Author Topic: Cleaning Rheostat  (Read 5457 times)

seawolf71

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Cleaning Rheostat
« on: September 15, 2010, 00:47:29 »
Hi-Does anybody know where to get the "Tuner cleaner and Lube" mentioned in an earlier post? My rheostat works(3 to 18) ohms but I'd like to clean it before I put it back in. Thanks Bill 71 280 SL

280SL71

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Re: Cleaning Rheostat
« Reply #1 on: September 15, 2010, 09:05:11 »
In the USA try Radio Shack or similar.

Richard M, NYC
1969 280 SL, Tunis Beige, Euro Model (Italy).
Can be seen at www.panix.com/~rmadison/mercedes.shtml

graphic66

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Re: Cleaning Rheostat
« Reply #2 on: September 15, 2010, 13:28:13 »
I also apply some silicone dielectric grease to the contacts after cleaning. It helps lube the little slider and make good contact

al_lieffring

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66 230SL

seawolf71

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Re: Cleaning Rheostat
« Reply #4 on: September 15, 2010, 16:02:05 »
Thanks Richard,Al, and graffic66 for the info. My rheostat looks different than the picture in the Tech Manual-shorter shaft-was it separate from the center cluster in the 230 & 250 ? Also graffic66-first use the tuner spray and then the dielectric grease-do I have take the rheostat apart to do that or can I leave it attached to the bakelite? Thanks again. Bill 71 280SL

graphic66

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Re: Cleaning Rheostat
« Reply #5 on: September 15, 2010, 17:25:59 »
First cleaner, then dielectric, probably best to leave it together. Be careful of the ceramic part, it cracks easy. You may want to use some emory cloth on the contacting surfaces if they are not smooth and clean.

al_lieffring

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Re: Cleaning Rheostat
« Reply #6 on: September 17, 2010, 13:04:29 »
My rheostat looks different than the picture in the Tech Manual-shorter shaft-was it separate from the center cluster in the 230 & 250 ?

The illustration in the Tech Manual is a rheostat used in the 108,109,114 and 115 Sedans, not sure why. The sedan rheostat plugs in to the circuit board on the back of the instrument cluster. On thehe 113 pagoda the wires are soldered on. Some of the internal components are the same, but the sedan and pagoda rheostat are not interchangable. 230 250 & 280sl are all the same, also the same as the 111 series 220se,250se and 280se coupes.
66 230SL

mdsalemi

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Re: Cleaning Rheostat
« Reply #7 on: September 17, 2010, 14:16:53 »
As food for thought, if you have a marginal rheostat, a consideration is bypassing it altogether (this is what Palo Alto does regularly).  Reasons for doing so?  First, they can and do give trouble over the decades have many have found out.  But more importantly, at the full on setting, the dash lights are considerably dimmer than a modern car.

Mine was "repaired" to working standards, but has been set on full bright and never moved--in fact, I wish it were brighter like my daily drivers...
Michael Salemi
1969 280SL (USA-Spec)
Signal Red 568G w/Black Leather (Restored)
Novi, (Detroit Area) Michigan USA

seawolf71

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Re: Cleaning Rheostat
« Reply #8 on: September 17, 2010, 15:48:15 »
Thanks Al and Michael for the info. I was really puzzled about the difference between my rheostat and the one in the Tech  Manual, but just assumed that it was from an earlier 113. Palo Alto Speedometer rebuilt all my Dash instruments 3 years ago and I'm finally putting them back in. I want to test the rheostat ( I put an ohm meter on it and got 3-18 ohms ),but I'd like to use a 12 volt source-no battery in car- so that I could be sure and see how much light I get. can I put power to the 12 prong that comes out of the back of the center cluster or do I have to assemble it and then test? I would also like to test the blower since I don't recall it ever working.Palo Alto said they weren't sure if the rheostat worked but there is no bypass wired up. Thanks again for sharing your knowledge!  Bill 71 280SL

ronaldward

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Re: Cleaning Rheostat
« Reply #9 on: February 02, 2013, 13:17:32 »
Have 1970 280SL. Instrument lighting rheostat knob turns without any change in lighting. Lighting is always on and on dim side. Is it worth the effort to take it out, clean it, i.e. will this make it function better.

w113dude

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Re: Cleaning Rheostat
« Reply #10 on: February 02, 2013, 14:32:18 »
Have 1970 280SL. Instrument lighting rheostat knob turns without any change in lighting. Lighting is always on and on dim side. Is it worth the effort to take it out, clean it, i.e. will this make it function better.

It may or may not depending on how bad the unit is, it might be best to look in to by-passing rheostat all together so you'll have bright light at all time, I think the information is in the tech section as to how to do it.
Shaun Pooladian

67 250SL Auto late, Euro under restoration
70 280SE Coupe factory 5speed
72 250C  (for sale)
80 300CD, converted to 4sp manual, every day driver