I have an interesting issue with a T3 controller. Upon startup or after sittng idle, on a multi-floor run in the up direction I will get the TF LED on the REG card. The REG LED glows faintly then the TF LED comes on. My DF relay also drops out which gives me error code 24 (drive fault). Car then slows to correction run into next landing. Error code 24 is the only fault I'm getting. After a couple runs problem seems to go away. Only happens on a multi-floor run in the up direction. Since the problem goes away as things heat up, it seems like a component issue to me. Just having trouble nailing this one down. Any info will be greatly appreciated! Thanks in advance.

I'd clean the tach, brushes, etc, clean the card edges and do the tach adjustment procedure in the manual and set the tach pot so the speeds are right on. If it continues after that you might want to try a board. Is it MG?

I have cleaned the tach and the tach brushes look good. Haven't done the tach adjustment yet. Will definately try that. It is MG. Thanks for your response.

This TIII is it a Micro Modernizer or a true TIII made by Dover? The Micro Modernizer was made by swift and sold to Dover and is a little different.

I think it is a true T3 to the best of my knowledge. Is there any way to tell for sure?

Micro Modernizer is written on the top of the controller.

It's true Dover TIII then.

Sounds like something is wrong with your tracking for sure. Could even be an SCR in the Generator Field Control. The ribbon cable on reg board goes back to another board with several pico fuses on it to fire the scr's. If no monitoring system, log in and try the command "VEL". It should show dictated and actual speed. The difference is what is lighting the TF light.