# Gene Cafe not heating sufficiently



## dadioles

Hello

I have a Gene Cafe 101 that I have been using since 2007 (purchased from Bella Barista) but for the past few months it has struggled to get up to temperature.

It gets used for three or four batches every couple of weeks so has done very well really and until now not required any parts.

Finally the heater packed up (open circuit) so yesterday I replaced the heater (240v) and also the temperature probe that fits at the heater end as it seemed sensible to do so while I was at it.

I cleaned the machine thoroughly including the fan blades and its filter.

When I started it up, the temperature still would not rise above 200 deg C and it only just made that after about 10 mins.

The heater comes on and stays on until the temperature gets to about 160 then it starts to cycle on and off with a typical maximum of about 195 and peaking at 200.

If I try a roast (or should I say 'bake') it will not rise above 200 even after half an hour or more.

If I remove the temperature sensor from the housing at the 'exhaust' end, the heater still cuts in and out limiting itself to about 195. That makes me think that it is the sensor at the heater end which is restricting the temperature. I have not yet tried swapping back the original sensor at that end.

It is very frustrating.

The chaff collector (old type) is a bit knackered but has good air flow. Removing it does not raise the temperature.

The output from the fan is very good so I do not want to replace that if I can help it. What else is there?

I almost wish that I just bought a new one and took the hit. Now after purchasing replacement parts (heater and sensor) it feels like throwing good money after bad but the device is relatively simple so what am I missing?

The chip says 'AC Rev 05 05.28.2007' The transformer on the main board says 'GS-230 230v / 50.60Hz NY 06 07 03' Main Board is '06-01 Rev 02'

I am reasonably technically competent and quite capable of soldering the odd capacitor and using a multimeter (smile).

Help.......

Best wishes and thanks for reading this.


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## DavecUK

Most likely It's cycling below the preset temperature, because the heater box is getting too hot inside and the thermal probe in the heater box, instead of the one at the exit end of the Gene, is making it cycle before the preset temp..

Check everywhere for an airflow problem, especially the gauze under the machine and fan inlet, plus chamber exit and entrance.. If nothing, then the next thing I would consider replacing is the blower fan, as this might be running slower for some reasons age etc..but the problem is almost certainly airflow related.

P.S. With the large Chaff collector split it and clean between the two metal grids....I realise you have removed it, but it's just to give you a little extra to do....every little helps


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## dadioles

Thanks Dave

I agree with your logic and there is only one way to find out.....

A new fan and also a replacement gauze filter and output sensor are on order so I should have an answer within a day or two.

The Gene Cafe has been a super piece of kit and I greatly appreciate the availability of spare parts at not too outrageous prices. I am not aware of anything else on the market which is as effective and at a similar price level.

If this fix works, a replacement chaff collector will be next on the list. That takes me to about halfway to buying a new machine!


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## DavecUK

dadioles said:


> Thanks Dave
> 
> I agree with your logic and there is only one way to find out.....
> 
> A new fan and also a replacement gauze filter and output sensor are on order so I should have an answer within a day or two.
> 
> The Gene Cafe has been a super piece of kit and I greatly appreciate the availability of spare parts at not too outrageous prices. I am not aware of anything else on the market which is as effective and at a similar price level.
> 
> If this fix works, a replacement chaff collector will be next on the list. That takes me to about halfway to buying a new machine!


If none of that works, although I suspect it will (oh and do replace one thing at a time, so we all know the component at fault)....then at least if you buy a new Gene, then you have lots and lots of spares. Also if you have to go down the route of a new one, get one with a 230V element and do the power control modification....it becomes a completely different roaster and also lasts much longer. In stead of modifying a Varilight dimmer, this power controller is now available (wasn't when I did the original mod) and should work without a heat sink. It's also a very good price. You will need to substitute the 487 K ohm supplied potentiometer with a 200 K ohm one, but metal ones are available from ebay for about £1 (link below), you need a linear mono pot. A 200 Kohm one is required as you won't have fine enough control with the supplied one.

http://www.maplin.co.uk/p/kemo-ac-power-control-module-4000va-n85ql

http://www.ebay.co.uk/itm/170703080727?_trksid=p2059210.m2749.l2649&var=470047565989&ssPageName=STRK%3AMEBIDX%3AIT

P.S Won't invalidate your warranty either


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## dadioles

Ok, the last few parts arrived this afternoon but regretfully they do not seem to have fixed my problem

Comparing the new fan with the old fan did not seem to show much difference when I 'felt' the draft. So I removed the old fine gauze filter completely and fitted the new fan. That should now give me optimum air flow. I started the Gene Cafe empty and got the following results.

Temp set for 250 deg, Time set for 20 mins.

Time v Temp deg C

19 = 128

18 = 174

17 = 184

16 = 186

15 = 189

14 = 192

13 = 194

12 = 196

11 = 197

10 = 199

09 = 199

I stopped it there.

Next I changed the output sensor for a new one and repeated the test, it was still warm when I started.

19 = 167

18 = 201

17 = 197

16 = 198

15 = 198

14 = 200

13 = 202

12 = 205

11 = 206

10 = 207

09 = 207

So I have now replaced the heater, the input sensor, the output sensor, the fan and the gauze.

It is still not getting up to temperature!! Aaargh.......


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## dadioles

I forgot to mention, my supply voltage was 241v (the heater is the 240v one).

Current consumption with the heater on was approx 1300w and 16w when the drum was turning but the heater cycled off.


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## DavecUK

You mention the word empty, which makes a difference. *Does the heating element start cycling before the temperature you set?*

If you set the temp to 245 what happens


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## dadioles

Yes, the element switches off at a lower temperature than the one set.

To give you some figures.....

I just switched the machine on from cold and set the 'desired temperature' to 250 deg C and the time to 20 mins.

Everything worked as you would expect and the heater remained constantly on until an indicated temperature of 202 degrees was reached. At that point the heater switched of and the temperature dropped to 196 at which point the heater came on again, cycling on and off every few seconds to maintain a temperature of around 199 degrees. That is with the new parts fitted. It feels as though I need to adjust something somewhere to calibrate the machine.

I have ordered the bits for the power control mod from Maplin and look forward to playing with that. Presumably the mod will completely bypass the circuit which is triggering the relay to switch the heater on and off, in my case at too low a temperature.

I do not know how the existing circuit works but it is as though the sensor in the heater housing should be acting as a cut-off sensor at 250 degrees (for safety) while the sensor at the exhaust end controls the set temperature. If that were the case, the sensor at the heater end is operating about 50 degrees too cool and stopping me from getting above 200. Maybe that temperature is set by a resistor or something on the control board. Unfortunately I am not clever enough to know.

As you specifically mentioned "what happens if you set the temperature to 245?"

I tried that as well. Pretty much the same result. The heater stayed on constantly using between 1310 and 1370 watts until the indicated temperature reached 203 degrees at which point the heater cut out and then cycled on and off to maintain a temperature of around 196 to 199 degrees, too low for roasting.


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## DavecUK

dadioles said:


> Yes, the element switches off at a lower temperature than the one set.
> 
> To give you some figures.....
> 
> I just switched the machine on from cold and set the 'desired temperature' to 250 deg C and the time to 20 mins.
> 
> Everything worked as you would expect and the heater remained constantly on until an indicated temperature of 202 degrees was reached. At that point the heater switched of and the temperature dropped to 196 at which point the heater came on again, cycling on and off every few seconds to maintain a temperature of around 199 degrees. That is with the new parts fitted. It feels as though I need to adjust something somewhere to calibrate the machine.
> 
> I have ordered the bits for the power control mod from Maplin and look forward to playing with that. Presumably the mod will completely bypass the circuit which is triggering the relay to switch the heater on and off, in my case at too low a temperature.
> 
> I do not know how the existing circuit works but it is as though the sensor in the heater housing should be acting as a cut-off sensor at 250 degrees (for safety) while the sensor at the exhaust end controls the set temperature. If that were the case, the sensor at the heater end is operating about 50 degrees too cool and stopping me from getting above 200. Maybe that temperature is set by a resistor or something on the control board. Unfortunately I am not clever enough to know.
> 
> As you specifically mentioned "what happens if you set the temperature to 245?"
> 
> I tried that as well. Pretty much the same result. The heater stayed on constantly using between 1310 and 1370 watts until the indicated temperature reached 203 degrees at which point the heater cut out and then cycled on and off to maintain a temperature of around 196 to 199 degrees, too low for roasting.


The sensor in the heater box should cut out at 250C...even if you do the power control mod, it's not really going to help and if you disable the sensor, you will get a sensor error. Now I actually cannot remember, but I don't believe the probe insertion depth is adjustable on the heater box assembly..... if it is you could try moving it out. It does rather sound like the Motherboard may be defective, as these sensors don't often go wrong and the switching temperature seems to be fairly consistent with that of your old sensor?

Of course your correct, you could put a small resistance on one of the leads and change the value sent back to the motherboard, but without the full tech specs and some very accurate meters, your not really going to know what value to use. The Motherboard are available, but your Gene is so old, it might be best to bite the bullet and get another one and keep everything you have for spares, doing the power control mod on the replacement. See how much a MB is?

If you do decide this, get a 230V Gene to start with and do the power mod on it before you use it.

Of course you could fudge it completely, but moving the sensor right out and plugging the hole in the box...BUT, the problem is you will have absolutely no way of knowing if it's overheating and risk either a fire in the chamber or burnout of the heating element/melting of the Gene. It won't be a matter of if, but when!!

on the bright side you have had 7 years use I suppose, just a bit unlucky as it could well have gone on another 7.....I even wonder if the previous element burning out was related to this problem, as I know how many hours they are rated for and to be honest should outlast the Gene if not abused with emergency stops and the like.


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## DavecUK

In fact I checked my old documentation....the main PCB assembly may not be as much as I feared. Ask BB and in view of the parts you have bought, see if they can do you a deal on a main PCB assembly, or whether they have a used one hanging about. See how much it is and decide if you want to risk it.

I have the service guides and illustrated parts breakdown, if you need them, but I suspect you won't.

Dave


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## dadioles

Hello Dave

Firstly.... I really appreciate your encouragement and support - thank you.

I am convinced that the problem I am experiencing is related to the sensor on the heater housing and its associated control circuitry.

This morning I removed the sensor from the heater housing and left it connected to the main board but dangling so that it remained cool. The machine operated as normal to about 180 degrees after almost 2 minutes of heating and then generated an E4 error - all very logical.

I then tried holding the sensor against the outside of the heater housing so that it would get hot (sore fingers!!) but not as hot as if it were mounted directly in the hot air stream. That seemed to work and the machine operated normally with the temperature being controlled on the display.

I conclude that the sensor on the heater housing has two functions only. One to confirm that the heater is operating and the other, possibly, to cut off the heater if it overheats.

My problem is that I cannot get the temperature above about 200 deg C.

My fix - which seems to work ok - is to remove the sensor from the heater housing and attach it to the outside of the heater housing so that it gets hot, but not too hot. It is hot enough to tell the machine that the heater is working (no E4 error) but probably does not get to 200 deg C which is the point where my heater was being cycled on and off.

Now when I run the coffee roaster the heater will stay on continuously until the preset temperature is reached and at that point the heater cycles on and off maintaining that temperature. If I set the temperature to the maximum of 250 deg C the heater runs continuously until 250 deg is reached and at that point it switches off, the temperature falls back to about 246, the heater comes on again and so - on.

That suggests to me that your power mod would also work ok.

So basically, I will remove the sensor from the heater box and plug the hole. Then glue the sensor to the outside of the heater box so that it gets hot, but not too hot. The temperature will not rise above 250 as that is controlled by the output sensor.

Now to try a roast.....


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## DavecUK

dadioles said:


> I conclude that the sensor on the heater housing has two functions only. One to confirm that the heater is operating and the other, possibly, to cut off the heater if it overheats.


It's primary function is to cut of the heater if the temperature at the measurement point exceeds 250C. The E4 error code is a secondary function and is activated when it doesn't detect a rise in temperature, then the Gene assumes either the sensor, heater or fan is broken.

The one thing I'm worried about is how hot it is getting in the heater box, the other element failed for a reason. If you have a high temperature thermocouple thermometer, it might be an idea to see if it can be inserted far enough to show you the temperature at the original sensors position.

A few tips


Always make sure the heater box is fully sealed with high temperature selant

If you do the power control mod, keep the wattage below 1200W (especially as your not detecting heater box temp), normally 1180 is sufficient for roasting down to 12C and below that perhaps 1200 to 1220 if its really cold.

The exit temperature has absolutely no relation at all to the heater box temp (you cannot extrapolate one from the other)!


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## Javaslinger

Sorry to resurrect an old thread but I have experienced this same issue now on two GeneCafe's. The most recent is quite current with the latest revision of chip and control board. I have replaced both sensors, the motherboard and chip, as well as the power board. Still I am continuing to experience the same issues as the original poster.

I have not replaced the fan, yet, but I'm wary of spending parts to no avail... And now this suggests that is could be the heater getting too hot? Can it get too hot in the heater box with appropriate airflow? I have removed the screen and roasted without the chaff collector entirely - still the same problem of the heater cutting out prematurely. It's not a consistent problem... For example, this last time after replacing the heater thermocouple and the PCB board, I had a perfect roast afterward. Success! I thought... Until the next roast where it was back to it's old issues... it also begins to cut out (I'm a damn American so forgive me...) at anywhere from 451F to max temp 482F...

a


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## BJT

Javaslinger said:


> Sorry to resurrect an old thread but I have experienced this same issue now on two GeneCafe's. The most recent is quite current with the latest revision of chip and control board. I have replaced both sensors, the motherboard and chip, as well as the power board. Still I am continuing to experience the same issues as the original poster.
> 
> I have not replaced the fan, yet, but I'm wary of spending parts to no avail... And now this suggests that is could be the heater getting too hot? Can it get too hot in the heater box with appropriate airflow? I have removed the screen and roasted without the chaff collector entirely - still the same problem of the heater cutting out prematurely. It's not a consistent problem... For example, this last time after replacing the heater thermocouple and the PCB board, I had a perfect roast afterward. Success! I thought... Until the next roast where it was back to it's old issues... it also begins to cut out (I'm a damn American so forgive me...) at anywhere from 451F to max temp 482F...
> 
> a


I've just experienced this issue myself and found a solution (for me at least). I just registered here to let people know in the future if this happens to them. I replaced the heater assembly and sensor and afterwards it would only get to 160 degrees and no more. I since discovered on the official Gene Cafe website the following note for this component:

"IMPORTANT: The new temperature sensors (blue) do not work with older Main PCBs. If the CPU chip on your Main PCB is version 6.1 or earlier, you'll need to replace the Main PCB as well." "http://genecafeusa.com/collections/gene-cafe-parts/products/temperature-sensor-in"

I have version 6.0 so this issue is apparent with me.


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