Over Heating

[SvFiat]

About a month ago I started to get back into model trains. I purchased the dcc set with the ez command control and 2 dcc engines. Everything ran fine after the usual fine tuning. I then purchased the Dynamis controller. Now one of the engines runs at about half speed and gets very hot.

With the ez command in the system the track voltage ran between 18-19 volts AC and with the Dynamis in the sytem it's 14-15 volts AC. What is the correct operating voltage for these dcc units?

TIA. 

[Daylight4449]

No! i use dc but in ho, unlike o ac is not for track in any circumstance.

[Guilford Guy]

Only one of the engines? I'm assuming the track is plugged into the DC outlets. Normal operating voltage is 12 volts DC. Does the malfunctioning locomotive work normally with the EZ command? Which locomotive is it specifically?

[richG]

Many DCC systems operate between 14 vac and 16 vac. My NCE operates at 13.5 vac. I measure with an oscilloscope. It is near the DC level indicated on the wall wart and a loco operating on the track. Using math, I convert the values to what manufacturer specify. Some digital voltmeters will read in the vicinity of 14 vac. Some will show quite different voltages. There is no DC on the tracks for DCC.
Have no idea why more heat at lower track voltage.

Some DC power packs put out DC with pulses which will show up on the AC scale of a voltmeter. Some cheap DC power packs do not filter out the AC very well and AC voltage can be riding on the DC voltage. Normally not enough AC to affect the motor.

Rich

[SvFiat]

This all Bachmann equipment straight out of the box. I Have 4 GP 40's not that makes a difference. What is interesting is that all have different circuit boards:

H601X-PCB01 Rev C     04/06/04
H601X-PCB01B             04/05/06

And the 2 I'm not having problems with have the same circuit boards:

RoHS H601X#PCB01 Rev B     06/11/11

there's also slight differences in the frames in the later.

[Jim Banner]

I don't know the answer but I have a few thoughts for you.  The first is to determine whether this is a mechanical problem or an electrical problem.

Mechanical problems would be things like lint/hair wound around an axle or a shaft in the gear tower, lack of lubrication somewhere or something else causing extra drag.  Turning the motor shaft by hand will often show that something is dragging, particularly when you have a similar locomotive that runs well to compare the faulty one to.  If there is extra drag, a careful examination with a magnifying glass will often help locate it.

Electrical problems that can cause overheating and slow running would most likely be in the decoder or the wiring to it.  Any problems in the decoder are best considered unrepairable and will require a replacement decoder.  Wiring problems to look for would be accidental contact between either motor connection and either pickup (wheel) connection.  I am not sure if the path from wheels to decoder includes the metal frame on these locomotives, but if it does, then an unwanted connection between a motor wire and the frame could also cause a problem.

There are a couple of test you could do.  One is to try running the faulty locomotive with the old E-Z Command, if you still have it available.  This might indicate that the problem is coincidental to switching to the Dynamis and not caused by it.  The other is to see whether changing the dc on the track makes any difference to the faulty locomotive when it is running on DCC.  The dc is controlled by address 10 on your old E-Z Command.  As the Dynamis does not support dc operation, this test cannot be performed with it.

As to correct voltages on the rails, most DCC systems put out around 14 to 15 volts ac.  The E-Z Command puts out a couple of extra volts when measured with no load (no locomotives running.)  Many DCC systems can also put out about 10 volts dc on the rails.  This allows you to still run your old fashioned dc locomotives until you get around to upgrading them with decoders.  The fact that DCC uses ac power on the rails serves to confuse and confound the dc guys who are well aware that the permanent magnet motors in our locomotives must have dc to run.  But rest assured, your working decoders are quite good at converting the ac to dc and massaging it in wonderful ways to fully control your motors.  Using some dc on the rails along with the DCC power can help determine whether the "faulty" decoder is doing its job properly.  The locomotive speed should not change when it is running on DCC and you change the dc on the track. 

[SvFiat]

Jim, I appreciate the input and having said all of that.....

I thoroughly check through these engines and found that the wires to the motors were running dangerously close to the frame so I moved them a tad and put some electrical tape in there to really isolate it. I also really inspected the solder joints and found some suspect ones so i hit them with an iron. One of the engines perked back up the other is still running slow.

So I guess the next question would be who makes a reliable decoder, and since I'm going to go through the headache of installing one or two, I might as well get ones with sound.

All suggestions welcomed !!!!