it to as my other 300SD is in the paint shop, I'm not sure if this is normal or not. I know they get warm but how warm is the question. I also noticed that the LCD display is missing a character and after 20 minutes of driving, the left side audio channel cuts out. It is probably over heating and I need to find another unit. I have a 3rd Becker but guess where it is? Yep, Maaco, on the floor of the 300SD...

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1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

That's too hot for sure.

They have incandescent bulbs for illumination so they will get mildly warm but not hot.

Unless the sun is beating down on it?

I would send it off to Ed at Becker, chances are he can repair it. Not cheap (I would plan on $150 minimum) but worth it. Becker Autosound Website

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Well, to be clear, I reached under the radio where the ash tray would be. This was before I reinstalled all the other bits. The front face of the radio only gets warm but far from a concerning temp. The underside, back is concerning.

__________________
1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

That sounds too warm. The only guess I can make (and it is a guess) is that the car's speakers do not correctly match the impedance that the radio is expecting to see. That might cause the output transistors to overheat. Over time they could be damaged.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

Are you sure you have the wiring correct?

Was the blaupunkt you replaced it with, one that has the separate amp? I am looking for one with knobs...as the one I have lost them many moons ago...

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Left channel cutting out is your clue. Unplug the left speaker wires (front and rear) and see if the overheating stops. If it does, look for shorts in your wiring.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Valid point but the radio seems to start getting hot before anything cuts out. If it was a constant short, would I not expect to always have 1 or more speakers not working?

__________________
1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

The previous radio was a Blaupunkt Limited 1290 "High Power 2x25W." No clue if there is an amp. The Blaupunkt radio harness used the factory connectors. I connected the black female spade to the male spade next to the 4 pin connector on the Becker. The hot lead female spade was connected to the male spade on the 4 pin harness; grounds and speaker leads to their obvious connections.

__________________
1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

It may not be a zero ohm short but a partial short or mis-wire to the left speakers. Take a resistance measurement of the left and right radio speaker connectors, they should read similarly and not less than 4 ohms. You can also take resistance measurements of the radio speaker outputs and compare left and right channels. Keep meter polarity the same. Reverse the meter lead polarity also, which will give a different reading.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Heres a diagram with the color wires for the plug



Besides the plug, you should have one spade connector and that is for the antenna trigger wire...the speaker plugs are european style and no way to get those mixed up...unless they were cut.

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With the fader in the center position, I measured the speaker wires behind the radio. Both were 2.1ohms.

I guess I will reinstall the Blaupunkt radio for the time being and check if the speakers are original or not. It's kind of hard to do in the front with the dash cover over part of the speaker grille. I have some Gen 2 W126 speakers that may work.

__________________
1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

Once you remove the Becker, bench test it w a 12 V power supply and two loose car speakers.
Find out what gets warm and hot.
If you felt the heat while driving, could it have been heat up from the trans?
My 300d was like that. I put in a piece of insulation to heat shield it.

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1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
********************
1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD

That's not a bad idea at all.

The car was not even running when I felt the radio get hot.

__________________
1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge