MasterTemp 400 no display

[Mainiac]

Hi ya'll, long time reader, first time poster, I just need to check my logic with you.

I've got an about 10 year old 5 button MasterTemp 400 with no display, connected to EasyTouch automation (using fireman switch).

I've checked the fireman switch fuse (good), shorted fireman switch (no joy).

Digging deeper I do not find 24v at the control panel, I checked the 24v transformer (at the transformer connectors): Input: 120v Output: 0v (disconnected) Continuity on both primary and secondary windings (why I'm puzzled).

Is the transformer a common point of failure with no other obvious issues/damage?
Is there anything else I should check before replacing the transformer?

Thanks for your thoughts.

 

[1poolman1]

Hi ya'll, long time reader, first time poster, I just need to check my logic with you.

I've got an about 10 year old 5 button MasterTemp 400 with no display, connected to EasyTouch automation (using fireman switch).

I've checked the fireman switch fuse (good), shorted fireman switch (no joy).

Digging deeper I do not find 24v at the control panel, I checked the 24v transformer (at the transformer connectors): Input: 120v Output: 0v (disconnected) Continuity on both primary and secondary windings (why I'm puzzled).

Is the transformer a common point of failure with no other obvious issues/damage?
Is there anything else I should check before replacing the transformer?

Thanks for your thoughts.

Is the system setup to use 120V or 240V? If you lose one leg of 240V, the transformer won't work. Transformers do quit working, but it is rare unless they are subject to a voltage surge or improper voltage.

 

[JamesW]

Continuity on both primary and secondary windings

Can you describe how you tested the primary windings?

How many ohms from white to black?

How many ohms from white to brown?

How many ohms from black to brown?

How many ohms from yellow to blue?

If you put 120 from white to black, you should get 24 volts AC on blue to yellow.

Are you testing the output as AC voltage?

Test each lead for continuity to the transformer case.

 

[JamesW]

 

[Mainiac]

Sorry for the delay in replying, life has ways of getting in the way.

Is the system setup to use 120V or 240V? If you lose one leg of 240V, the transformer won't work. Transformers do quit working, but it is rare unless they are subject to a voltage surge or improper voltage.

120V system. More reply below.

Can you describe how you tested the primary windings?

How many ohms from white to black?

How many ohms from white to brown?

How many ohms from black to brown?

How many ohms from yellow to blue?

If you put 120 from white to black, you should get 24 volts AC on blue to yellow.

Are you testing the output as AC voltage?

Test each lead for continuity to the transformer case.

View attachment 559404

View attachment 559420




View attachment 559422

Tested with Fluke 77, yes looking for AC power, it's a transformer . . .
Primary tested input disconnected at unit wiring harness 120V Black-White 18.8 Ohms White-Brown 73.4 Ohms (transformer input connector, still disconnected).
Secondary tested at transformer output (output disconnected, primary reconnected) 0V, then primary disconnected 1 Ohm Blue-Yellow
Transformer windings to case greater than the fluke reads (no grounds).



Oddly I now have 24V after disconnecting / reconnecting to get the actual resistances vs just continuity, however, still NO lights on the board, now assuming (at normal risk ) the board itself is bad, replacement on order, along with the membrane keypad, found the pair for about $60.
Hopefully that will fix it.

 

[ajw22]

, replacement on order, along with the membrane keypad, found the pair for about $60.
Hopefully that will fix it.

Those are likely not genuine Pentair parts. Many folks have had problems with non-Pentair boards. Good luck but if it does not work then return it.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

 

[JamesW]

You can load test the transformer to verify that it works.

You can use a 24 VAC load at about 20 to 40 watts to see if the transformer powers the device correctly.

For example, you can use (2) 12 volts 20 watt bulbs in series to create a 24 volt 40 watt load.

Verify that the volts are 24 volts and the amperage should be about 1.67 amps.