If you run into a situation where a valve or auxilary circuit on your Pentair pool controller no longer functions at all, don't despair! Assuming the required electrical connections are good, the fault isn't caused by a programming error, and you're trying to control the valve or aux circuit at the outdoor panel (and not using screenlogic or a remote), you may just have a blown relay driver chip... these are cheap and easy to replace.
Aux circuits AND valves are actually controlled by relays which are either on-board, or in the load center. The aux relays are the large-ish 2" x 1.25" Omron devices that are bolted to the load center/enclosure, while the valve relays are the smaller .5 x .25" relays that are soldered onto the outdoor control board (or personality board for Intellitouch).
They're all 24vdc relays, which means 24 volts dc is required to "energize" their coils. The micro-controller cannot safely supply this so it uses a relay driver (the relay driver also protects the micro-controller against back emf when coil is de-energized).
The relay driver is a ULN2803A chip in a 16-pin DIP package, and thankfully Pentair installed these chips in sockets so we can easily pop them out. Easytouch boards have 2 relay driver chips, while Intellitouch boards have 3 (Suntouch boards only have 1):
The drivers can fail open or short - which means they can fail in such a way that the relay coil won't turn on, OR won't turn off. Each driver chip controls 8 outputs and any or all of these outputs could be "dead" - but it's typically not all. Also, if your relay or valve sometimes works and sometimes doesn't, the driver is not a likely culprit (in this case, you should test for a bad relay or bad micro-switches in the valve).
How do I troubleshoot this??
When I encounter a non-working aux circuit or valve, the first thing I do is swap it to another circuit and see if the problem persists. If the swap fixes it I'll undo the swap and plug in a fresh driver chip to see if that does the trick. If you don't have a spare driver kicking around, you can swap one of the other socketed chips - but label them first! Shut off the board power before swapping the chips!
These parts are available at any online electronics dealer, and below is link to the replacement part at Mouser.com (the shipping costs more than the part!):
https://www.mouser.com/ProductDetail/STMicroelectronics/ULN2803A?qs=sGAEpiMZZMvAvBNgSS9LqpP7ived4CP2
Carefully pry the chip out, working both ends using the lightest pressure you can manage. I will frequently <gasp> use an adjacent chip for leverage.
The pins on the replacement chip will likely be spread wider than the socket, in which case you'll have to bend the pins a little closer together...
They sell $$$ pin straighteners for this task, but I like to lie the chip on it's side with the pins against a hard surface, and give it the slightest bend. Then flip the chip over and repeat.
Now you can insert the chip, power up the controller, and re-try your aux circuit or valve. Good luck!
Aux circuits AND valves are actually controlled by relays which are either on-board, or in the load center. The aux relays are the large-ish 2" x 1.25" Omron devices that are bolted to the load center/enclosure, while the valve relays are the smaller .5 x .25" relays that are soldered onto the outdoor control board (or personality board for Intellitouch).
 |
| Valve relays on an Intellitouch personality board |
They're all 24vdc relays, which means 24 volts dc is required to "energize" their coils. The micro-controller cannot safely supply this so it uses a relay driver (the relay driver also protects the micro-controller against back emf when coil is de-energized).
 |
| Omron auxilary circuit relay found in load-center |
The relay driver is a ULN2803A chip in a 16-pin DIP package, and thankfully Pentair installed these chips in sockets so we can easily pop them out. Easytouch boards have 2 relay driver chips, while Intellitouch boards have 3 (Suntouch boards only have 1):
 |
| Two socketed UNL2803A relay driver chips |
The drivers can fail open or short - which means they can fail in such a way that the relay coil won't turn on, OR won't turn off. Each driver chip controls 8 outputs and any or all of these outputs could be "dead" - but it's typically not all. Also, if your relay or valve sometimes works and sometimes doesn't, the driver is not a likely culprit (in this case, you should test for a bad relay or bad micro-switches in the valve).
How do I troubleshoot this??
When I encounter a non-working aux circuit or valve, the first thing I do is swap it to another circuit and see if the problem persists. If the swap fixes it I'll undo the swap and plug in a fresh driver chip to see if that does the trick. If you don't have a spare driver kicking around, you can swap one of the other socketed chips - but label them first! Shut off the board power before swapping the chips!
These parts are available at any online electronics dealer, and below is link to the replacement part at Mouser.com (the shipping costs more than the part!):
https://www.mouser.com/ProductDetail/STMicroelectronics/ULN2803A?qs=sGAEpiMZZMvAvBNgSS9LqpP7ived4CP2
Carefully pry the chip out, working both ends using the lightest pressure you can manage. I will frequently <gasp> use an adjacent chip for leverage.
 |
| If you're going to lever off another chip, be gentle! |
The pins on the replacement chip will likely be spread wider than the socket, in which case you'll have to bend the pins a little closer together...
 |
| The new chip pins are spread too far apart to fit in the socket as-is |
They sell $$$ pin straighteners for this task, but I like to lie the chip on it's side with the pins against a hard surface, and give it the slightest bend. Then flip the chip over and repeat.
 |
| Bending the pins slightly closer together |
Now you can insert the chip, power up the controller, and re-try your aux circuit or valve. Good luck!
I got directed here from TFP, this is a great writeup. Very clear and informative. Call me a boomer, but this is the way the internet used to be - simple HTML layouts, peer-to-peer information about fixing/building/making. Love it!
ReplyDeleteThank you so much for your kind words!
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