Our Visacrem V6 / Gaggia G6 is overfilling. Either it reaches its timeout and all lights start blinking, or it manages to overfill to the point of water/steam coming out of the safety valve. To solve it, I acid treated the boiler and level probe. Seemed to work fine when I was on-site. A few days later, the employees complained again. What could be the problem? I was thinking PCB (dry capacitor, wrong voltage levels, etc.). But I don't have a schematic for the PCB in the control box, so I can't problem solve it without investing a lot of time.
Sounds like a controller or wire connection. Make sure the boiler ground is good. And ohm from the boiler to the controller ground. As Chassis age they get corrosion inside the mounts from cleaning chemicals. The other thing is the pump relay may be hanging intermittently.
I'm heading over there now. I'll of course ohm the ground (boiler->pcb), and probably bring a cable to ground it extra, just in case. Any last minute tips for other things too look for?
I see you said pump relay, but I don't think that would cause the auto-fill timeout alarm (all LEDs flash)? That means the PCB itself is engaging auto-fill, but times out? Not a hanging relay? How else would the PCB know the relay is stuck on?
I think I narrowed it down to the pump head. I removed the rear panel and the motor couldn't move. Quickly turning off and on the water supply valve, made it “break free”, so it was perhaps just slightly seized. However, it sounds like it doesn't dispense water into the machine. Either one of the connections are clogged with limescale or the pump simply can't supply? And one of the connectors is a restrictor right? Which could be more prone to limescale buildup. Turning the manual water valve fills the machine very fast, and it works fine. Just until next time water level drops too low again.
Sorry, but I keyed into the overfilling part of your post. But getting low on water and popping off the safety is another whole problem. What design is the boiler temp control? Pressure switch or temp sensing? PID's are used on double boiler machines to keep brew temps at a accurate level. Pressure sensing on steam boilers with heat exchanger brewing. But there are always odd balls out there. If it's popping the safety, the pressure switch is likely to be the problem. I've had to replace a lot of them. Still have a whole box full of marginal ones that work fine for a few days then hang after heat saturation. The light duty ones don't like minerals. And the heavy-duty ones are noisy and have a wider range.
I think the problem was dual, along with user error. First time I fixed it, it was poor PCB<->ground or level sensor contact and/or limescale build-up in the boiler, which caused it to auto-fill, even when the level was sufficient. The waiters powering it off and on again several times (to reset the timeout error), completely filled the boiler to the point of water coming out of the safety valve. This of course caused a lot of steam as the boiler surface was very hot (so I don't think it was overheating). It has a Sirai pressostat. Second problem was poor pump delivery, which caused the auto-fill to never reach the level.
I can't say for sure I have figured it out, until I descale everything in the boiler-fill circuit including the pump head, and dismantle the pump head and lube it if it moves slowly (or replace the entire head).
I just noticed the plumber have it plumbed into the hot water line (>10 years ago). This has probably done some damage to the pump head over time.
Hot water input would definitely cause a problem with the pump over time. Mainly the bearing lubrication would dry out. Highly recommend a new pump head. Also hot water often will contain small particles of scale that the pump tolerances will not accommodate.