Large Scale Central

Interesting Problem With an AristoCraft Train Engineer

Electronics Power and Sound
#1

I run three AristoCraft Train Engineers (TE). These are the somewhat later 27 mHz, 10 amp units with the later transmitters. Each is powered from a Meanwell 24 volt, 12.5 amp power supply throttled down to 22 volts. The system is set up using sp3t block switches to select any TE to any of 23 blocks of track. The system also runs a common ground between the three TEs and the a/c and halfwave d/c for the accessories, turnouts, and lighting.

Lately one of the TEs (Cab 3) developed an interesting problem. It works fine until I switch Cab1 into the control panel, even if Cab 1 is turned off. Then Cab 3 goes to 0 volts and looses its programming. I can reprogram it and it works fine again, until I switch in Cab 1.

I can switch in Cab 2 and Cab 3 does not react like this and continues to work normally. This could then indicate a problem (high resistance short or such) in the panel between Cab 1 and Cab 3.

But, if I trade out Cab 3 for different AristoCraft TE, everything works fine just as it should, indicating the panel is fine and the problem is in the TE.

Again…, it works fine and keeps its programming as long as I don’t switch in Cab 1, even if none of the block switches are selecting Cab 1. If I unplug the TE for Cab 1 from the panel and switch it on, Cab 3 continues to react normally.

At this point, all I can think to do is to check those capacitors on the board that are easily removable. If they all look good, I’ll guess I’ll just have to get rid of the unit unless someone has some other ideas.

Thanks

#2

So Cab 1 is “talking” to cab 3 and resetting it. Shouldn’t they be on different channels?

#3

They are on different channels. It is not that they are “talking” but more like Cab 1 “interupts” Cab 3 by its very presence in the system.

After open house this and next weekend, I may try using the Cab 3 TE in the Cab 2 position and see if the problem persists. Meanwhile, another TE is substituting and seems to work fine in this position.

#4

Yesterday I opened this Train Engineer to check the capacitor values. Those on the board appeared to give reasonable readings, even without removing one leg from the circuit.

But…, there is a 33 pF cap across the output terminal. I pulled this cap and it was reading ~10 pF. I replaced it with the proper value and buttoned up the unit.

Today I tried it out. After re-linking the transmitter, the voltage came up just fine on the panel meter. Then I turned on Cab 1 and brought up its voltage. Cab 3 remained on as it should and did not loose its voltage or programming as it was doing. Then I brought on Cab 2 such that all three cabs were in service. The voltage on Cab 3 remained steady and it would appear that this has fixed the problem.

Due to its placement across the output terminals, this is also the most logical analog component that would cause such a weird problem.

I did not do this with trains running (too hot today), but that wasn’t necessary to make Cab 3 fail previously and merely turning on Cab 1 would cause the problem.

#5

It sounds like one transmitter was transmitting on too broad a bandwidth, thus creating interference.

#6

Todd,

Huzzah! That was an impressive fix.