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Thread: Expobar Office Control with issues!

  1. #1
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    Expobar Office Control with issues!

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi All,

    Couldn't remember my old username/email I used to join so here I am under a new name! My trusty "old" (may 2000) model Office Control recently started playing up (light flashine while pulling shots) indicating reduced flow. so I gave it a de-scale & a good flush. Long story, next morning the machine didn't automatically stop the shot resulting in an extended pull which I stopped manually. Tried re=programming the 2 shot long which resulted in that button no longer working. Later that morning, turned it on to make another round & it no longer heats up. Upon closer inspection, I removed the level sensor wire & nothing, so I'm thinking the board is buggered & possibly the Heating element (tested 47 Ohms across the terminals) too? I called Di Save in Melb & was advised it's the Pressurestat (sounds very unlikely to me but I'm not a Tech).

    What are your thoughts Guys? Any Ideas?

    Micko

  2. #2
    Sir
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    Sounds like there could be a few things going on, unfortunately descaling can sometimes bring out more issues if there is a reasonable build up of scale in the machine. I'd recommend taking it to an experienced tech before ordering yourself a control board.

    The first issue sounds like the flowmeter. The way they work is there is a star shaped wheel thingy (the technical term) which spins and the water flows though and has little magnets on some of the arms, when they whiz past the sensor, it sends a pulse to the control board, the control board cuts off the shot once it has counted the number of pulses that have been set when programing the shot volume. It's not uncommon after a descale for some loose scale to get in there and impede the movement of the wheel (water can still get through without the wheel spinning), meaning no pulses are being sent to the control board, so it doesn't get to the set number of pulses and doesn't stop the shot. When you've tried to reprogram the shot, it's now set to 0 pulses, hence the set point is reached before the shot is started.

    As for the element, most places list the Office as having 2000w element, you should be getting a resistance of around 28.8 Ohms. 47 Ohms would be about right for a 1200w element, so unless it's been replaced by a less powerful element at some point, sounds like you have an issue there too (unfortunately sometimes scale can form on an element and the element work fine until a descale and the scale flakes off). Do you know if it's getting 240v?

    I'd also check the safety thermostat, which cuts power to the element if the machine has overheated,I think it's on top of the boiler for that model and looks something like the pic below. With the machine off and unplugged, use something to push down on the red button, and if it clicks down, that means it's tripped and your machine has overheated, which is often pstat related.
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  3. #3
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    [QUOTE=Sir;647894 It's not uncommon after a descale for some loose scale to get in there and impede the movement of the wheel[/QUOTE]


    Please forgive my ignorance, but can you elaborate how this is possible?

    [QUOTE=As for the element, most places list the Office as having 2000w element, you should be getting a resistance of around 28.8 Ohms. 47 Ohms would be about right for a 1200w element, so unless it's been replaced [/QUOTE]

    I'm pretty sure it's 1200watt, but can't be certain unless I remove it.

    I have been advised by a few 'techs' to start shooting parts at it until it starts wotking (including the control module, element, flowmeter, pstat & autofill valve ) which I simply cannot afford.

    The flowmeter is spotless on the inside, tests 198kohms across terminals(24v) but has a case of the green crusties on the top (so has obviously been wet).

    Interesting to say the least.

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    20190316_183001.jpg just noticed 1200watt on the label, so phew!

  5. #5
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    There's like 4 different faults described in your intial post. Difficult to diagnose when so many things are going wrong.

    If the machine thinks it is low on water (possible as you said there was a flow problem) then it would stop heating. It should be calling for water at this point and the fill solenoid should open and the pump should turn on. If it's not doing this then the best case scenario is that the machine thinks the water tank is empty and won't allow any functions to operate. You mentioned that you removed the level probe and it still didn't try to fill, this would happen in this case.

    If I remember this machine correctly, it has a microswitch under the tank that is actuated by the weight of the water in the tank then opens once the water is low and cuts power to the machine. I've seen these switches fail closed (i.e. won't open and cut power to the machine) but have never seen one fail open. It's possible though, just check it and make sure it's actuating properly. If you have a multimeter, test continuity on the wiring and make sure it is open/closed when actuated.

    If that's all ok then it could be the control box.
    The control box ties all parts of the machine together so it would be a likely fault source to cause so many different things to happen. It may well have started out as one fault then cascaded down to more faults, or, it's just one fault that's causing other parts of the machine to behave improperly.

    I could cover a few other scenarios but it's very difficult to troubleshoot over the internet without the machine in front of me, unless it's a common machine or common fault.

    Give the water tank a try and provide any other information on troubleshooting you have attempted and we'll go from there.

  6. #6
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    Quote Originally Posted by noidle22 View Post
    There's like 4 different faults described in your intial post.

    If I remember this machine correctly, it has a microswitch under the tank that is actuated by the weight of the water in the tank then opens once the water is low and cuts power to the machine. I've seen these switches fail closed (i.e. won't open and cut power to the machine) but have never seen one fail open. It's possible though, just check it and make sure it's actuating properly. If you have a multimeter, test continuity on the wiring and make sure it is open/closed when actuated.

    If that's all ok then it could be the control box.
    The control box ties all parts of the machine together so it would be a likely fault source to cause so many different things to happen. It may well have started out as one fault then cascaded down to more faults, or, it's just one fault that's causing other parts of the machine to behave improperly.
    Yes they certainly do nowadays but as my machine is coming upto 20 years old(next year, serial #345) & I believe a personal import from Spain, it doesn't have this switch(or the later, more powerful 2000w element). All of the wiring tests fine, element works fine when powered directly, pstat continuity is fine, pump works(was replaced in 2014), all solenoids function, but haven't opened up the control box yet to see if I have bad relays etc. To be honest the flowmeter bit & flashing lights has me stuck. I don't know if the flowmeter is bad (I may have to put a scope on it as I believe it to be a hall effect?) but unsure of a good wave/signal to compare.

    I have a Fluke 117 which should be capable of most tests & can report back results.

    Really appreciate the input guys!

    Regards,

    Micko

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    20190316_183136.jpg

    Inside flowmeter

  8. #8
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    20190316_183612.jpg

    Resistance across terminals

  9. #9
    Sir
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    When you do a descale, it doesn't completely break down all the scale, so you get some bits that flake off and can get into unwanted places (flowmeters, gicleurs, solenoids. So if there was some scale that flaked off in the line before the flowmeter, it's possible that it can get in there.
    I've seen the spin of the wheel being impeded on a number of commercial machines before and it behaves exactly as you described (shot not stopping, try to reprogram, followed by no water at all)
    Looks nice and clean, does the wheel in the flowmeter spin freely?And for all the other issues you have going on too, it could be the board, but as noidle22 said, there's seems to be a lot going on and without having the machine there to troubleshoot it's hard to diagnose it all.

  10. #10
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    Hmmm, maybe I'm missing something here. I still don't understand how scale can get into the flowmeter, does the pressure from back flushing force it back through the pump? I was under the impression that the group solenoid dumped it(pressure build up) into the tray?

  11. #11
    Sir
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    It's been a while since I've worked on that model, is the flowmeter before the pump? If so I may have been giving you a bum steer, most machines have the flowmeter after the pump, and with copper piping before it in the water path, which is were you could get the scale from.

  12. #12
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    Quote Originally Posted by Sir View Post
    It's been a while since I've worked on that model, is the flowmeter before the pump? If so I may have been giving you a bum steer, most machines have the flowmeter after the pump, and with copper piping before it in the water path, which is were you could get the scale from.

    Ah ok, now that makes total sense. Yes, the Flowmeter is in between the tank & the pump.

    Well, I have had some progress albeit minute! I managed to borrow the control panel from an Elegance & the machine is alive again, It now heats up & can make coffee(light flashing still) but have to stop it manually. have ordered a Flowmeter. I do remember seeing posts on here about relay issues in the control panel & guys were having dramas finding replacements because of the 18-24 volts range. Does anyone know if there was a fix for this?

    Thanks again guys, help is much appreciated!
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