Pentair EasyTouch surge board

[Telemachus]

Helping a fellow forum member (remotely) look at his malfunctioning Easy Touch surge board. It inadvertently got 24 volts of AC sent through the RS485 from a connected peripheral.

SWG is still getting DC power. There is 4.2v on the input and nothing on the output side of LVO (U3).

I'm pretty sure transiever U2 is toast as pins 5-8 all have continuity with each other. We plan on replacing this.

A few questions for the experts:

1) What voltage should the Red pin be getting on each of the COM ports, if they are connected to nothing but the transformer? My guess is 15v, and this should also be the input to U3.

2) What is the purpose of the PIC24F microcontroller? It appears that newer boards no longer have a microcontroller at all.

3) F1 has no fuse, front or back. Could it be in a middle layer of the PCB?

4) Can the SWG interpret RS485 bus commands independent of this board? In other words, could D+ and D- be removed from the board and connected directly to the RS-485 bus of, say, a raspberry pi? This board would then just be used for power to the SWG.

 

[Telemachus]

21.5V to the top of F1 but nothing to the bottom. Blown fuse? Where is the actual fuse?

 

[Jimrahbe]

T,

The surge card just takes the 24 VAC input from the SWCG transformer and converts it to DC voltage.

The DC voltage going to the cell is about 40 VDC when the cell is not making chlorine and about 35 VDC when the cell is making chlorine. The DC voltage is not too well regulated.

The RS-485 connections are really just a pass-through, the board itself does not use them, it just sends the RS-485 commands to the cell.

The 'fuse' for the card, when it is installed in an EasyTouch, is one of the small breakers in the upper right of the cabinet.

Why not just buy a new card that you will know works? You can always repair the card (maybe) and use it as a spare.

Thanks,

Jim R.

 

[Telemachus]

Already have a working solution. Working on the repair.

In this case, the fuse is connected to nothing. Is the whole bottom half of the board sometimes not used? Perhaps when another part of the system generates the RS-485 signals?

 

[Jimrahbe]

T,

There is just one com port, J20 on the main EasyTouch card.

The three RS-485 connectors on the surge card, just give you additional places to connect things. Anyone of the three can be used to connect J20 to the surge card and the other two make it easier to connect other devices rather than trying to stick too many wires in the same connector.

I know of no other use for the bottom part of the card, but that does not mean one does not exist. Or maybe something planned for the future???

Thanks,

Jim R.

 

[Telemachus]

Thanks. Is there an RS-485 transiever somewhere on the easy touch main board?

 

[Jimrahbe]

Is there an RS-485 transiever somewhere on the easy touch main board?

Yes...

I am not sure what chip, but I'm sure that Tom does.. Calling @ogdento

Thanks,

Jim R.

 

[Telemachus]

From what I can tell, it must be underneath the display.

 

[ogdento]

i'm not exactly sure what the different surge boards all do - i don't have one - but the one in your photo has an rs485 chip on it (U2, a ti SN65HVD485ED), and presumably the pic24 microcontroller sends some signals to the main board... but again I don't know what they are. (maybe somebody could check it with the nodejs pool controller tools?)

anyway, the rs485 chip on the easytouch is under the display (thanks for that, Pentair ). It's likely going to be a max1483esa+ or an isl81483ibz-t... that's what i've always replaced them with but i don't see a reason why the ti part mentioned above wouldn't work either. there's another ti part that has better data input protection but i can't find the number at the moment... it's in a thread here somewhere!

 

[Telemachus]

Thanks.

After replacing the LVO on the surge board and the RS485 chip on the easy touch main board everything is working again.

<$15 repair