[LGB85]

I am new to the forum. My father brought a P.H. Hobbies, Inc. Model PS3 3 amp pure DC Filtered throttle power supply over today and asked if I could take a look at it and possibly fix it.

I have a multimeter, but I am not sure where I should start to diagnose the issue. We were told at a train show that these units often have diode issues, but I have not confirmed anything yet and was hoping to start from the perspective of the sealed unit before drilling out all of the rivets.

Any help you can provide here would be great. I will post results here as I work through the suggestions.

Forgot to mention that when you plug it in the red light does turn on.

Thank you!

 

[grsman]

Trouble shoot

LGB85
What doesn't work? Do you get anything out of the track terminals? Look for both AC & DC. If so, does it vary with the throttle knob?
Do you get anything out of the accessory terminals?
I don't think PH Hobbies is in business so I don't think it will matter if you drill out the rivets.
Tom

 

[Greg Elmassian]

If it is "pure DC" then it probably uses transistors, makes heat.

It's only 60 VA, if you can use a pulse power unit I'd buy something new, especially since that unit is also only 18v.

Greg

p.s. PH hobbies is indeed long gone, and more to the point, the warranty is definitely expired!

 

[LGB85]

Voltage Readings and Update

LGB85
What doesn't work? Do you get anything out of the track terminals? Look for both AC & DC. If so, does it vary with the throttle knob?
Do you get anything out of the accessory terminals?
I don't think PH Hobbies is in business so I don't think it will matter if you drill out the rivets.
Tom

I appreciate the responses you gentlemen have put together. Here are the readings:

Accessory Terminal Readings (18VAC Listed on the power supply)
AC reading when powered on is 21.76 VAC. 2.0mVAC when off.
DC reading when powered on is 0.001 V DC, . 0 VDC when off.

Track Terminal Readings (Listed as 0-18V on the power supply)
AC reading when powered on is 0.885 VAC regardless of the knob position.
DC reading when powered on is approx. 0.001 V DC regardless of knob position (sign of the reading appears to
change with track direction switch). 0 VDC when off.
I put a train on track and hooked everything up and I cannot seem to get anything which makes sense based on
the readings.

My Dad mentioned that when he last powered it on everything was working fine and then over time the train would slow down. He said someone told him at a train show it could be a diode on these units.

 

[Greg Elmassian]

Well, if you want to proceed, you will have to open it and take and post pictures.

1 diode out would not do it, unless it has a center tap transformer.

The transformer secondary seems fine, and normally the ac is normally also fed to the "input" of the "DC" section.

Greg