Pentair Mastertemp 250 Up Button won't work

[JoeSchmoe]

Hello everyone. First of all, I'd like to say this is a great website. The forums and tutorials have helped me quite a bit in the 3 years we've had our pool.

My question is about the Pentair Mastertemp 250 heater key pad. Last year the up button didn't work, so I couldn't heat the pool beyond 78 degrees. This year, it all worked fine the first day after opening the pool, so I turned the heater down to 68deg until it gets warm enough to swim here in Ontario.

On day two, the heater wouldn't turn on at all. Figuring the membrane key pad was toast, I ordered a new one. With the new keypad, I'm exactly where I was last year. The heater goes on, but the up button doesn't work. It appears from the display, some signal is getting through to the control board, as the screen flickers like it's trying to do something on the up button pushes, but the increases don't take.

I cleaned up all the pins and don't see any damage on the board. Is the board toast? Does someone know the pinout of the membrane connector so I could try jumpering the up button manually? What does that yellow SW1 button do? I'm an Electrical Technologist used to working on the control circuits that run the power grid, so I don't mind getting my hands dirty with this sort of thing.

The official Pentair boards are crazy expensive. How do the aftermarket ones work? I figure the quality can't be too much worse than the Pentair that lasted just 2 years.

Thanks everyone!

 

[ajw22]

Welcome to TFP.

The yellow button is used to reset the maximum temperature setpoint for POOL or SPA.

Many folks have had problems when they tried non-Pentair PCBs.

Lots for you to read in Pentair MasterTemp Heaters - Further Reading

 

[JoeSchmoe]

Welcome to TFP.

The yellow button is used to reset the maximum temperature setpoint for POOL or SPA.

Many folks have had problems when they tried non-Pentair PCBs.

Lots for you to read in Pentair MasterTemp Heaters - Further Reading

Oh man... The Pentair boards are going for $1000 give or take . At around $150 for a non-Pentair I feel like I almost have to take my chances... Especially with other repairs this old house.

 

[JoeSchmoe]

Hi everyone... I thought I'd give an update now that the heater is working again.

I found a pinout on an older post on this forum that said pin 1 to pin 6 is for the up button. So, I removed the membrane keypad ribbon cable (I removed power before unplugging), got my fused leads, and got on the ground to try jumpering pin 1 to 6 to simulate an up button press. My wife watched the keypad while I tapped the pins, and sure enough, the temp went up. Upon further inspection, my earlier attempt at cleaning the pins was not the greatest. Pin 6 was darker than the rest and pretty oxidized.

I shut the power off and cleaned pin 6 with some emory cloth to take as much of the darkness off as I could. Upon reconnecting the cable, the button worked again! Thankfully, I didn't have to buy a new $1000 board. Truthfully, at the price difference, I was going to take my chances with the $150 knockoff.

Shortly after it was up and running, the pool temps started going out of whack... Slowly decreasing while the heat was on. Once again I powered down to check the pins where the water temp signal was coming from (the pair of brown wires). Sure enough, they were darker as well. I cleaned them up with some emery cloth and the temps are holding steady and are seemingly accurate.

Hopefully this experience can help someone else down the road.

 

[ajw22]

I found a pinout on an older post on this forum

Can you post a link to that older post with the pinouts?

 

[JoeSchmoe]

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.

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.

Why did you short the pins? Were the buttons not working? Is the membrane pad connected now?

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

The pins are so small and close together that it's hard to short any two without touching the others. 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. If all pin combinations work by short but not by pad buttons then the membrane is bad.

I would try the membrane pad first and then the control board.

Here's the post.