Large Scale Central

Crest revo in USA trains pa

Problem Solving
#13

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,

#14

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

#15

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

#16

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.

#17

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

#18

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

#19

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

#20

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

#21

Deleted

#22

Nico Corbo said:

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

Nico - Are you powering the circuit board with the lighting output from the Revo? I’m not a Revo guy, but I would expect there to be two lighting outputs, one for forward and one for reverse. The operation you describe sounds logical if connected to one of two lighting outputs.

The best advice is probably to eliminate the circuit board and power the lighting directly from the Revo. I’ll defer how to do that to someone who knows the Revo. -OR- Forget the lighting output on the Revo and connect the circuit board to the motor output. It should then function just like when on direct track power.

#23

Back to the initial question I asked, hmm…

OK, best suggestion:

Pull the incandescent lights out and run LEDs right to the decoder.

Trying to make the existing lighting and circuitry work is really a waste of time… If you want to do that, you probably need a bit more experience, no offense.

If someone was holding a gun to my head, then I would do like I did on my F3 units, investigate the existing lights and power supplies. In my F3 I found 3 different voltages running different lamps. If that does not scare you it should.

A way that some people try is to switch the regulator circuit on and off, but you also want directional lights. It can be done, but it takes a little creative wiring and figuring out.

Most people that try this wind up blowing half the lights before they get it working… and now that means the effort to replace the lamps with LEDs is a straightforward mechanical exercise followed by simple straightforward wiring, i.e. less work.

I know how to do it, I can even write it down, but I don’t recommend it, and I surely don’t want to be to blame for “bad instructions” on a tricky task.

Bottom line: this loco was designed for track power, on board regulators, all different incandescent bulb voltages, and negative common. You want to use what is basically a constant voltage source for all the bulbs and you need a positive common. Too much to rewire and figure out to preserve the original lights and wiring.

(yeah, I know, you just want the headlight… oh, and the number boards… oh and the cab lights… and then finally the dreaded bicolor bipolar LEDs that are classification lights… too much to try to adapt)

Greg

Nico Corbo said:

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

#24

Greg,
Going from the main board to the light board is 5 volts. Are you saying they even drop down further on the light board?

Thanks again, you have really been a big help and no offense taken, I know enough about electronics to be dangerous.

#25

I generally don’t post on issues like this as I’m certain there are folks more experienced than I in the workings of large scale locomotives but here is the gist of what I found and did with a USA GP-7 recently. I have a PA but have never looked inside so this may not apply but since both of these locomotives are about the same age design wise I’m going to assume the electronics for the lights are similar.

I am not going to post schematics or go into detailed instructions but provide an overview to give you and idea of what may be involved. As Greg said the whole shebang is designed for track power and the board depends on track level voltage and polarity reversal in order to work as designed. My first thought was to just connect the motor output from the REVO to the board.

The main issue with that is if you use PWM the regulators on the board don’t like it and the lights will not come on until you reach nearly full speed. I looked at replacing all of the bulbs and bipolar LED’s but it looked like more mechanical and wiring work than I wanted to do.

Being an old guy who spent a lot of years building circuits on perf board I went that route. I used two DPDT reed relays and powered them from the REVO light outputs. They switch the straight battery voltage to the light board, one of them straight through the other reverses the polarity. I could have done this with one relay but as long as the battery was on one direction of lights would be on, with two when the REVO outputs are off so are the lights.

This worked and the only initial problem I had was when I went to link the REVO receiver to a transmitter. When this is done the REVO flashes both headlight outputs and when both relays energized it blew one of the relays as it shorted the battery voltage. I did have a fuse but it was too slow. It just means that if I ever need to link again I just disconnect the relay board before doing so.

While this does require some expertise that you may not have in my case I felt the board and wiring it between the REVO board was much simpler than rewiring and replacing all the lamps and LED’s . I reused the connectors that came with the unit and the relay board plugs into the light board where the track power originally did.

As Greg cautioned if you are not comfortable doing this sort of thing or don’t have the experience level you are best of leaving it alone or letting some one more experienced do it, mistakes can be expensive and replacement parts hard to come by.

#26

Here’s likely a solution from ignorance:
Having little knowledge of wiring problem/solutions, I wire my headlight and cab lighting for my four steamers and modified diesels directly to wiring powering the motor. Using 14 volt bulbs – mircro and larger – works OK since most running voltages are within that range and maintain enough light to be effective. Granted, loco speed is the determinant of light generated. Most of the time our trains run at a constant speed, so the illusion of constant light is there.

#27

Nico, I actually answered your question before, but the answer is that my experience with the F3 units showed THREE different voltages for lamps, there was some extra circuitry on the light boards.

Again, as you get further into it, I believe you will find another and then another “stopping point”.

I’m trying to convince you to change to all LEDs and bypass the existing electronics completely both the regulator(s), dropping resistors, and the different lamps used.

Gary, the regulators would NEVER be fed from the PWM output, that should only go to the motors, the regulators should be fed directly from the battery. One of the main issues here was that the lights were indeed somehow fed from the motor outputs, wrong circuitry for conversion to a constant voltage supply system, whether battery, or something like DCC.

Regards, Greg

#28

I was thinking of putting a bridge rectifier in line with the power supply wire to the lighting board this way the lights are always on wether the engines are running forward or backward and the polarity from the power input from the trackwill not affect the lighting.

What do you guys think about that idea?

#29

I’m almost speechless ha ha!

So the lights on all the time with no direction control is ok?

Greg

#30

Greg, yea, of course, if you only run the locomotive forward in a roundy round, having the headlight on all the time is ok.

:slight_smile:

Yes, I am kidding.

#31

The main circuit boards in USA Trains diesels that have the LM317 voltage regulator for the lighting circuit boards cannot be powered with the PWC (motor) output of the Revolution receiver. As previously posted the lights will not work until maximum voltage is reached.

Adding the Crest PWC to Linear DC board (CRE 57091) between the receiver (motor) output and the USAT main circuit board will resolve the problem however, as it provides linear DC power. But its components draw power, so the lights may not come on before the locomotive moves.

(http://freightsheds.largescalecentral.com/users/son_of_a_cnr/CRE57091.jpg)

The main circuit boards in some USAT diesels like the SD70 and S-4 have large dropping resistors instead of the LM317 voltage resistor. They can be powered with the PWC (motor) output of the Revolution receiver and the lights should work.

The Revolution receiver is designed with three lighting connections. HD COM is normally positive. On the Revolution receiver WITHOUT SOUND there were diodes on the board to ensure HDCOM was always positive. On the Revolution receiver WITH SOUND they appear to have been removed. I believe this why the Bachmann locomotives with Plug and Play sockets worked with the old receivers, but not the new ones.

The Plug and Play boards and receiver adapter boards also have diodes on them to ensure HDCOM was always positive. They are labelled D1 and D2.

(http://ovgrs.peterbramahphotography.com/wp-content/uploads/2013/07/Receiver31.jpg)

The HD1 and HD2 light connections are grounds. The Revolution receiver connects or disconnect the grounds to provide directional headlights.

Unfortunately USAT lighting circuits boards normally have a common ground and two positive feeds: one for the headlights and another for the cab light and number board lights. This makes it difficult to wire them directly to the Revolution receiver. They also draw a lot of power, the reason I think USAT diesels are labeled as power hogs. Like George Schreyer I found it easier to remove the USAT lighting boards and make my own.

If battery power is used the USAT lighting circuit boards can be removed and replaced with LEDs. This is what I did for my GP-9, GP-30, NW-2 and S-4 projects which are on the Ottawa Valley GRS web site.

If track power is used, additional components would be needed to ensure that HDCOM was always positive and the ground for the number board lights was always negative. I saved this schematic for powering LED from track power, although I don’t remember where I scooped it from.

It uses a CL2N3 LED drivers available from Mouser Electronics.

Although I have yet to use them in a diesel, I do know that a diode must be used to protect these devices when polarity changes are expected.

#32

Paul, if those were 5v lamps for example, then a 1k resistor could have 20 volts across it.

So V=IR, so current is 20 milliamperes.

Power is = IR = .4 watts

I gather you are using 1 watt or greater resistors?

Greg