1987 w124 300 TDT

My radio (factory original) has been acting funky for a couple of months and I am suspicious it's connected to battery drain problem. The issue is that it occasionally works but most often doesn't. When not working, I can play a tape based mp3 connector, but the volume is fixed and way low. Also, the antenna stays up when I turn off the car though it will go down via the switch. The battery frequently goes dead if the car sits long and when I jump start it, the radio works normally until I turn off the car. It occasionally looks like the stereo indicator lamp on the radio is lit, but I am not sure.

I thought this might be tied up with where I was drawing switched dc power for my grease car kit, but I tried switching the source and the problem hasn't abated. I have had a couple of perfect storm events where this issue coincided with a loss of fuel prime. It is hard to crank the fuel system full with a dead battery. Thanks for your help.

I forgot that I took photos of a couple fuses outside the fuse box, one of which is definitely blown. Could there be a link? I can't upload the pics now, but the fuses are both glass cylinder type and enclosed in plastic holders. One is on a red wire leading from the firewall to the fuse box in the engine bay and the other on a white wire.

When you get done using the mp3 adapter, are you leaving it in the cassette player or ejecting it?

The reason why it sounds crappy is because your heads are dirty.....if you look inside the cassette player, you can see the head.....rubbing alcohol on a cotton swab will clean it....chances are you'll need multiple swabs until they become clean..

The antenna wire on the back of the radio maybe disconnected causing the issue...

I am not sure what type of fuses a w124 uses but confirm they are the proper type and are the right amps...

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The sub par sound is not the result of dirty tape heads. I cleaned them a month or so ago and when the radio is functioning the sound is good. When it is misbehaving, the volume is way low but if I hit the on button I get a very brief spike in volume. I confirmed yesterday that if I hit the on button while the radio is misbehaving the stereo indicator behaves as if the radio is working.