Large Scale Central

Starr-Tec Hogger

General Discussion
#1

Does anyone know what is used inside the powerpack to change polarity? My engines run in one direction, but when the reversing switch is thrown on the hand controller the engine barely moves in the opposite direction. I know the switch on the controller only activates something inside the powerpack because the controller is connected to the powerpack with a phone cord which couldn’t handle the amperage of a large scale train. Must be some kind of solonoid or electrical circuit. Thanks…Jerry

#2

Dear Jerry,

If you don’t hear a relay click when changing direction, it most likely uses transistors.

Simplified explanation:

Two (higher current output) transistors are hooked up in a complementary circuit.

Drive their (low current) shared inputs positive, the positive output transistor conducts, while the negative output transistor shuts off.

Drive their shared inputs negative, the negative output transistor conducts, while the positive output transistor shuts off.

Hope this helps.

Sincerely,

Joe Satnik

If the circuit is as I described, I’d guess that your negative output (for reverse direction) transistor has gone bad. (Note “if”, and “guess”.)

Edit: added guess to end

#3

Thanks. Since we are in to " if & Guess" Do you think a relative novice could find & replace the offending transistor? Haven’t taken it apart yet, but assume everything is on a pc board. Thanks again…Jerry

#4

Probably not.
However, just to be sure, have you disconnected from the rails, and connected directly to the loco wheels?
On track power, sometimes a reverse power can load through a directional device, like, oh, diodes for markers, or even diodes in a reverse loop.
Just to make sure.

That said, I’ve fixed a lot of power supplies in my time.
If riveted, drill 'em out.
See what’s there.
I often draw a schematic of what I see so I know how the circuit is laid out.

#5

Or, is this one locomotive or all of them?
No other power packs connected elsewhere (like a yard) where a failed insulated joiner can cause exactly this?

#6
Curmudgeon said:
Or, is this one locomotive or all of them? No other power packs connected elsewhere (like a yard) where a failed insulated joiner can cause exactly this?
I did the basic trouble shooting. Changing out locos, substituting new phone line etc. Fortunately the MRC 20 that I have operates correctly, so I can continue to operate. I will drill out the rivets & maybe something obvious will show up. Thanks, Jerry
#7

The old Star-Tec hoggers are basically a not very well done attempt to copy the excellent MRC C20.
The basic idea is the same and the Hogger uses a relay for direction change.

#8
TonyWalsham said:
The old Star-Tec hoggers are basically a not very well done attempt to copy the excellent MRC C20. The basic idea is the same and the Hogger uses a relay for direction change.
If it does use a relay, then maybe the contacts are dirty & could be cleaned, or is it a sealed unit? Maybe I could substitute any small 12-16 volt relay? Dont know how much worse it could be than the MRC, had that back 2 times for repair. Jerry
#9

Sorry Jerry I don’t know how to fix it.
My experience with Star-Tec equipment was limited to picking it up and throwing it away.

I have had a C20 ever since they first came out years ago. Even though it is a 110 volt system it is my track test controller. I power it with a step down transformer (240v - 120v) and it has never ever given me any trouble. At one stage I made an R/C adaptor for it which is now useless to market because, with the next generation MRC changed the way it works.