Author Topic: JBC Soldering Station CD-2BC - Complete Schematic & Analysis  (Read 5100 times)

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Offline johnmx

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I want to create a controller for the JBC T245 handle, but first I decided to see how the original controller works. Therefore, I had to reverse engineer the circuit of a CD-2BC model.  :-/O
In order to understand the following analysis it is necessary to follow the schematic of the attached pdf. I also added some LTspice simulations.

Starting at page 1, the power rating of the main transformer (80 VA) is based on its size. I do not know the real value. There is some type of temperature sensor built in the transformer. At first, I thought it was a 33 kΩ PTC (measured with a multimeter in open circuit). Latter I discovered it could not be, because when the circuit is powered the sensor resistance is only around 1.65 kΩ @ 23 °C and 1.92 kΩ @ 43.5 °C. If anyone knows what type of sensor could be, let me know.

The interface board has nothing special about it, just the handle connector and an isolated serial to USB converter.

Jumping to page 2, here is where the most interesting circuit is.
The AC voltage used to power the solder iron is controlled by a pair of MOSFET transistors. Diode BAS16 charges a tank capacitor and this voltage is limited to 18 V by a zener in parallel. The top optocoupler turns ON the FETs and the bottom one discharges the gates for a fast turn OFF. The ~V23 voltage is around 31 Vp when the driver is OFF and 26 Vp during ON (peak values). The driver is always turned off for around 308 us on every half cycle during zero crossing.

Moving to the right, there is a differential amplifier measuring the voltage drop on the 5 mΩ shunt resistor. The voltage gain is set to -22.65 V/V and the output voltage is shifted by 1.65 V of offset (Vcc/2). Although the measured tip current is around ±10 Ap, the circuit is able to measure up to ±14.4 A maximum.
There are two sleep detect signals, one for the tip exchange holder and another one for the handle holder. The tip shorts these signals to ground. SLP+ comes from an output pin of the dsPIC and it is always at +3.3 V.

Next, there is the amplifier circuit for the temperature measurement. The total amplification gain is -244.6 V/V. This signal, T_TIP, is invalid when the output driver is ON, saturating above Vcc during negative cycles and below ground during positive cycles. Analog switches controls what signals feed the differential amplifier. When SW1 and SW2 are ‘0’, T_TIP represents the temperature by measuring the small voltage between TC and COM. The circuit is at this state most of the time. One time during power up and one more when the handle is connected, the circuit changes SW2 to ‘1’ during 30 ms. At this point, both inputs are connected to TC. Maybe this is used to see the offset of the amplifiers. Sometimes, especially when the tip temperature decreases, SW1 goes to ‘1’ for 300 us up to 8 ms. Now the amplifiers are measuring between LOAD and COM, this is the voltage drop at the heater. I do not know what they are trying to do here, because they do this when the output driver is ON. When this happens, T_TIP is saturated and remains like that for the complete cycle.
When the driver is OFF, T_TIP represents the tip temperature. There is more than 200 us for the dsPIC ADC to sample the temperature between every half cycle. I have notice that this signal seems stable inside this window but it is different depending if the previous cycle was positive or negative, one is always higher than the other for more than 100 mV @ 300 °C! Also there is a lot of ripple outside of this window when the driver is OFF. See attached pictures “T_TIP@300ºC”.
I think they detect when the handle (and the tip) is connected by analyzing the signal T_TIP.

Moving on, the optocoupler controlled by the signal ISO1 does nothing on this unit.

Next, there is a circuit to detect when the output voltage is applied. I called the signal DET and it is active low. It goes to the active state every time the output driver is ON. I removed the 470 kΩ resistor forcing the DET to be always inactive. The behavior of the station was very strange, the maximum output power was limited to around 10% and, with a setpoint of 300 °C, it heated the tip to only around 100 °C still showing 300 °C on the LCD.

Next, we find the ESD safe circuit. TC is connected to mains earth through a couple of 0.22 Ω resistors and a 1.25 A fuse. If the user tries to solder a live circuit with reference to mains earth, it may happen to blow the fuse. This fuse is SMD and not easily replaceable. The 1 MΩ resistor ensures that the iron will still be ESD safe after such event. There is another differential amplifier measuring the leakage current between the iron tip and earth. The total voltage gain is -829.5 V/V, which ensures a correct measurement range of ±9 mA.

Finally, there is the power supply circuit that generates +8 V, +4.9 V, +3.3 V and -4.5 V.

On the last page, one can find the dsPIC connections, LCD, external I2C EEPROM, buttons, internal jumpers, ICSP connector (before you ask, yes the program is read protected!), a temperature sensor MCP9701, buzzer and the zero cross detection circuit. Since the thermocouple cold junction is at the handle, not in the control unit, it is not necessary to measure the unit internal temperature. However, they do it for some reason. This temperature will be significantly high because of the main transformer (main source of heat).
Zero cross detection is done in a very simple way. The signal is active some time before the zero cross event and the value of this time depends if the previous cycle was positive or negative. Not perfect, but I guess it is more than enough for the specific application.
All of this can be verified in LTspice using the supplied files.
Best regards,
johnmx
 

Offline Gandalf_Sr

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Re: JBC Soldering Station CD-2BC - Complete Schematic & Analysis
« Reply #1 on: June 29, 2019, 11:11:22 am »
Great analysis John.  I have been thinking about something similar - I bought the $200 Jabe UD-1200 that looks like a copy of the JBC from the outside (not sure about inside).  Are you planning on doing the hardware and the software?  Are you thinking of changing the processor?
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Offline Hydron

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Re: JBC Soldering Station CD-2BC - Complete Schematic & Analysis
« Reply #2 on: June 29, 2019, 12:55:14 pm »
Thanks for your work - I'm toying with the idea of making a DIY station myself so it's very useful to have the original schematic as a reference.
 

Offline Cliff Matthews

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Re: JBC Soldering Station CD-2BC - Complete Schematic & Analysis
« Reply #3 on: June 29, 2019, 01:21:03 pm »
..I bought the $200 Jabe UD-1200..
Meh.. supporting off-shore copycats, I don't understand not buying ADS200 for ~ the same $. In the long run, it's got top-tier support, better quality, a durable and economical tip eco-system with hot tweezer's available in a few weeks :-//
 

Offline 2N3055

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Re: JBC Soldering Station CD-2BC - Complete Schematic & Analysis
« Reply #4 on: June 29, 2019, 02:21:55 pm »
..I bought the $200 Jabe UD-1200..
Meh.. supporting off-shore copycats, I don't understand not buying ADS200 for ~ the same $. In the long run, it's got top-tier support, better quality, a durable and economical tip eco-system with hot tweezer's available in a few weeks :-//

I agree.. If you can buy half decent chinese noname station that solders just fine for less than 100 USD then it's a good deal.
For 200 USD, for a bit more ADS200 gives you JBC performance and good production quality tool... And their tips are cheap..
 

Offline Ribster

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Re: JBC Soldering Station CD-2BC - Complete Schematic & Analysis
« Reply #5 on: June 29, 2019, 04:27:43 pm »
Thanks for your work - I'm toying with the idea of making a DIY station myself so it's very useful to have the original schematic as a reference.

I am designing one that works on USB C.
One that works with the T210, T245 tips and also a version with the micro tweezers.
Have a prototype PCB designed, but mostly working on my pick and place at the moment.
So will not be finished for the next year. Plan is to design and make the PCBs and sell them in a webshop.
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Design of hardware, software with stm32 and prototyping.
 

Offline Gandalf_Sr

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Re: JBC Soldering Station CD-2BC - Complete Schematic & Analysis
« Reply #6 on: June 29, 2019, 04:39:20 pm »
I wasn't aware of the existence of the ADS200. The Jabe UD-1200 works OK and I have 2 KSGER T12 systems plus a dozen or so T12 tips. I also have a a Hakko FX-951.

The OP was discussing a design for a controller for the T245 handle; I believe my UD-1200 is compatible with that handle hence my interest.
If at first you don't succeed, get a bigger hammer
 

Offline Ribster

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Re: JBC Soldering Station CD-2BC - Complete Schematic & Analysis
« Reply #7 on: June 29, 2019, 05:04:17 pm »
The wiring for the T210 and T245 is quite the same.
Here you can find the pinout. Ok it's on an other forum, but i wanted to give credit to the actual poster ;)
http://dangerousprototypes.com/forum/viewtopic.php?f=56&t=7218&start=1140#p66362
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Offline simxdx

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Re: JBC Soldering Station CD-2BC - Complete Schematic & Analysis
« Reply #8 on: July 29, 2019, 02:38:31 pm »
Good job! :-+
 

Offline MSS

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Re: JBC Soldering Station CD-2BC - Complete Schematic & Analysis
« Reply #9 on: November 01, 2019, 12:59:26 pm »
I want to create a controller for the JBC T245 handle, but first I decided to see how the original controller works. Therefore, I had to reverse engineer the circuit of a CD-2BC model.  :-/O
In order to understand the following analysis it is necessary to follow the schematic of the attached pdf. I also added some LTspice simulations.
Thank you very much for your job!
I'm working on similar task and was looking for the schematics. I need to support T210, T245, DR560 and some ERSA tools.  So currently i have reference schematics for JBC=)
 

Offline Icchan

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Re: JBC Soldering Station CD-2BC - Complete Schematic & Analysis
« Reply #10 on: January 22, 2020, 03:16:01 am »
I was looking through the schematics and I went over the ZCD and I just can't understand how it prevents the lower transistor from having Veb breakdown since lower transistor sees negative voltages in excess of -23.5v on the negative half cycle...
Unless there's something I missed?

Since both 23.5v and 12v secondaries have common ground, the AC voltage is swinging between +23.5v and -23.5v in respects to GND... right? :D

It's late at night... I might be overlooking something obvious here.

This seems like a learning opportunity if anyone cares to explain to me what I'm missing here ;D

Offline shangaoren

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Re: JBC Soldering Station CD-2BC - Complete Schematic & Analysis
« Reply #11 on: March 09, 2020, 10:12:50 am »
there is something i don't get in your schematics of reverse engineering :

i have two tips, one that seems to have the heater fried and the other that works. i tried to put both in hot water, measured voltage and resistance between every pins and this is what i get.

As i understand the results, the common is the tip body, heater is between body and middle pin and thermocouple is between first pin and body, did i miss something ? 
 

Offline johnmx

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Re: JBC Soldering Station CD-2BC - Complete Schematic & Analysis
« Reply #12 on: March 09, 2020, 10:53:37 am »
there is something i don't get in your schematics of reverse engineering :

i have two tips, one that seems to have the heater fried and the other that works. i tried to put both in hot water, measured voltage and resistance between every pins and this is what i get.

As i understand the results, the common is the tip body, heater is between body and middle pin and thermocouple is between first pin and body, did i miss something ? 
Are you using a T245?
Other types may have different connections.

A picture is worth a thousand words (see attached).

Best regards,
johnmx
 

Offline shangaoren

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Re: JBC Soldering Station CD-2BC - Complete Schematic & Analysis
« Reply #13 on: March 09, 2020, 11:13:01 am »
Yes, the broken one is a C245-789 and the other one is a c245-911
 

Offline johnmx

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Re: JBC Soldering Station CD-2BC - Complete Schematic & Analysis
« Reply #14 on: March 09, 2020, 11:56:37 am »
Yes, the broken one is a C245-789 and the other one is a c245-911
As you can see from the attached picture on my last post, C3 is the common, C2 the heater and C1 the thermocouple.
Best regards,
johnmx
 

Offline shangaoren

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Re: JBC Soldering Station CD-2BC - Complete Schematic & Analysis
« Reply #15 on: March 09, 2020, 01:01:04 pm »
sorry, your picture does not help me a lot to understand why i get this measures ^^'
 

Offline leo938

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Re: JBC Soldering Station CD-2BC - Complete Schematic & Analysis
« Reply #16 on: June 08, 2020, 09:46:54 pm »
John,

Many thanks for the detailed analysis, must have taken some time.

I have a similar station & was interested in trying to get it to trigger a fume extractor automatically when in use. I see in your analysis that you mention

Quote
Moving on, the optocoupler controlled by the signal ISO1 does nothing on this unit.

I wonder if you can recall was this signal triggered by the iron being removed & returned to the station? If so it seems like one possible use for such an optocoupler setup like this & could be a simple way of implementation an automated fume extraction system.


Anyway thanks again for your analysis!
 

Offline johnmx

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Re: JBC Soldering Station CD-2BC - Complete Schematic & Analysis
« Reply #17 on: June 08, 2020, 10:55:26 pm »
John,

Many thanks for the detailed analysis, must have taken some time.

I have a similar station & was interested in trying to get it to trigger a fume extractor automatically when in use. I see in your analysis that you mention

Quote
Moving on, the optocoupler controlled by the signal ISO1 does nothing on this unit.

I wonder if you can recall was this signal triggered by the iron being removed & returned to the station? If so it seems like one possible use for such an optocoupler setup like this & could be a simple way of implementation an automated fume extraction system.


Anyway thanks again for your analysis!
Hi Leo,

I don't remember if the signal ISO1 is always Hi-z or low, all I remember is that it never changes its state. It must be disabled in the current firmware.
If you want to enable an external device, my best recommendation is to monitor the voltage on the wire connected to the handle holder. See the circuit on my schematic around the connector "Sleep Detect".
You just need to add one N-Mosfet, one optocoupler and two resistors (one for the gate and another for the optocoupler LED).
Your idea is interesting and useful to me. So I will implement this on my unit.
Best regards,
johnmx
 

Offline leo938

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Re: JBC Soldering Station CD-2BC - Complete Schematic & Analysis
« Reply #18 on: June 09, 2020, 08:45:26 pm »
Thanks for the reply John,

I understand your suggestion about the MOSFET but I'm think of going with something like an LPC812 instead (to switch the optocoupler) which I have lying around. Its overkill I know but I think I'll implement a 30 sec delay after the iron is replaced in the stand before shutting off the fan, simple to do in a uC.

Thanks again!
 

Offline johnmx

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Re: JBC Soldering Station CD-2BC - Complete Schematic & Analysis
« Reply #19 on: June 09, 2020, 09:29:14 pm »
Thanks for the reply John,

I understand your suggestion about the MOSFET but I'm think of going with something like an LPC812 instead (to switch the optocoupler) which I have lying around. Its overkill I know but I think I'll implement a 30 sec delay after the iron is replaced in the stand before shutting off the fan, simple to do in a uC.

Thanks again!
The signal "SLP+" may not be constant. Probably the micro is alternating between Hi-Z and +3.3V. Check this by connecting a scope between Earth (banana connector on the back) and the metal part of the handle holder. Ideally you will have to connect your circuit only to this two signals. That way you don't have to open the unit.
Best regards,
johnmx
 

Offline leo938

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Re: JBC Soldering Station CD-2BC - Complete Schematic & Analysis
« Reply #20 on: June 11, 2020, 06:38:14 pm »
John,

Just had a look at the SLP1 signal. As mentioned its grounded when the iron is in the stand & when the iron is out it has a constant 100Hz square wave (provided by SLP+ no doubt) but also frequent approx +/- 30v signals. I can only imagine they're due to the heating or temperature measurement cycles, I attach a picture of the trace.

This is no doubt why there are zener diodes on the input back to the dsPIC, to limit the voltage. I might have a look at that signal & see if it's useable.

Regards,

Leo
 
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Offline johnmx

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Re: JBC Soldering Station CD-2BC - Complete Schematic & Analysis
« Reply #21 on: June 11, 2020, 07:27:09 pm »
John,

Just had a look at the SLP1 signal. As mentioned its grounded when the iron is in the stand & when the iron is out it has a constant 100Hz square wave (provided by SLP+ no doubt) but also frequent approx +/- 30v signals. I can only imagine they're due to the heating or temperature measurement cycles, I attach a picture of the trace.

This is no doubt why there are zener diodes on the input back to the dsPIC, to limit the voltage. I might have a look at that signal & see if it's useable.

Regards,

Leo
Earth is connected to the outer part of the tip (TC) via a couple of small resistors (0.44 Ω + fuse) and to 'COM' via the thermocouple (which is almost a short circuit). 'COM' is connected to one of the outputs of the transformer (AC) when the power transistors are closed. The circuit ground is connected to the other output of the transformer. That's why you see those half cycles during tip heating.
It should not be so difficult to "filter" that signal and avoid opening the unit.
Maybe next week I will try to implement this on my unit.
Best regards,
johnmx
 

Offline leo938

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Re: JBC Soldering Station CD-2BC - Complete Schematic & Analysis
« Reply #22 on: June 17, 2020, 11:56:36 am »
Well, in the process of investigating the setup looks like I might have done some damage!  |O

Edit: Looks like I spoke too soon, seems like the magic smoke was not fully released!

For anyone interested in automatic control of a extraction fan I'll continue here:

https://www.eevblog.com/forum/reviews/jbc-soldering-station-automatic-fan-hack/
« Last Edit: June 17, 2020, 09:03:54 pm by leo938 »
 

Offline TheSchilk

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Re: JBC Soldering Station CD-2BC - Complete Schematic & Analysis
« Reply #23 on: June 22, 2020, 06:39:59 pm »

 Analog switches controls what signals feed the differential amplifier. When SW1 and SW2 are ‘0’, T_TIP represents the temperature by measuring the small voltage between TC and COM. The circuit is at this state most of the time. One time during power up and one more when the handle is connected, the circuit changes SW2 to ‘1’ during 30 ms. At this point, both inputs are connected to TC. Maybe this is used to see the offset of the amplifiers.


Could this be to enable the station to allow to use cartridges with a series TC instead of the 3 tap standard?

SparkyBG of unisolder states that the C245 carts can have both architectures, the standard where the heater current only passes through the heater, and a second version where the tip only has two connections and all current passes through the TC.

(see unisolder rpoject here: http://dangerousprototypes.com/forum/index.php?topic=7218.0#p61175
He lists the C245 as : JBC C245 (series or separate TC))

Does anybody know if there are 245 carts with the TC in series? If so what is the exact pinout? It seems logical to want to measure from the heater to the connection at mains-earth as a tip with only 2 connections would have only those two. '

The short pulses you are seeing could be the station checking for what kind of cart. is attached?

Not able to find much more info about c245 carts with series TC thought.

Another though: Could this enable short-circuit detection in case the heater fails short? Seems unnecessary because of current sensing?

 

Offline TheSchilk

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Re: JBC Soldering Station CD-2BC - Complete Schematic & Analysis
« Reply #24 on: June 22, 2020, 06:43:34 pm »
It would make sense on a station that supports the c210 handle because that handle (again, according to SparkyBG) always uses a series TC.

Am i right that the station you reverse engineered only supports the c245 handle?

 :-// all just speculation thought.
 


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