Group Temp. Sensor Failure

Did you have an issue or question about operation of your plumbed Dream machine on Day One right out of the box? If so, report it here and also keep us abreast of the resolution.
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dbkimmey
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Group Temp. Sensor Failure

Post by dbkimmey » Mon Jan 06, 2014 11:18 pm

FIrst time poster to the group, thank you all for having me. Just received my Dream T today and am getting the group temp sensor failure message. This locks me out of the program screen. Does anyone know if this is a firmware issue, temp sensor, or a possible way for me to remedy this. I will be contacting CCS in the morning but was so excited to have some fresh espresso in the morning. Thank you for your time and assistance.

Ch83
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Re: Group Temp. Sensor Failure

Post by Ch83 » Sat Jan 18, 2014 2:41 pm

What did CCS say? I think the other topic here related to that was getting a new sensor

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chas
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Re: Group Temp. Sensor Failure

Post by chas » Sat Jan 18, 2014 3:03 pm

Yes, definitely let us know the final outcome. Most of the failures so far with this sensor have been with the readings being incorrect high or low. However, this alarm effectively means the sensor is electrically gone - out to lunch - finito!

The Dream uses a port on the back of the group boiler for the temperature sensor, but the port on top of the boiler which was where the sensor was placed in previous models is still there. It is just plugged with a threaded brass Hex nut. I got CCS to send me a spare sensor and I actually installed the other sensor in the alternate location. I then moved the plug back and forth between the two sensors and compared temperature readings in order to see which gave the most accurate and consistent result using a Scace device.

Anyway, what I am getting to with this long winded description is that I tried just unplugging the wire from one sensor and moving it to the other sensor without turning the machine off and this is exactly the error message I got.

The last thing CCS does before they close the machine up for shipping after bench testing is to disconnect the solenoid valves and use high pressure air to blow as much water as possible out of the lines and fittings after draining the boilers. So while the sensor may have failed, it is also possible that they bumped the wire and inadvertently unplugged it while blowing out the water lines.
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goodboyr
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Re: Group Temp. Sensor Failure

Post by goodboyr » Sat Jan 18, 2014 5:21 pm

I'd like to add the results of my investigation to this, and my fix. As many of you have read, I have been going through brew temperature sensors at the rate of about one every 2 or 3 months. I recently had the same symptoms (erratic temperature readings ultimately leading to the temp sensor failure alarm). I initially thought it was a slightly damaged cable, but after carefully examining it, the wires were fine. So, I looked further and finally found the issue on mine. The sensor has a short set of wires, ending in a small black plug that plugs into a cable that goes to the control board behind the front buttons. I disconnected this black plug. It's got a couple of pins on the temperature sensor plug side inserting into the female side. I noted green deposits on both the male and female connector pins and sockets on the copper. Looking at it up close, it appeared to be corrosion. I used an old ham radio trick to clean things up. You mix vinegar with table salt and swish the connectors around in this solution for a few minutes. This completely dissolves the corrosion and cleans the copper. Then you need to dip the connectors into a baking soda solution to neutralize the acid from the vinegar and prevent further corrosion. I used a compressed air can to blow them dry, and reconnected. Temperature reading returned to normal and is rock solid! So, for whatever reason, (I think its the initial blow off of steam when the boiler heats up and closes the vacuum valve) there is enough moisture to cause corrosion. Once it starts, it propagates throughout the connector and causes poor connection, and thus a bad temp reading. To prevent this in the future, I put some silicon grease on the connector to keep moisture out.

So, check the connector and if you see any signs of green deposit on the tiny pins, you may have the same issue.

The reason that a new sensor initially worked for a few months is that its pins are clean and new, and it took a few months of operation for the corrosion to propagate from the female side of the connector on the machine to the male side at the new sensor.
Bob
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goodboyr
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Re: Group Temp. Sensor Failure

Post by goodboyr » Mon Jan 20, 2014 9:25 am

Well, after a few days of working fine, the temperature control deteriorated as it has 4 times before on this machine. As before, the temperature indication for the group gets increasingly erratic, jumping around from as low as 120 to as high as 210 f. Obviously, cleaning the plug connections was not the issue. In previous iterations of this problem, I've replaced the temperature probe, and the problem goes away for a few months and then resurfaces. Next step is to replace the three items in the temp control system: The cable, the temperature sensor and the control board. Will report back if and when this happens.
Bob
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Ch83
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Re: Group Temp. Sensor Failure

Post by Ch83 » Mon Jan 20, 2014 9:30 am

Thanks for keeping us updated on the matter

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Re: Group Temp. Sensor Failure

Post by goodboyr » Thu Jan 23, 2014 2:22 pm

I've received a new temperature sensor, it looks a bit different from the previous ones. Colour is brass now instead of silver, same size, code on white sheath is now "51/2013", probably a date code of some sort. Waiting for new cable and control board to arrive.
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chas
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Re: Group Temp. Sensor Failure

Post by chas » Thu Jan 23, 2014 3:33 pm

Typically date codes like that mean 51st week of 2013 which is only a month ago. No way did that get manufactured, shipped to Milan, then to New York, clear customs, get to CCS, and ship to you in a month. I am guessing CCS just ordered a compatible batch of sensors directly from a US supplier. That's what they ended up doing with a "stainless steel" spring that kept rusting on the Tank models.

It's wise - though hard - to wait for the new cable and board to arrive. For all you know a defect in the control board was taking out the sensors.

After removing the back "door' from my Dream front panel module and not seeing evidence of what they did about the humidity issue, I asked CCS tech TIm about it. I thought they had sprayed Polyurethane on the boards and they obviously hadn't. Apparently the "fix" consists of a sheet of acetate that is glued to the back of the LCD board. That isn't visible without more disassembly that I care to do at this time so I'll take their word for it.

One thing I was glad to see due to my recent GS/3 experience is that the Dream has a socketed RTC battery that is easily accessible when it goes bad many years down the road. My GS/3's RTC battery went belly up in 4-5 years. It is soldered to the control board and under a layer of many wires. Fortunately, they do make a vertical socket so I have one of those on order. Since I am going to all this trouble the next battery will probably last the life of the machine unless I hang on to it for 20 years, but I can live with that!
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Re: Group Temp. Sensor Failure

Post by goodboyr » Thu Jan 23, 2014 3:45 pm

Agreed. Hard to look at the dead machine on the counter. My guess is that as you say, the control board was part of the problem. According to CCS who spoke to LA Spaz in Italy about my situation they felt it was a faulty board too. As for the sensor, the printing is identical in terms of font and location. Hard to believe a US supplier would duplicate that.
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Re: Group Temp. Sensor Failure

Post by chas » Thu Jan 23, 2014 3:52 pm

Perhaps I should've said a US distributor

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Re: Group Temp. Sensor Failure

Post by goodboyr » Thu Jan 23, 2014 4:26 pm

Lol. I'm too literal! That why I'm an engineer.
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Re: Group Temp. Sensor Failure

Post by goodboyr » Fri Jan 24, 2014 10:47 am

Plus I can't read. The sensor labelling is "51/2012". Duh!!!
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Re: Group Temp. Sensor Failure

Post by chas » Fri Jan 24, 2014 11:07 am

Oh an old "shop worn" sensor then ;-)

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Re: Group Temp. Sensor Failure

Post by goodboyr » Fri Jan 31, 2014 5:25 pm

CCS shipped me a new cable, sensor and logic board. The new board came right from La Spaz in Italy. Looks exactly like my old board. No sign of any waterproof coating. After uploading firmware to 1.19, and re entering settings, my baby is up and running. All looks and tastes good. Absolutely fantastic support from Tim at CCS. Let's hope thats the end of my mystery problem with temperature control. I will add pictures showing old and new board and old and new sensors on the weekend.
Bob
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Re: Group Temp. Sensor Failure

Post by Ch83 » Fri Jan 31, 2014 5:58 pm

Great I would like to see those. Also congrats on the repair. Hope thats the end of it

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Re: Group Temp. Sensor Failure

Post by goodboyr » Sat Feb 01, 2014 1:15 pm

Its working great. Seems like the temperature control is more stable. With the old board and sensor, if you did a pre shot warmup with an empty PF, the indicated temp would overshoot by at least 8 deg f. Now, the temp just nicely returns to the setpoint with minimal overshoot. Back to the great La Spaz consistent shot quality every time.

Here's some pictures of the control board. Note that there is a button board (the front of which is the surface that forms the touchpad). This board has a single ribbon cable that connects to the logic board. I only swapped out the logic board. The old and new logic boards are exactly the same, except for the date code.
I've also annotated a shot of the board with the connections labelled, because some of the connectors are the same, and if you ever change one out, if you don't keep track you could plug the wrong one in.
The board has two dip switches. For Dream models, both dip switches need to be set to the Off position. For Dream T switch 1 is set to on, switch 2 is set to off.
Please excuse my hand drawn letters on the picture!

First shot is the display side of the two boards, old on right.

Image

Here's the other side, with the connections and dip switches. Identical.

Image

Here's the connections labelled: (The black connector that's oriented on the side...you cant see the pins, labelled M1 on the board is where the button panel plugs into)

A - Ribbon cable to card reader
B - Ribbon cable to power and relay box (black box at bottom right of machine)
C - Boiler and group temperature sensors
D - Boiler level sensor
E - Barista LED lights
F - Not used (My suspicion is that's where you plug the MAT sensor)

Image
Bob
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chas
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Re: Group Temp. Sensor Failure

Post by chas » Sat Feb 01, 2014 4:52 pm

According to Tim at Chris Coffee the board "fix" they did was to glue a thin sheet of acetate over the back of the LCD module board. As far as I know this was NOT done to both boards.

Since you only show the front side of each board in your photos I couldn't see for sure if yours had the fix. Could you tell?

Thanks for those photos by the way. I popped that back cover off the front panel enclosure box last week and took some photos of mine but yours is much better since it is out of the unit with all the cables detached.
Chas
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Re: Group Temp. Sensor Failure

Post by goodboyr » Sat Feb 01, 2014 7:17 pm

Chas. You must be talking about the other panel which has the buttons in it. This one has the LCD panel (you can see it in the first picture). The other panel with the buttons has a clear window where the display panel can be seen through. I only changed out this panel.
Bob
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