MRC Tech II controller mods: Adding panel meters

[DrifterNL]

@Metrolink Where is the yellow wire (coming from the momentum switch going to the board) connected on the board?

YWH-2.jpg

[Mac]

@DrifterNL -- One thought -- can @Metrolink just move the direction switch to be the last thing in the circuit (after momentum etc...)? This would let him connect the sensor after momentum but before direction switch / polarity issues. it is just a switch so should be easy enough to bypass it where it is and then reconnect it later in the circuit.

Never supposed to throw direction switch without turning down power so should not be a problem if it was incorporated later in the circuit (anyway changing polarity at full throttle would be just as much of or more of an issue than changing polarity as momentum ramps up or down or something).

I don't have momentum in my 55's so I can just connect prior to the direction switch -- guess I will need to open them up.

[DrifterNL]

@Metrolink
Another question:
Are the diodes connected and oriented (white stripe) on the board like the picture below?

FBR-2.jpg

[Metrolink]

Where is the yellow wire (coming from the momentum switch going to the board) connected on the board?

Yes! The yellow wire from the momentum switch connects where your yellow arrow is pointed.

Are the diodes connected and oriented (white stripe) on the board like the picture below?

Yes, correct again! As your drawing indicates. Dang, you're good!

I see how the PCB is attached now. I don't have the tool to detach it easily. I'll try to get it off tomorrow, and post a photo of the top side of the circuit board for you.

[DrifterNL]

@Metrolink

OK, from the info I found (and if I'm correct) it looks like you can connect the panel meter as shown in the picture below with one exception:

3000GSopenVAconnection-2.jpg

3 pole connector:
Red wire -> connect as indicated.
Black wire -> connect as indicated.
Blue (or yellow) wire -> de-solder the green wire coming from the direction switch going to the PCB on the PCB side and solder the green wire to the blue (or yellow) wire and insulate.

2 pole connector:
Red wire -> Don't connect as indicated* but connect to the + of a 9V battery.
Black wire -> connect to the - of the 9V battery.
* I'm doing this because I don't trust that 50VDC you measured.

Connect everything up and test:
Magic blue smoke -> indicates that something went horribly wrong.

[Metrolink]

Awesome! Thanks a lot man! I swear, I don't know why my meter read such high voltages? I checked the scale settings like four times. At the 15VDC scale, it immediately pegged the meter. The next scale up is 150VDC, and that's the readings I got.

[Mac]

Hope this project is going well -- my semester started so have not had time to work on the layout or anything. I did come across an interesting MRC controller that has built in meters. Search on "mrc tech3 9500" (I see lots of Tech II and Tech 4s but had not seen any Tech 3s). Posting this as more of a curiosity since both you and I have committed and purchased multiple count of another transformer / controller.

[Metrolink]

Yes, I've seen those, thanks! I think that may be the one that puts out too much power for N-scale.