S70 Rheostat

[garrbrick]

Hi all,

Can anyone tell me if the RHEOSTAT in S70 connects dimmable lamps to ground OR supplies variable voltage to dimmable lamps that are grounded. I don't have the vehicle available to probe and answer this question myself. And, of course, the schematics are deep under the Pentagon somewhere.

I'm testing an SC-816 on the bench and I want to be sure before I apply one of the above to the RHEOSTAT pin on the SC-816 connector. Usually instrument dimmers supply variable voltage to grounded lamps, but...?

Thanks, BH

[Bay13]

variable voltage to grounded lamps, but...?

You have it correct.

[Guest garrbrick]

You have it correct.

Well, that was quick. Thanks, Rick. Maybe you know why there is a pin on the SC-816 that is named RHEOSTAT GOUND. If the actual RHEOSTAT is a simple variable resistance path to 12 volts, what does rheostat ground have to do with anything? Unless the RHEO is actually an electronic variable voltage or current source that likes to have direct reference to the ground of its driven loads...?

Do you have access to a schematic that perhaps depicts the RHEOSTAT as an electronic module? (You know, with the little transistor symbol within the box of the module in the drawing) The rheostats of old were simple ceramic wirewound controls that could be varied and could handle a fair amount of heat dissipation as they did their work. But I wouldn't be surprised if some Swedish engineer earned a week's pay complicating that simple scheme.

Mystery.

Thanks, BH

[Bay13]

http://www.volvospeed.com/Repair/radiocon.php

A10 is RHEO input to the radio. should be a pink wire.

[the underlørd]

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