Hi all, lots to unpack here but please take a read and let me know what you think.

I have a P700 since new, its about 4.5yrs old now. 1 month ago the brew relay in the Gicar failed, so when you pull the lever, nothing happened. I went about troubleshooting and working out what was wrong, and isolated it to the relay itself (the mini HS1 relay on the board). A replacement gicar is $600 here in Canada, so I would naturally not want to go down that route. I bought replacement relays for about $3 each, and set to just replacing it on the board, that's really basic stuff. This worked great, for 1 week until the relay failed in the opposite manner (closed this time, instead of open), so the pump wouldn't shut off. So out comes the relay and I decide its best to just go full send and use a SSR I have laying around. I remove the bad relay, wire the signal points externally from the relay mounting points and pull power from the mains for the pump. This works perfect, except one strange little thing......If my steam boiler is turned off, the pump activates with the switch and I brew no problem. If I have the steam boiler on, the pump doesn't activate with the switch at all. The pump will still activate to fill the boiler with the steam boiler on, so its clearly something gated. Temporarily I can brew coffee by just turning off the steam boiler, and then turning it back on after pulling my shot but I'm really stumped as to why this behavior exists.....


I'm fully open to suggestions, and I know yah lots would say "just replace the gicar", but its absurdly priced here.

Thanks all!

Maybe replace with mechanical relay one more time and see if the gated behavior repeats? That would tell whether the gated behavior was associated with the use of SSR/wiring or there has been new problems developed when the relay failed the 2nd time.

For sure, I did try that and it does not exhibit the same behavior. Its just so odd, relays are simple devices, signal +/- to close the gate to close another loop, so its so strange to me that me moving the operation outside the Gicar box would alter that.

The HS1 pinout is like this
signal
+ -
| |

| Power in
| Power out


All I did was move the +- to outside the box by soldering to the board, and then moved the power in and out to a different source. My next trouble shoot is to just take the pwer in and out from the board again by the same means I did the signal and see if that makes it work out.......

How about trying having a broken mechanical relay's coil stay in circuit (with its pins for the contacts all cut out)?
I don't have schematic diagrams of the controller module in Pro 700 or that of any dual boiler machines, so I can only hypothesize, that means I could be very wrong, that a gating mechanism does exist, so as to ensure the two boilers would not fire at the same time, and in turn, for the total power consumption to stay within the capacity of a domestic power outlet.

When the machine engages brew process, the brew boiler must fire, that would require the steam boiler to stay off. The two boilers need to lock out one another, and be operating exclusively.

I would then not be surprised if the control logic gates the pump, brew boiler too, with steam boiler status.

When the mechanical relay is replaced with an SSR, a low resistance relay coil is replaced with a much higher resistance device.

Imagine the gating mechanism could involve a relay coil that exhibits certain DC resistance, and such resistance, as well as the current it passes, is read by the controller as part of the input to the interlocking mechanism. A drastic change in that resistance could result in an out-of-range reading, leading to defeat of the mechanism.

Just a thought, that could be wrong.

Schematic diagram, parts list & pictures please.