N scale layout- HELP!!

Point353: AHA! Atlas Snap Relays for switching the turnout position indication lights on the control panel! That makes sense. And along with Doug's observation that there are 3 power sources, might also offer a clue as to why some switches aren't working: There may need to be a 4th power source.

Curt, I suspect there are 5 color-coded blocks that are electrically separated by insulating rail joiners in both rails wherever two colors meet each other: 2 outside loops--Blue and Yellow; 2 inside loops--Green and White; and a Red block connecting the Blue outside loop to the Green inside loop. Although the control panel shows a Tan (?Mauve?) block to the turntable and 2 spurs in the middle of the layout, there is no rotary switch to assign Cab power to that block. If there are insulating rail joiners between the Red and Tan blocks, power up one Cab at a time to see which one provides power to the Tan block.

There are 4 Cabs (the rheostats on the control panel marked A, B, C, and D) which provide power to the blocks. Cab power is routed to those 6 (or 5) blocks by the rotary switches. The control panel suggests the layout was originally designed so that Cab A and Cab C could power trains in all 5 block, Cab B only powers trains in the Blue and Yellow blocks, and Cab D only powers trains in the Green, White, and Red blocks. My guess is that one power pack supplies track power for Cab A, a second powers Cab C, and (if there is not a fourth power pack), the third powers both Cab B and Cab D.

It seems likely that each Snap Relay controls whether the panel lights associated with a particular switch machine are green/red (or on/off, or thrown/closed). And also likely that the discharge capacitor drives both the panel lights' Snap Relay and the switch machine's solenoid. Does the discharge capacitor get its power from the AC or DC accessory terminals of one of the MRC power packs, or from a separate power source (or maybe a wall wart)?
Where do the panel lights (that are turned on/off by the Snap Relay) get their power from...a second MRC power pack, or from a separate power source?

For any switch machine that is not working, is there power to its associated Snap Relay? (i.e., does the snap relay click back and forth when the control panel buttons are pushed?) If so, check whether or not there is power to the switch machine power input terminals of the Snap Relay. If so, check whether there is a voltage spike showing on the switch machine power output terminals of the Snap Relay at the moment of clicking. If so, isolate the switch machine (disconnect it from the any power source), and then check if the switch machine has been burned out by confirming continuity through the switch machine solenoid of green to black wires and red to black wires when the switch machine has been manually closed and thrown.

 

In2Tech: Different school districts (and often different grade levels within the same district) have their own policies and procedures regarding student and faculty access to the Internet. Typically, setting up a classroom web page would need to be approved by the district administration and managed through the building or district tech department...certainly do-able, but school districts might be more willing to provide a space somewhere in the school building's or district's network [that is only school- or district-wide, rather than world wide] for the students to upload layout pics and videos, because there could be much better security and closer management of student content.

TrainBoard is a family friendly site, but we only have a handful of members who are minors. Minor members have parental permission to post on TrainBoard and upload pics to RailImages, and are subject to the same limits and latitudes as adult members.

 

You may have already done this, but just in case...
The repeated opening/closing of the control panel may have caused some wires to come loose or to touch where they should not be touching, causing a short (and/or the subsequent overload). Start troubleshooting from your power source.

1. Disconnect all output wires from the power pack (both DC track power and AC and/or DC accessory power). With the power pack plugged in and turned on, if the overload light that was on, has now turned itself off, and if all other lights on the C power pack seem to be going on and off the way they should, then measure the DC track power output coming directly from the power pack terminals when you turn the power pack knob from 0 to 100% power.
If the power pack in NOT working, you may want to buy a 12 to 16 volt power source.

2. If you can get a range of power from 0% to 100% full power directly from the power pack, re-connect the track power wires to the power pack but keep them disconnected from the C potentiometer at the other end. Don't connect any accessory power wires, yet.

3. If you can get full power at the end of the track power wires where they will connect to the potentiometer, isolate the potentiometer from the rest of the layout and reconnect the C power pack to the C potentiometer; turn the power pack on and dial it up to 100%; then measure the potentiometer's output as you turn the potentiometer's knob from from 0% to 100%. Assuming the potentiometer knob is tight and the potentiometer is working properly, then every incremental change in the position of the potentiameter's knob, should result in a proportionately incremental increase in the voltage from 0 volts to close to the voltage measured at the power pack terminals.

4.If you get no change in voltage for the first few incremental position changes of the knob followed by a sudden jump from 0 volts to 4 or 5 volts, it probably means that you will need to replace the potentiometer. If you don't have a Radio Shack or comparable shop near you now, you can get an inexpensive replacement from online companies like Allelectronics.com (that are probably smaller, but hopefully more reliable than what you are replacing). If you describe your application, a good electrician or electronics repair person could probably tell you the proper size (number of ohms) and wattage to get.

5. If the potentiometer is changing its output as it should, then, re-connect one pair of the C block track feeder wires to the potentiometer at a time, and re-test how the potentiometer is working after reconnecting each new pair to all the various tracks served by the C Potentiometer. If problems arise, check that the positive and negative terminals are each connected to the correct (inside or outside) rail, and also that there is no other connection of any C block tracks to either the B potentiometer or the A potentiometer.

Good luck! Overall, this sort of troubleshooting isn't that complicated--just take one step at a time--but it certainly can be tedious, and often is frustrating or even crazy-making when shorts or broken connections cannot be readily identified. Please keep us informed about your progress as you go along, so we can offer congratulations or commiserations, as needed...and maybe even answer a question or recommend a new direction.