Hi all,

In my seemingly never ending quest to restore my 1990 240DL (sedan) back to original condition, I spent today at the junk yard.

I pulled an OEM power antenna (works) and a CR 712 Casette deck. The 3A fuses were blown, so I replaced them before installing. I was able to connect that up to the 9pin square harness and antenna banana plug.

That powers on, and seeks channels, but that is roughly where the excitement stops. Very faintly can you hear audio coming out of the speakers (speakers and wiring worked fine -- I have been using a "nicer" (er, that is, newer, aftermarket (yuck)) unit just fine. (The wiring would take some time to explain, but short version is that the 9 pin header in the dash is unmodified.)

I suppose in all likelihood the 2 channel power amp section IN the unit (that would power the front speakers) has blown.

I think easiest option would be to try and find another CR712 that is known to be working.

Does anyone have one they want to sell me?

Or any idea in the least how to fix the one I have?

Thanks!

 

take it apart, look for leaky or swollen capacitors, unsolder and replace them with matching components. while you're at it, clean and lube the gears of the cassette mechanism, as the old grease is probably turned to wax, and replace any rubber band drive belts, its probably hard and cracked. even so the capstan roller is probably hard as a rock and the tape speed might slip

 

There have been numerous changes in radio broadcasting over the decades since these cars were new. I'm not sure how much that might impact an old stereo.


I know in my job 2 way radios have changed considerably with frequencies being cut in half by the FCC (narrow band). During the transition a narrow banded radio trying to talk to a wide band radio was just a whisper, wide band to narrow band was the reverse the radio was screaming in your ear.


There is also the switch to digital in some areas, the old analog radios can't receive the broadcast from a digital station. I've run into that with much newer radios (switch began to occur in the mid 00's).




I'm kind of in the same boat, not stock but I've got an aftermarket stereo, but one correct for the age of the car (1980s Alpine). It was a high end stereo back in the day but honestly the sound quality and reception isn't that great. The practical daily driver part of me wants to replace it with a modern stereo, the nostalgic, period correct part of me wants to stick with the old one.




Or maybe it is just because they are old, not sure anyone expects a stereo to last 30 years.

 

basic AM and FM broadcasting hasn't changed one bit since it was created. FM added stereo in a compatible fashion in the mid 1960s (so a FM mono radio still gets a mono signal from a FM stereo broadcast). they added optional digital "HD" radio some time in the 2000s, but A; hardly anyone is broadcasting it, and B; it doesn't affect conventional analog AM/FM. I've not heard of any stations broadcasting HD digital only.

radio recievers, the tuner sections improved signficantly in the mid 80s with the introduction of 'phased lock loops' and again more recently with digital frequency synthesis, but these just give you more stable and cleaner reception.

the amplifier section of in-dash stereos are WAY better now than they were 20 years ago, with almost every stereo outputting like 50 watts 'music power' per channel by using 'class D' digital amplifier techniques... older car stereos couldn't do more than about 17 watts peak music power into 4 ohms, and even then they generated a lot more heat than today's class D amplifiers.

 

I got one from this guy who is in the salvage business . He had a few of them last year. Drop him a note and see what he has. George Glovier eden11@comcast.net