Pentair Mastertemp 400 - display not working

[wsdivall]

My Pentair Mastertemp 400 isn't working. There are no lights on the 5-button display.

- No breakers are tripped
- All cables are connected and none have been eaten by squirrels
- No lights showing on the bottom of the control board.
- 1.25 amp fuse is fine
- Transformer reads 24.8 V AC going into transformer and 27.2 V AC coming out of transformer
- I did a bypass to the fireman switch and nothing changed (The bypass works now. I think I had the breaker off when I tried this the first time)
- I replaced thermistor and HLS and nothing changed
- I disconnected the membrane display from the control panel and shorted pins 1 and 2 (closest to the yellow button) and nothing changed
- No burn marks on any boards
- Screenlogic: Pool temp and Spa temp show 107. Outside temp shows 101. It's in the 50s outside

Not sure what to do next... besides replacing either the membrane discplay or control panel... but I wanted to ask the experts first.

 

[JamesW]

Screenlogic: Pool temp and Spa temp show 107.

What is the actual water temp?

What is the set temp?

 

[JamesW]

What is the supply voltage reading?

 

[JamesW]

Transformer reads 24.8 V AC going into transformer and 27.2 V AC coming out of transformer

How are you getting the input voltage?

Those numbers cannot be correct.

https://www.pentair.com/content/dam/extranet/nam/pentair-pool/residential/heaters/mastertemp/manual/mastertemp-heater-manual-english.pdf

 

[wsdivall]

What is the actual water temp?

What is the set temp?

Actual water temp is right at 50 degrees F. Heat is set to 95... but heater doesn't turn on.

I mentioned temp reading on the ScreenLogic app just to show it was obviously not working.

 

[JamesW]

I did a bypass to the fireman switch and nothing changed

The incorrect water temp will prevent the Automation from closing the Fireman's switch, but if you bypassed the switch, then it should work from local control.

Your Transformer Input voltage reading cannot be correct.

Follow the Troubleshooting guide to see what that can tell us.

 

[wsdivall]

What is the supply voltage reading?

I used my multimeter at the breaker that serves the heater and it has a reading of 121.5. I checked all breakers in the pool breaker box and they all read the same. Is that where I check the 'supply voltage' at?

 

[wsdivall]

The incorrect water temp will prevent the Automation from closing the Fireman's switch, but if you bypassed the switch, then it should work from local control.

Your Transformer Input voltage reading cannot be correct.

Follow the Troubleshooting guide to see what that can tell us.

View attachment 624468

OK... let me follow these two troubleshooting guides you provided and get back to you. Thank you.

 

[JamesW]

 

[JamesW]

This is the Fireman's Switch Jumper.

This should be in place for testing to take the Automation out of the equation.

There is also a fuse in the picture that needs to be tested.

 

[JamesW]

In this picture, you can see the yellow jumper removed and the automation connected.

 

[JamesW]

The red arrow points to the junction box where the power is connected.

Test the supply voltage and check the plug that is installed.

The red plug is for a 240 volt supply and the black plug is for a 120 volts supply.

Note: If you install the 120 volt plug with a 240 volt supply, it will seriously damage the heater, so do not change the plug unless you are 100% sure.

 

[JamesW]

The following applies to the five-button keypads on the older MasterTemp heaters. Pin 1 is the common wire. Shorting pins 1 to 2 briefly is the same as pressing "Spa On." Pressing a button on the membrane pad shorts a pin (2 through 5) to pin 1 to make a selection. Pin 1 is the lowest pin, and pin 6 is the highest pin.[40]

• 1 to 2 ...spa on.
• 1 to 3...pool on.
• 1 to 4...heater off.
• 1 to 5...down arrow.
• 1 to 6...up arrow.

You can briefly jump the pins as listed above to simulate pressing a button but don't leave them shorted.

The pins are so small and close together that jumping any two without touching the others is hard. So don't do it if you can't short only two.

If you can short only a single pin to pin one, the board should respond as indicated. If it doesn't, then the control board is bad. The membrane is bad if all pin combinations work by jumping pins but not when pressing the pad buttons.

 

[wsdivall]

The incorrect water temp will prevent the Automation from closing the Fireman's switch, but if you bypassed the switch, then it should work from local control.

Your Transformer Input voltage reading cannot be correct.

Follow the Troubleshooting guide to see what that can tell us.

View attachment 624468

1. Jumper Fireman's Switch at Terminal Board and depress Pool/SPA. YES - Membrane pad comes on with Jumper Fireman's Switch. SPA/POOL displays. Membrane pad doesn't come on unless the Jumper Fireman's Switch is in place.
2. Next step is Check Fireman's Switch Circuit connections (time clock, wiring, external controller relay). Not sure I know how to do this, but I will comb through the user guide you linked for me. Unfortunately, I can't do this yet as I accidentally pulled on my long jumper wire and it blew the fuse. Time to buy new fuse.

 

[wsdivall]

The red arrow points to the junction box where the power is connected.

Test the supply voltage and check the plug that is installed.

The red plug is for a 240 volt supply and the black plug is for a 120 volts supply.

Note: If you install the 120 volt plug with a 240 volt supply, it will seriously damage the heater, so do not change the plug unless you are 100% sure.

View attachment 624480

View attachment 624481

Thank you. I pulled the red/240V plug. It had 220V coming from it.

FWIW - I've had my pool installed since 2019 and this is the first issue.

 

[wsdivall]

The following applies to the five-button keypads on the older MasterTemp heaters. Pin 1 is the common wire. Shorting pins 1 to 2 briefly is the same as pressing "Spa On." Pressing a button on the membrane pad shorts a pin (2 through 5) to pin 1 to make a selection. Pin 1 is the lowest pin, and pin 6 is the highest pin.[40]

• 1 to 2 ...spa on.
• 1 to 3...pool on.
• 1 to 4...heater off.
• 1 to 5...down arrow.
• 1 to 6...up arrow.

You can briefly jump the pins as listed above to simulate pressing a button but don't leave them shorted.

The pins are so small and close together that jumping any two without touching the others is hard. So don't do it if you can't short only two.

If you can short only a single pin to pin one, the board should respond as indicated. If it doesn't, then the control board is bad. The membrane is bad if all pin combinations work by jumping pins but not when pressing the pad buttons.
View attachment 624484

I will try this once I get my new fuse.

 

[ajw22]

I will try this once I get my new fuse.

The fuse for the Fireman’s Switch is a 1.25 Amp 1¼ x ¼” fast blow fuse, which is commonly available.

 

[JamesW]

Screenlogic: Pool temp and Spa temp show 107. Outside temp shows 101. It's in the 50s outside

The problem is the temperature reading.

The Automation won't turn on the heater if the reading is higher than the set point.

Replace the temperature sensors for air and water and then see if it works.

 

[wsdivall]

The fuse for the Fireman’s Switch is a 1.25 Amp 1¼ x ¼” fast blow fuse, which is commonly available.

Thank you so much... I needed that information.

 

[wsdivall]

The problem is the temperature reading.

The Automation won't turn on the heater if the reading is higher than the set point.

Replace the temperature sensors for air and water and then see if it works.

I'm assuming for the EasyTouch and that would be two of the PN: 520272

https://www.amazon.com/Pentair-520272-Temperature-Replacement-Automation/dp/B001DO18FS?ref_=ast_sto_dp