In preparation for DC conversion, I tested 5 HO locos, three Atlas and Bachmann were from the the 1980's, the Life Like Proto 2000 was later I guess. Harbor Freight voltmeter hooked up in series with a MRC Railmaster 2400
The Bachmann GP 30 had the highest stall current of 1.1 amps, it was also the noisiest and from what I read about DCC conversion of this unit, it may go to the graveyard.
Atlas S4 1.0
Atlas RS-1 .92
Proto 2K GP7 .78
Atlas RS-3 .95
The first four ran around the loop with an amp reading of .25 - .5, each one relatively constant.
The RS-3 had amp readings of .2 to 8.1 and all numbers in between while runing!!! I repeated the testing a couple times and it was absolutely reproducible.Surely it's not drawing 8 amps. I guess something must be shorting, but it is not obvious by change in engine speed. Would a short in the brushes do this?
Henry
COB Potomac & Northern
Shenandoah Valley
can your power supply supply 8 amps?
greg - Philadelphia & Reading / Reading
The Internet says 1.65 amps and "will power two locos. It does shut down if there is a short. 8 amps sounds like a lot to me for a HO power pak.
Why would there be voltage spikes on just one engine?
No more ideas?
If it's electrical noise coming from the loco, should I be concerned with that? Is it still a candidate for DCC conversion?
Does the RS-3 otherwise run OK on DC? No stalling, no stopping where it won't restart itself? The Kato motor would melt if it really were suckign down 8 amps, but I HAVE seen one where it was sloppily assembled and there was excess adhesive oozed on to one of the commutator segmens, causing the motor to sometimes stop on that segment and then not be able to start again unless the flywheel was advanced slightly to get the chunk of glue ou from under the brush. However that did not make the motor consume 8 amps. The othe rpossibility is a burned winding, if some of the enamel insulation has cooked off on one of the windings, it could be shorting and instead of having a few hundred turns it may only have the equivalent of 10. Use the meter in ohms and measure across the brushes (disconnect the motor leads from the 'board' or you'll have the light bulb in parallel messing up every measurement). Turn the motor slowly by hand and watch the readings at each segment - it will jump as you cross segments and the brush contacts two segments at the same time but then should eb stable on each pairing. The readings should all be approximately teh same, if one has significantly lower resistence, you have a burned out armature. You can still get replacement motors if needed. If everythign checks out, then the odd reading may be just electrical noise, but unless the brushes are badly worn there's really nothing in there that woudl generate excess noise. There are no components, and the circuit 'board' is a plastic piece with two long stiff wires for the pickups, clamping the motor leads and the light bulb in the middle.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
BigDaddy No more ideas? If it's electrical noise coming from the loco, should I be concerned with that? Is it still a candidate for DCC conversion?
Out Of curiousity.....put a fas-blow 3/4 amp fuse in-line with DC to track. 8 amps?...out of the question with that power pack...it would overload and shut down...just like a short....which You don't have.
Good Luck!
Frank
BigDaddyThe Internet says 1.65 amps and "will power two locos. It does shut down if there is a short. 8 amps sounds like a lot to me for a HO power pak. Why would there be voltage spikes on just one engine?
doesn't make sense that a throttle rated 1.6A is supplying 8A.
There wouldn't be a voltage spike unless there were something wrong with the trottle. An intermittent short would draw an excessive amount of current causing the voltage to drop, not spike.
as Randy asked, is the loco running smoothly?
do you have another metter?
I seem to have previously blown the fuse in my Craftsman multimeter. They are in stock at the local Sear, but 200,000 people are on that road tonight traveling to Ocean City MD. A 15 minute round trip might take an hour. Tomorrow might not be much better.
However, measuring voltage with the HF and it was all over the place. With the Craftsman it was constant. No idea what to make of that.
I have no quick blow fuses and Radio Shack's stock of stuff that isn't cell phone related is pitiful.
I will report back when I have new info.
PS The loco runs great. You could not pick that one out of the 5 as having a problem.
Voltage all over the place is probably a sign of poor pickup contact, no load voltage vs loaded voltage. I find the HF meters work perfectly fine for checking plain DC voltage and current draw.
Sorry i forgot to get back to you guys about this. Another HF meter and a Craftsman meter did not show these wild swings. It seems to be the connection in the 1st HF monitor where the probe plugs into the meter.
Stick a fork in this thread.
I can agree, the HF meters are quite good for the price. I have had four HF meters for some years.
I only get issues when the battery runs down to a certain point.
Some years ago I bought a pack of fuses from my local Radio Shack.
As an extra, mine read 13.6 vac with my NCE Power Cab and agree with my Scope.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.