My tachometer on my 1982 300D has a mind of it's own. Sometimes it works perfectly and sometimes it flips around all wacky, then goes back to normal. Anyone have some insight to this one? The grey cable seems to be ok. Other than that my car rocks.

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1982 300D Turbo "Helga"
380,000 miles

I'm not sure what you mean TXBill. I did the search but...Forgive me for being clueless, thats why I joined this forum.

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1982 300D Turbo "Helga"
380,000 miles

Thanks TXBILL! That actually helped alot. I'm new to this website and am still learning how to find things on it! G'day

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1982 300D Turbo "Helga"
380,000 miles

Brad, The permanent fix to your tach problem is to remove the circuit board and re-solder the connections as Longston indicated in his post. The cigarette trick is only a temporary solution. Be very careful in removing the silicon from the trace side of the board. It is not necessary to remove silicon from the component side of the board in most cases. Good luck.

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Richard Seaman
1982 300D Turbo 198k
1987 420SEL Sold
1993 400SEL 123k
MBCA Desert Stars

Yes, I resoldered the tach amp on 2 of my cars. WHAT A PAIN. it took me about an hour to remove all the silicone from the board and about 10 minutes to resolder it! But worth it, being a new one is $70 if i remember correctly.

I tried the cigarette butt trick and it seems to be working for now. I will probably just replace the component at some point as I intend to keep the car. Sun Valley Mercedes (California) says they have the part new for $35.00. Good deals to be had there on new and used parts!!!

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1982 300D Turbo "Helga"
380,000 miles

Hey yall,
I just ripped all the latex off of my tach sending unit and can't seem to find any of the soldering problems everyone is talking about. What am I supposed to be looking for, and does anyone have a picture of what it is all supposed to look like?

Thanks,
Paul

Paul, You have to look on the trace side of the board with a magnifying glass to see the points wher a lead from a component comes thru the board. You will most often see a small ring around that point, Carefully re-solder those that look bad. I had to do mine twice since some that did not look bad actually were. DO NOT over heat any connection, or else you could destroy the component on the other side of the board. Just enough heat with a low wattage soldering pencil will do it.
Good luck,

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Richard Seaman
1982 300D Turbo 198k
1987 420SEL Sold
1993 400SEL 123k
MBCA Desert Stars