Another Z4000 problem.

NortonOGR Forum Member

I have read some of the issues with Z4000s. I have one where the red light is on all the time and the displays never turn on. Outputs are all at zero volts. Breakers don't seem to be open. Fan is on as well as the green light.

I have checked the pots to make sure they are zero ohms when turning on. Mounts seem to be secure with no broken teeth on the gears.

This is my club's transformer and they have sent it to MTH twice for repair. It comes back working but fails after a short time. We have three other Z4000s which all seem to work normally.

Does the display being out indicate anything specific to look for?

My next step is to check the power devices but there seem to be a bunch of them. Any chance of getting a schematic for this?

FWIW my creds are Lionel Service station and nearly 50 years in electronic design.

Pete

11/6/1711:33 AM

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Engineer-JoeOGR Forum Member SUPPORTING MEMBER

The only thing I read so far in a search, is that some times the pots fail and won't turn fully off for power up (handles must be down).

Wouldn't zero ohms mean they are up full?

Sorry Pete. I'm embarrassed to ask! I don't know how the circuit works.

11/6/171:15 PM

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NortonOGR Forum Member

Engineer-Joe posted:
The only thing I read so far in a search, is that some times the pots fail and won't turn fully off for power up (handles must be down).
Wouldn't zero ohms mean they are up full?
Sorry Pete. I'm embarrassed to ask! I don't know how the circuit works.

Joe, A couple of threads mention the pots must be near zero ohms, handles down or the red light will come on. So far its the only thing I have been able to rule out. Seeing how these are built make me a Post War ZW believer. K.I.S.S.

Pete

11/6/171:24 PM

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Engineer-JoeOGR Forum Member SUPPORTING MEMBER

Thanks Pete.

I wonder if anyone will answer this? It seems like the insides of the Z4000 are protected.......(schematics)