I have a transformer/powerpack, MRC 6200. The pack is rated at 60VA 0n the 0-18 circuit. The transformer will run a single can motored engine ok, when a second engine is added they will run together for a short time and then the transformer shuts down. I checked the amp draw with the two engines and it was about .50 amps. I am thinking the PTCs may be bad, they are marked with the Littlefuse logo, the number 30 and below that u400. I checked the resistance on the PTCs in the circuit and one checked 0 ohms, the second checked 1.8 ohms. I am not sure if the resistance on these can be checked while installed or if they must be removed from the circuit.
Does anybody have this information?
I believe the resistance on a good PTC should be below 5 ohms, is that correct? Any help much appreciated.
If these are bad, what would be the correct part number to replace these?
Thanks
Ray
the PTCs were delivered, I pulled the old ones, installed the replacements, ran on the home layout for several hours with a triple head drawing about 1 amp with no shut downs. I was a little concerned the replacements were about 1/3rd the size of the originals but worked fine. Previously a double drawing .5 amp the power pack would shut down in about 45 seconds. Saved our club having to purchase a replacement power pack.
