Fried controller

[outcastjack]

Being careless with a static grass applicator I think I managed to send the voltage through two sides of a track and damage something in the controller.

 

The symptom is for the controller to now output full voltage regardless of the knob position.

I changed the potentiometer the knob attaches to but it has had no impact on the symptoms.

 

Any thoughts?

 

More importantly is there anyone who repairs DC controllers? 

[DCB]

Being careless with a static grass applicator I think I managed to send the voltage through two sides of a track and damage something in the controller.

 

The symptom is for the controller to now output full voltage regardless of the knob position.

I changed the potentiometer the knob attaches to but it has had no impact on the symptoms.

 

Any thoughts?

 

More importantly is there anyone who repairs DC controllers? 

If you are checking off load voltage 90% of controllers deliver full output voltage to the rails regardless of the controller knob position,  some old H&M Safety Minors, OnTrack and Morley start with low voltage and increase but pretty rare.

 

If locos go like a bat out of hell no matter where the knob is then you have fried something but you need some resistance across the outputs to get a sensible reading.

[polybear]

What make is the controller?  If it's a Gaugemaster they fix 'em for free

[sharris]

My guess is that the high voltage has damaged the output power transistor so that internally it has a collector-emitter short circuit so it's always fully on - if you're lucky you might only have to replace this. That assumes it's a fairly simple controller (e.g. a simple emitter-follower circuit). If it's more complicated (e.g. Pulsed and/or feedback controlled) there may be more parts likely to be damaged.