Greetings, I have a new to me Expobar Office Control manufactured in 2001. It turns on, gets hot, steams when it reaches temperature, but then the temperature drops and doesn't come back on until the machine has cooled, is turned off and turned back on again. I'm just trying to figure out what I need to look for in the repair process. Perhaps of note, none of the automatic dosing tools appear to be set, all the buttons work, and then start flashing after a short period of time above the selection but do not turn off until I press the button again.

My first guess would be the pressurestat.
When mine does this, I tap it with something hard but non-conductive, like a drumstick, and keep it going while I have a replacement on order.
Some versions looked like this:

But I think there is something in the electronics that could also cause this, for which tapping on the pressurestat would have no effect.
-Ed

I had my Alex machine do something very similar to what you're describing. It ended up being the auto-fill control box that was the culprit. On my machine after the heater went out, the pump would not work either. Is this the case for you too?

No, the pump continues to work and cool water will flow from the grouphead. I have not yet investigated the pressurestat, but that does seem to me a likely place to look. Anyone know of a good test for a pressurestat?

You could measure it? The circuit should be open first, then close when correct pressure is reached. After pressure declines, it should open again, but if the pressurestat is stuck, it stays closed. Of course this might depend on the type of the pressurestat.

http://home.surewest.net/frcn/Coffee/pressurestat.html

I've done some testing and have come up with some interesting (to me) results. The machine will stay hot, steam, hot water tap will work indefinitely until I use the group to push water using any of the dose buttons. As soon as water moves through the group, the thermostat kicks off and stays off. Also of note, none of the pre-measured dose buttons actually deliver a measured dose. They must be pushed once for on and once for off. Ideas?

I have had some issues with my Expobar Pulser over the 6 years I have owned it. I purchased it new from WholeLatteLove and have gone to them for troubleshooting. WLL is the big dog distributor of Expobar and probably has the most experience with mechanical issues. Give them a call, their tech support is great!

Bob

Funny, you should mention that, I just got an excellent reply from them today. Will try their tips this weekend. For the sake of others doing searches, from their email:

The most likely cause is the control board. When the machine is fully heated, all of the small connections expand. This can cause a disconnect on the control board which can cause all of the symptoms you are experiencing. It could also be a loose or shorted wire. See the attached diagram. Inspect the inside carefully. Take a look at the green connector on the back of the control board. Carbon build up on this part can also cause the machine to function incorrectly. Use a Q-tip to clean it off.

Otherwise the control board may be bad, and I'll have to replace it.

I'd get some readings with a voltmeter before concluding its the control board.

That means I'd have to teach myself how to use the one I have.