Suntouch Automation valves

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PebblePool

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Nov 21, 2016
144
Melbourne, FL
I have a question, I have a Suntouch automation system. And unfortunately two external wires got crossed and shorted. After that all of the valves and relays are measuring 25VDC on my multimeter. I pulled the board and noticed a socketed uln2803a opposite the connectors on the CCA. I removed the uln2803a IC and re-installed the board, after that all of the valves and relays now measure ~0V and my solar valve is closed. If I replace the uln2803a IC would that restore the functionality of my valves and relays? Since the IC is socketed I figure it must be what gets cooked first in the event of an external short circuit.

Thanks!
 
+1 to replacing the 2803, I've seen a bunch of dead ones and they're easier to replace than to test ;)

The single 2803 on the Suntouch drives both the on-board relays (which drive the valves) and any relays that are connected to the 2-pin connectors. The 2-pin connector should measure 24 volts DC only when its relay/aux circuit is ON. On the easytouch/intellitouch the valves are driven by 24 volts AC - not DC - and I think the Suntouch is the same (looking at the 18vac/24vac power connector, the 24vac lines are not converted to DC). The middle pin on the 3-pin valve connector is the "common" pin and only one of the remaining pins should have 24vac.

Tom
 
I ordered the 2803, and you are correct it was 24VAC, not VDC. Which makes sense because they tap voltage from a transformer. I ordered the part from digi-key, 5.03 after tax and shipping. I figure that since it is a socketed part it is the first component to go on the board. I made sure to take a pic of where pin 1 is with my cellphone before removing the 2803. Hopefully that's it.

ogdento said:
+1 to replacing the 2803, I've seen a bunch of dead ones and they're easier to replace than to test ;)

The single 2803 on the Suntouch drives both the on-board relays (which drive the valves) and any relays that are connected to the 2-pin connectors. The 2-pin connector should measure 24 volts DC only when its relay/aux circuit is ON. On the easytouch/intellitouch the valves are driven by 24 volts AC - not DC - and I think the Suntouch is the same (looking at the 18vac/24vac power connector, the 24vac lines are not converted to DC). The middle pin on the 3-pin valve connector is the "common" pin and only one of the remaining pins should have 24vac.

Tom
Click to expand...
 
That's a smart play taking a photo first! If you're ever in doubt there is almost always a small dot or arrow in the silk-screen that denotes where pin 1 should go. If there isn't then the designer screwed up!

Definitely let us know if the new chip solves the problem,

Tom
 
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