TJ-067 Fan Control Malfunction, Zero Setting Doesn't Turn It Off - Page 2

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
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millcityroasters
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#11: Post by millcityroasters »

zing wrote:I turned the pot stem all the way ccw when I opened the front door,wires look like good,see the attached pic down below.
<image>


From "0" to "60" ,I can heard exhaust motor speed are getting faster and faster,from "60" to "100", I cant heard many different,BUT at "0" the motor never stop running.
Huh. You're right. That doesn't look like it'd cause a problem. Are you certain your knob is tight? That this isn't a mechanical issue with the knob or the way the pot is mounted?

If you can get a voltage off of the fan connection, you should see something around 50 volts as a minimum to move the fan. I'd be interested to hear what your lowest voltage is. If it's high, ask whoever you purchased the roaster from to get you a replacement pot and/or relay?

If it's not the wires, it's the pot of the relay. It is possible for a solid state relay to fail on. I presume a variable solid state relay could also fail partially on.

If you replace the pot, make sure you match the terminals. If you replace the relay, use thermal grease when you mount the relay on the heat sink.

zing (original poster)
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#12: Post by zing (original poster) »

millcityroasters wrote:Huh. You're right. That doesn't look like it'd cause a problem. Are you certain your knob is tight? That this isn't a mechanical issue with the knob or the way the pot is mounted?
Yes,They are tight.
millcityroasters wrote:If you can get a voltage off of the fan connection, you should see something around 50 volts as a minimum to move the fan. I'd be interested to hear what your lowest voltage is. If it's high, ask whoever you purchased the roaster from to get you a replacement pot and/or relay?
How and where can I get a voltage of the fan connection?

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millcityroasters
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#13: Post by millcityroasters »

Can you call or email me direct? You're working with 220 volt power and I'd feel better advising you knowing that you're not going to get into trouble working with a live circuit. I don't mind providing international tech support to North owners, but H-B Home Roasting isn't the place for this discussion.

zing (original poster)
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#14: Post by zing (original poster) replying to millcityroasters »

Yes,Steve.U r right.all discussion here just to help Tj067 keep at its best and improve.

I have done Fan control Mod like what Slickrock did here TJ-067 Fan Control Mod for Precise Control and yes got much better graduated control.BUT at "0" the motor still running like b4.

zing (original poster)
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#15: Post by zing (original poster) »

JK wrote:Steve,
If he has a multi-meter could he test the pot by unplugging power and unplug exhaust fan and touch two leads to both wire on the potentiometer. Then check resistance of OHMs at different setting (1 and 10) on the dial?
After the Fan Control Mod,I tested two leads(02,03) of the pot,I got some information.(plz see the attached pic)

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millcityroasters
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#16: Post by millcityroasters »

zing wrote:After the Fan Control Mod,I tested two leads(02,03) of the pot,I got some information.(plz see the attached pic)
I tested the fan mod myself and briefly discussed it via email with Slickrock. The mod may provide more granularity of control, but I don't think it does much to decrease the minimum air flow. The fan speed on the 1 and 2 kg roasters is controlled by a solid state variable relay that responds to the potentiometer with 0 Ohms corresponding to 100% voltage and something between what you are measuring and 500k Ohms supplying less than the 52 volts (60 hz) required to run the fan at low speed. In other words, at a dial setting of 0, your setup isn't providing enough ohms to drop the voltage far enough to "stop" the fan from running.

Aside from all of this, I'm personally less interested in this mod because we've been experimenting with more airflow as a path to more clean sweetness and greater differentiation of flavors in the cup. This approach requires enough heat to support the increased airflow, but we've got an abundance of heat on tap and in many cases we're getting better coffee.

I'm not making a proclamation here, just mentioning that there's more than one way to do things.

zing (original poster)
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#17: Post by zing (original poster) »

millcityroasters wrote:I tested the fan mod myself and briefly discussed it via email with Slickrock. The mod may provide more granularity of control, but I don't think it does much to decrease the minimum air flow. The fan speed on the 1 and 2 kg roasters is controlled by a solid state variable relay that responds to the potentiometer with 0 Ohms corresponding to 100% voltage and something between what you are measuring and 500k Ohms supplying less than the 52 volts (60 hz) required to run the fan at low speed. In other words, at a dial setting of 0, your setup isn't providing enough ohms to drop the voltage far enough to "stop" the fan from running.
coz on my setup there is too much air flow at 0 setting,I did the fan mod just try to stop fan speed at "0",BUT as you mentioned,it doesnt to decrease the minimum air flow.

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slickrock
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#18: Post by slickrock »

zing wrote: I have done Fan control Mod like what Slickrock did here TJ-067 Fan Control Mod for Precise Control and yes got much better graduated control.BUT at "0" the motor still running like b4.
It's interesting that you attempted the fan mod even though you already had issues with your setup. Still, the mod could be used as a troubleshooting tool for your issue. Perhaps the SSR is current driven instead of voltage-driven (haven't looked it up) and for some reason, there is too much current driving the SSR so the fan is always on. If this is the case, then we need to increase the total resistance So try this:
  • 1. Disconnect the taper resistor so the bias pot and fan pot are still in series alone in the circuit. Doing so will disable the responsiveness of the fan, but that's the least of your problems.
    2. Back out the bias pot to max resistance.
    3. Set fan control to 0, which would be max resistance for the fan pot.
    4. At this point the whole setup should be a about a 1Meg Ohm of resistance with mere micro-amps going the SSR. The fan should be not spinning at this point. If you the fan is still running, then maybe your SSR is faulty.
    5. Slowly trim the bias pot, reducing its resistance until the fan starts.
    6. Back of the trim pot till it comes to a stop. Now, you at least have a setup where the fan can be controlled to full off.
    7. If you achieved step 6, then I would measure the resistance of bias pot and the fan pot in the off position. Tell me what it is, then I can work out potential taper resistors values that could work for you.
millcityroasters wrote: I'm personally less interested in this mod because we've been experimenting with more airflow as a path to more clean sweetness and greater differentiation of flavors in the cup. This approach requires enough heat to support the increased airflow, but we've got an abundance of heat on tap and in many cases we're getting better coffee.
See response here in the mod thread.
07/11/1991, 08/21/2017, 04/08/2024, 08/12/2045

Deano
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#19: Post by Deano »

Hi Zing.

I have the Australian version of the TJ-067 also (from John in Sydney) and my exhaust fan doesn't turn off at zero dial setting either. I've not found it to be a problem.

When would zero exhaust be needed?

Cheers Dean.

jmc
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#20: Post by jmc »

I have the Australian version of the TJ-067 also (from John in Sydney) and my exhaust fan doesn't turn off at zero dial setting either. I've not found it to be a problem.
Same for me
John