Large Scale Central

Crest revo in USA trains pa

I am helping a friend out who had one revo running 2 pa units, he blew 2 of the on board receivers. So I separated the two PA’s but they still send the revo into overload. Any Suggestions?

The Revo should be able to handle the higher current of the PA’s (as compared to Aristo locos), so I would suspect motor issues, or running high loads.

The USAT motors are known for high current draw under heavy loads, but this surprises me.

Are the stock main boards bypassed, and the revo directly connected to the motors and track pickups?

Do both locos individually put both revos into overload?

The Revo has a modicum of cooling, so could this be in a high temperature situation, or is the revo also running the smoke units also?

Greg

Greg,
Right now, they are running, directly from track to revo, the bodies are off of the chassis. I have no load other than the engine. I have a test loop in my basement with 8’ diameter curves. Yes each engine is causing each Onboard receiver to go into overload. Like I said at first I thought it was just the two PA’s hooked to one On board revo. One of the engines has a bad buzz through the speaker when I turn off the sound. Right now I am at a loss, and can’t think of what it could be.

It somehow does not make sense yet.

Try bypassing the revo, run from DC and measure the amps of each one.

Hard to believe you have 2 bad locos and or 2 bad Revo units.

We need to investigate further.

Greg

What is the power source for the track that the PA’s run on?

Mfg name and model number as we need to know the voltage and current supplied to the track.

I am using an MRC 6200, the first time the revo blew it was on a bridgewerks, the second time it was on a crest 15 amp, now they are not blowing they just go into overload.

Thanks for your help,

Nico

Are the smoke units still connected ? if so, unplug them and try again

Bill

Bill,
The smoke units are disconnected.

I have 18.63 volts dc at the track from the power pack.

Any thoughts?

Thank you,

I know nothing about the Revo system. Does it care about track polarity?

The MRC6200 only has 35va for track output.

You are trying to drive a 4x4 truck with a lawn mower engine!!

So, there is nothing wrong with your engines, it is the power source.

Read Nico’s responses, he has tried 3 different power supplies.

Also the analogy does not really hold, because even on the 6200 with limited amperage, the Revo units are showing overload.

Wrong direction, the only thing that would make them go into overload is overcurrent or overheating the Revo.

After trying 3 power supplies, clearly not the power supplies. He has tried 2 locos and 2 Revos, so it’s not really clear what the problem is.

Either there is another “sneak” load affecting BOTH Revo units (but I asked about this, both installs are to motor only, nothing else connected)

OR

Both revos are defective

OR

Both locomotives are drawing excessive power.

So, my next step would be to put an ampmeter in line with the motor and see how much current is REALLY being drawn.

Greg

Greg,

Dan nailed it, the 6200 did not have enough umph, to run it I guess. The first two power packs were used when they were linked together and blew the on board receiver.

I do find it kind of odd though, that every engine I have added a revo to was tested on the floor in my basement or on the bench with this power pack and this is the first time I ever had this issue. And I am talking some bigger engines, E8, Mallet, Mikado, Pacific etc… I am guessing that the USA PA, A unit is just a power hog.

Thanks for all the help,

We had the same issues here lately.
A fellow blew his decoder with a Bridgewerks power supply.
Turns out it was putting 38 volts on the track.
Too much for the revolution decoder.

Another guy was getting overload with an MRC unit.
I changed it to an LGB unit and all is fine.

David

So apparently the overload indication may not be really an overload.

Testing the actual current draw would have pointed this out.

So the other power supplies were used when the revo was damaged, I can certainly understand the Bridgeworks issue, that supply really should never be used when ANY wlectronics is used unless you know exactly what the input voltage limits are…

Greg

When running an engine on a bench with no load, even a 1/2 amp supply will run it.

I use the LGB 5003/110 for testing.

Bad motors show up real fast with this low current power supply.

When the engine is placed on a track, you now have the weight of moving the engine as a load and far more current is needed to move the engine therefore a more powerful supply is needed.

The thing I am curious about is the operation of the Revo in this case.

It was showing overload, which, as far as I know, is only triggered by a real overload, too much current.

But the OP now states the 6200 was the problem, and implies that a bigger power supply did the trick.

(again, it’s not a surprise about the bridgeworks overvoltage, but the crest 15 amp unit?)

So, maybe the Crest 15 amp unit is also putting out too high a voltage?

I’d like to get to the bottom of this, I think we still do not know the entire story.

Greg

Greg,
Here is the whole story. My friend had someone instal one revo Onboard to control a set of pa’s.
The first time he tried to run them they went about a foot and then died, he took the engine a part, sent the revo back to Navin and installed a new receiver. Mind you that my set of fa, FB lash up was on the same track with a revo receiver and I had no problems. This was all on the bridgewerks power supply.

With the new receiver installed we went to a different friends home with the aristo craft power supply he took the two pa’s with one revo out and put them on the track, roughly the same thing happened.

This is where I come in,

I took the two units home, with me and opened them up, the head unit with the revo had a wire twisted in one of the body screws and had all the lights blown out, I fixed the wire, and started test running, I also found that one of the wires going to the voltage regulator was chewed up. I am thinking that is what blew the lights. All testing was done with no lights or smoke on or even connected.
I thought it would be best to separate them and run them on separate revo Onboard units.

I believe that is everything

Thanks Nico… I think we have all learned a few things, which is great.

I’ll make a few observations about what I think happened.

1st go around…

From the get go, the wiring was messed up. This is probably the main reason the first Revo died. I take this from the overload (the short or nearly short), and from the fact that on the same track with the same power supply with a Revo, another loco was fine.

2nd go around…

It’s not clear, but I’d guess you had at least one loco still giving you fits.

3rd go around…

Bad wiring fixed.

One thing that I asked very early on, was “Are the stock main boards bypassed, and the revo directly connected to the motors and track pickups?”

Clearly not ALL of the original wiring was bypassed. I think I learned to make sure I get the answers to specific questions, because I would have gone down the “wiring problem” path sooner.

Glad you got to the bottom of it, which was indeed not the motors, nor the power supplies, but the actual installation.

And I agree, with the potential for pretty high current, I would use a Revo per loco.

Regards, Greg

Ok, next question.

Does anyone have any experience with the lighting and the revo in a USA trains PA.

Right now it is still going through the circuit board in the PA. So depending on track polarity they are either on or off, and direction will not change the lighting. The board is putting out 5 volts.

The revo board puts out full track voltage, and does not flip with polarity, it is either on forward or on back.

Any help is appreciated,

Thank you,

Nico