older mrc controllers


B

bristolman

Member
dumb question but going to ask anyway . when i was on line looking for info on an older mrc controller , i read that they weren't good for the newer engine because of the higher voltages sent to the engines . this was supposedly caused by the rheostat control . true or not ?
mike
 
How old do you mean by older? I have an MRC Tech 2 1500 and a Tech 2 2500. I'm guessing they are around ten years old at most even though they are in brand new condition. I bought them both used about three months ago from an online dealer in only used N scale.

These seem to work great with older and new locos. Oddly the 1500 is the one that makes the locos go the fastest......and with my microtrains N scale fast EMD FT A+B dual powered loco units....the speed is amazing and it stays on the track all the way around and never crashes. This is not particularly prototypical running I know.....but I'm used to speed testing RC airplanes and cars.

Maybe you are talking more older than this.....and I hope you get your answer.
 
bristolman said:
dumb question but going to ask anyway . when i was on line looking for info on an older mrc controller , i read that they weren't good for the newer engine because of the higher voltages sent to the engines . this was supposedly caused by the rheostat control . true or not ?
mike
Click to expand...

When can motors first came out, many of the rheostat equipped power packs didn't have fine enough control to work on these motors. Just about the only ones that did work with the can motors were the custom built transistorized control units like the simple circuits printed in Model railroader and RMC.

MRC then brought out their Tech II system which were fulled transistorized units, and could control any 12V motor. This was the early 1970's. Since then can motors have become the standard for model trains, as has the transistorized circuits of most model train power packs.
 
I've been running an MRC 501 Throttlepack since the day after fire was invented on both old units with open frame motors and some of the latest DCC ready or dual mode DCC units with no problems. I have a bunch of brass diesels I repowered back in the 70's and 80's with Sagami can motors and no problems with those either. There may be some engines that have sophisticated electronics which could be affected with overvoltage. A simple solution would be to wire a DC voltmeter across the variable output to the track and stop twisting the rheostat when it reads 12 volts.
 
wide open

when i sat the engine on the track and turned the power switch on , rheostat set to zero the engine just took off like there was no tomorrow . shut power off before it jumped the track . i put a meter on the output and it was 16 v . and the real problem is the rheostats don't work . next thought is taking it apart and see if i can find anything wrong . i just don't want to burn up new locos .
mike
 
bristolman said:
when i sat the engine on the track and turned the power switch on , rheostat set to zero the engine just took off like there was no tomorrow . shut power off before it jumped the track . i put a meter on the output and it was 16 v .
mike
Click to expand...

Many MRC powerpacks had terminals labelled "Fixed DC" or something like that. It was meant to run DC accessories or an auxiliary wired hand-held throttle.

You've probably already done this, but you might want to double-check that those aren't the terminals you had connected to the track. That output would probably be around 14-16V and wouldn't change with the potentiometer setting.

That's probably not what happened here -- probably just a busted powerpack. But I thought I'd mention it just in case.
 
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