clock problem 420 sel

If fuse is bad, your entire cluster doesn't work... tach. too...

Best bet is to replace or swap out the tach/clock portion of the cluster with a working one of 86-91 gas engine unit.

Common failure on these is for the large electrolytic capacitor to fail. If that's what it is, you can remove the clock and solder a new one in. A replacement cap can be had at Radio Shack for $2. Google "mercedes clock capacitor" and you will likely find more info. But basicly if it has power and isn't working, it's worth a try. Just get a similar one that is at least as many uf as the existing one and with a 15V or higher voltage.

Cool.... I learned something new... now I need to learn how to solder an IC board...

_____ Correct. I had a failed clock in my 1985 W123 turbo diesel car. The "bad" clock was actually "ticking", but not enough energy was flowing to the stepper motor that moves the second hand.The capacitor had indeed failed, and after installing a new one it worked like new again. Soldering a new one into the circuit board is not that hard. Google "soldering techniques", and "soldering irons".

/ John

The clock board as I recall was an easy one to work on. The traces are large. One key tip, get some solder wick, which should be available at Radio Shack or similar places. It's a small copper braid flat rope that comes on a little spool. You hold it over the solder bump on the backside, place the soldering iron on top of it and press against the board while heating it. The solder melts and gets sucked into the solder wick, taking it out from around the component and board trace. After removing the part, you can use it again if needed to open the hole before inserting the new part. For soldering irons on this job, any med power pencil type works fine.

Thanks for the sugestions. Would anybody know how to remove the instrument panel?

That's easy... Get a thick wire hanger... thin one is okay too... Length is about 7"...

On one end, bend a small hook... about 1/2"

On the other end, bend opposite way of the hook for a handle... about 2".

On the instrument cluster... about 2" from the bottom... insert that tool in between the black cluster edge and the vinyl dash... It will go in... insert about 2" and turn the hook 90 degree toward the cluster... and pull out... repeat for other side.

Is that the same method for a W123 1979 240D cluster? I need to replace the dash light rheostat and fix the odometer. Thanks!

Should be. That's how my 80 300SD dash comes out. The only strange thing to be aware of is that MB in that era used mechanical oil pressure gauge, so there is an oil line going to the back of the gauge. Once you have it partially out, you can disconnect it with a wrench.