Olympia Club pressurestat malfunctioning

Equipment doesn't work? Troubleshooting? If you're handy, members can help.

#1: Post by Tillamook »

1978 Olympia Club used as a daily driver for around 2 years, with original Pstat.
Pstat has worked flawlessly once up to pressure, (boiler light clicks on every 3-5 minutes for about 15 seconds). Recently It started acting funny and randomly turning on and off at odd times, every 30 seconds or so, for only 1 second. Sometimes it will quickly blink 2 or 3 times and then shut off. It continued behaving more and more random, barely keeping the 0.7 bar setting. This morning it completely stopped working.

To be honest I have never understood the technology of these older pressure stats and how they work and why they fail. I have not taken a look at anything yet. I am very confident there are not loose electrical connections. Would I be better off just buying the new updated pressure stat?


#2: Post by Sw1ssdude »

Do you still have the original olympia p-stat? those things are very accurate. but they have a little copper bellow that can leak. if that happens, it would start hissing, and the heat would never be turned off. in there is also a little switch. these things can wear out. they are not exactly a dime a dozen, but close to that, i'd say, 2$.

so the Pstat is basically a copper balloon that inflates and eventually presses against a switch, which breaks the heating circuit. the adjuster screw sets the physical distance of the two components. the further apart, the higher pressure is needed to reach the switch.

(it is good practice to only turn off the machine if the heating is OFF, to reduce the arcing in the main switch, which is absolutely impossible to replace...)

I'd suggest you take off the case (shell? hull?) and turn on the machine. check for hissing from the pstat copper bellow, of for suspicious limescale buildup. if it starts to fail, a MATER pstat is a good replacement.

Next: check the heating light, and if it corresponds with the clicking of the switch (the switch makes audible clicking noises). if the switch is not pressed by the bellow, and the light flickers, the internal switch contact is burnt. time to break out the screwdriver and replacing the switch.

if you can, stick with the original, they are very good, and (usually) very reliable. if you are not too confident with tinkering, keep the original, and install a MATER.

Check my olympia club restoration reports, i documented the pstats there as well.
Lean Mean Caffeine Machine

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#3: Post by jwCrema »

I bought some spare bellows from Migg last time I bought a spring from him. I identified US based source for the microswitch that is used in this marvelous device, but I can't find it right now. I think the manufacturer was Temco, but I am not certain. Migg might have them as well?

I know he does not have any complete, NOS Olympia p-stats.

Tillamook (original poster)

#4: Post by Tillamook (original poster) »

Thank you JWCrema & swissdude. You are both very helpful as usual.

I spoke to soon when I said I am confident the connections are good. There is some corrosion on the contact of the Pstat connecors, that was causing the wire to heat up and melt the connector covers. I am going to clean everything up and make some new wires, and report back.

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#5: Post by jwCrema »

The rest of the story is what helps us all.

About two months ago I had the hot wire between the thermostat and the pstat fail from what I can only describe as corrosion.

I'm not in love with the "hi-temp" spade connectors we buy in the espresso repair section at HomeDepot - they get smokey and black over time with normal use. This isn't the cause of the corrosion but I like wiring handling 11+ AMPs to be in ship shape.

Can you imagine telling the guy in Switzerland who assembled the machine that I'd be griping about the spec of the wire they were using in 2022? Ha!