Expobar Office Control - Steam issues
I have an Expobar Office Control machine that has started giving me grief when texturing/steaming milk. The steam and hot water wand lose pressure to the extent where nothing comes out of either. They work well for a short time after initially turing the machine on, after it has warmed up, but then for the rest of the day the steam and hot water stop working. If I turn the machine off at the power for around 20seconds and then on again, the red heating light again comes on and the pressure builds up to full steam and hot water again for a period of time, until the whole thing happens all over again.
I have replaced the press-stat thingy (the thing with the black dial that can be adjusted) with a new one and I also replaced the pressure/antivac pin thingy on the top of the boiler with a new one. The boiler element was replaced in the workshop around a year ago as the terminals corroded and were tripping the power.
What else could it be? Is there a relay switch or something that is not clicking on when the steam pressure drops, or is there an overheating switch that is tripping and that re-sets when I turn the power off and on again? Luckily I can still pour shots when this whole steam thing is happening, the group head isn't affected.
I hope someone can help, or point me in the direction of someone I can phone to help, as I live in Tasmania and a long way from the service shop.
Most likely control board I'd think....
There is a relay for the heating element on the control board, which sits behind the touchpad buttons. If the group can still be used when the pressure drops, suspect it's that heater relay intermittently failing rather than the board transformer which is the usual culprit. It's also possible that someone replaced the standard bi-metallic resettable thermal protector switch with a thermostat type switch, but more likely the board. I can source and send you the board, if you can change a pressurestat you can fit the new board. Get in touch if you'd like a quote, alternatively you could perhaps find an electronics repairer to desolder and replace the pcb relay
Well sorry everyone to re-hash this old issue, but I still haven't got to the bottom of it. The problem is still the same as mentioned above. However with further testing and fiddling, I have realised that when the steam and hot water nozzle is not working, the group still operates, however, after time, the water coming out of the group isn't hot.
I have had very patient help from a fantastic repair guy here in Hobart who has again replaced the pressure-stat which didn't work. He also changed the control board with a brand new one, which didn't fix the problem (he put the old one back in again to save me the $). He changed the on-off switch with a new one, he replaced the main plug that goes into the control board, as the old one had a few corroded terminals, again not solving the problem. He also replaced the bi-metallic re-settable thermal protector switch thing on top of the boiler with a new one and I am still getting the problem.
There must be something else to try?? Please, does anyone have any ideas?
The machine still works faultlessly at first, but once it has been sitting around on for a while (maybe a temp related thing??) it faults.
Thanks so much in advance for any suggestions
If your tech can observe the fault then they should also be able to identify the culprit component. It could in theory be any one of the things you've mentioned above that have already been swapped out, you need to find the faulty part with a multimeter measuring for 240V when the fault is occuring to see where the voltage stops. A thermocouple on the boiler would be handy too. The only thing that sounds remotely plausible is that the bimetallic switch has been replaced with the wrong type. The original is a push - button with a 145 degree rating which needs to be manually re-set when it trips. Is it tripping?
Hi, and thanks again for your help.
The bi-metallic switch wasn't tripping before and the fault was occurring prior to the original ones replacement. I think it was a 'well it's worth a try' replacement.
I will show him your reply and see what he thinks.
I wish it was feasible to post it to you for a look.
Sorry for the constant questions but I will not be beaten by this machine!!
We by-passed the bi-metallic switch with a bit of wire and the problem persists. The pressurestat has been replaced twice.
Could there be an issue with some wiring that supplies the boiler? The problem occurs when the machine is warm and has been on for some time. ? Loose connection once it's warm??
Thanks again for your help
Sorry to repeat myself but
I would be looking closely at the heater output from the board and the green multi-pin header. You say the board's been replaced though... Very unlikely to be a wiring fault but we can't rule anything out if the obvious has been eliminated. The only way you'll know for sure is with a meter set to look for AC voltage. When the fault is occuring you should see 0V AC at the element (unless it's the element itself, then you'd still see 240V there), then you just have to move back towards the mains switch one terminal at a time until you find 240V and bingo.
Originally Posted by coffee_machinist
did in you ever end up getting to the bottom of this problem????
i just purchased a second hand expo bar office control this weekend and you guess it, it's doing the same thing you describe. So am wondering how you got it fixed?
I think I got screwed by the bloke I got it from.
I have an Expobar office which I have had for almost 3 yrs and it was almost a year old when I bought it and I would have to say they are bulletproof.
While mine is not a control model the problems will be similar. I have not had to replace any parts in this time.
The 3 problems I have had is 1, the switch below the water reservoir getting wet by not taking enough care while filling the reservoir
2, the pressure/ antivac valve on top of the boiler sticking 3, Air locks in the system (Solved by manually pumping water into the tubes to prime the pump)
Firstly I would clean the pressure/ antivac valve on top of boiler as this costs nothing, Do not lubricate it. Then make sure your water reservoir is full
turn your machine on and listen for the pump priming itself and the boiler. Once this is completed unplug & pull machine apart and look at the silicone tubes for any sign of air in them
if there is air this could be part of your problem. Next prime your machine manually by using a syringe or something similar to pump water into these tubes and force any air out
& make it easier for your machine to prime itself properly when you plug it in again. Reassemble machine and plug in again.
If you still have problems I have marked in bold 2 things below. The pressure controller could be your problem or the first one listed that your electronic switch is not working properly and refilling your boiler. The sentences below are from the Whole Latte Love site i n USA which is quite a useful site. They list the Expobar Office as a Pulser.
You can find a Expobar Office manual online as well. Be careful of replacing too many things as that may give you new problems. If you replace something and it doesnt fix the problem
then it is not the main problem. Good luck.
Multiple Safety Switches and Controls
If the water level in the boiler gets low the electronic controls sense this and turn the pump on to automatically fill the boiler. If the reservoir runs out of water a CPU board will turn off the heating element to prevent overheating. A manual reset high temperature switch is located on top of the boiler as a secondary safety switch.
Boiler Pressure Control
The boiler temperature/pressure is controlled through a professional grade pressure controller. It senses the pressure in the boiler and turns on the heating element in the boiler as the pressure drops.
Tags for this Thread