MiniMax CH heater not working - bad thermocouple?

[merit]

Hi All,
I have an old MiniMax CH 200 pool heater. It worked intermittently last year but this year I'm not getting any heat. The pilot lights and stays lit fine. Looking around on the Internet I've seen several people talk about thermocouples going bad. I cleaned some carbon off it with sandpaper but it didn't make a difference. I've measured the voltage at the terminals where the thermocouple connects to the gas valve and I was getting about 60 mV, I have no idea what it should be though.

Any suggestions of things to look at? Should I consider replacing the thermocouple?

Thanks!

[PoolDoc]

Is this a millivolt heater (no 110V electrical connection) or a powered heater?

[merit]

Is this a millivolt heater (no 110V electrical connection) or a powered heater?

It's a millivolt heater. I found the thermostat's service manual and it says I should have at least 200mv from the pilot generator, so I've ordered a new one. Hopefully that will take care of my issue.

[PoolDoc]

Highly recommend you check the pilot light assembly for deterioration. A damaged flame guide can lower voltage a lot.