JBC Soldering Station CD-2BC - Complete Schematic & Analysis - Page 1
Forum section: electronics / testgear

author: johnmx
author_rank: Frequent Contributor
timestamp: June 28, 2019, 02:57:53 pm
content: 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.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~V23voltage 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. WhenSW1andSW2are ‘0’,T_TIPrepresents the temperature by measuring the small voltage betweenTCandCOM. 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 changesSW2to ‘1’ during 30 ms. At this point, both inputs are connected toTC. Maybe this is used to see the offset of the amplifiers. Sometimes, especially when the tip temperature decreases,SW1goes to ‘1’ for 300 us up to 8 ms. Now the amplifiers are measuring betweenLOADandCOM, 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_TIPis saturated and remains like that for the complete cycle.When the driver is OFF,T_TIPrepresents 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 signalT_TIP.Moving on, the optocoupler controlled by the signalISO1does nothing on this unit.Next, there is a circuit to detect when the output voltage is applied. I called the signalDETand it is active low. It goes to the active state every time the output driver is ON. I removed the 470 kΩ resistor forcing theDETto 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.TCis 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.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: June 29, 2019, 11:11:22 am
content: 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?

author: Hydron
author_rank: Super Contributor
timestamp: June 29, 2019, 12:55:14 pm
content: 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.

author: 2N3055
author_rank: Super Contributor
timestamp: June 29, 2019, 02:21:55 pm
content: Quote from: Cliff Matthews on June 29, 2019, 01:21:03 pmI 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..

author: Ribster
author_rank: Frequent Contributor
timestamp: June 29, 2019, 04:27:43 pm
content: Quote from: Hydron on June 29, 2019, 12:55:14 pmI 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.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: June 29, 2019, 04:39:20 pm
content: 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.

author: Ribster
author_rank: Frequent Contributor
timestamp: June 29, 2019, 05:04:17 pm
content: 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 posterhttp://dangerousprototypes.com/forum/viewtopic.php?f=56&t=7218&start=1140#p66362

author: simxdx
author_rank: Newbie
timestamp: July 29, 2019, 02:38:31 pm
content: Good job！

author: MSS
author_rank: Newbie
timestamp: November 01, 2019, 12:59:26 pm
content: Quote from: johnmx on June 28, 2019, 02:57:53 pmThank 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=)

author: Icchan
author_rank: Regular Contributor
timestamp: January 22, 2020, 03:16:01 am
content: 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?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

author: shangaoren
author_rank: Regular Contributor
timestamp: March 09, 2020, 10:12:50 am
content: 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 ?

author: johnmx
author_rank: Frequent Contributor
timestamp: March 09, 2020, 10:53:37 am
content: Quote from: shangaoren on March 09, 2020, 10:12:50 amAre you using a T245?Other types may have different connections.A picture is worth a thousand words (see attached).

author: shangaoren
author_rank: Regular Contributor
timestamp: March 09, 2020, 11:13:01 am
content: Yes, the broken one is a C245-789 and the other one is a c245-911

author: johnmx
author_rank: Frequent Contributor
timestamp: March 09, 2020, 11:56:37 am
content: Quote from: shangaoren on March 09, 2020, 11:13:01 amAs you can see from the attached picture on my last post, C3 is the common, C2 the heater and C1 the thermocouple.

author: shangaoren
author_rank: Regular Contributor
timestamp: March 09, 2020, 01:01:04 pm
content: sorry, your picture does not help me a lot to understand why i get this measures ^^'

author: leo938
author_rank: Contributor
timestamp: June 08, 2020, 09:46:54 pm
content: 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 mentionQuoteI 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!

author: johnmx
author_rank: Frequent Contributor
timestamp: June 08, 2020, 10:55:26 pm
content: Quote from: leo938 on June 08, 2020, 09:46:54 pmHi Leo,I don't remember if the signalISO1is 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.

author: leo938
author_rank: Contributor
timestamp: June 09, 2020, 08:45:26 pm
content: 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!

author: johnmx
author_rank: Frequent Contributor
timestamp: June 09, 2020, 09:29:14 pm
content: Quote from: leo938 on June 09, 2020, 08:45:26 pmThe 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.

author: leo938
author_rank: Contributor
timestamp: June 11, 2020, 06:38:14 pm
content: 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

author: johnmx
author_rank: Frequent Contributor
timestamp: June 11, 2020, 07:27:09 pm
content: Quote from: leo938 on June 11, 2020, 06:38:14 pmEarth 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.

author: leo938
author_rank: Contributor
timestamp: June 17, 2020, 11:56:36 am
content: Well, in the process of investigating the setup looks like I might have done some damage!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/

author: TheSchilk
author_rank: Contributor
timestamp: June 22, 2020, 06:39:59 pm
content: Quote from: johnmx on June 28, 2019, 02:57:53 pmCould 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#p61175He 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?

author: TheSchilk
author_rank: Contributor
timestamp: June 22, 2020, 06:43:34 pm
content: 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.

author: TheSchilk
author_rank: Contributor
timestamp: June 22, 2020, 06:47:53 pm
content: Looking at the schematic again, if there are 245 tips with a series TC, they must have the TC and COM pin shorted internally, otherwise how would the Heater current return through the TC pin?

author: Hydron
author_rank: Super Contributor
timestamp: June 22, 2020, 09:46:19 pm
content: I think the diagram of the cartridge in the OP's schematic is slightly wrong (or possibly can be right but isn't always!), as I have measured a few C245s and they seemed to have a series TC, as shown in the diagram in this other thread:https://www.eevblog.com/forum/projects/yet-another-controller-for-jbc-t210t245/msg3077826/#msg3077826Similar to the OP's station, my JBC BT-2BWA also only uses the "TC" connection (C1 on the other diagram) for sensing, no substation current flows through it. I just posted a bit more explanation of the operation of this station in that thread.

author: johnmx
author_rank: Frequent Contributor
timestamp: June 22, 2020, 11:09:59 pm
content: Quote from: TheSchilk on June 22, 2020, 06:47:53 pmI have more than ten C245 tips, but I only measured a couple of them. I believe they are all exactly like the schematic I posted in the first post.Do you have any complete model number of such C245 tip with the TC in series?Quote from: TheSchilk on June 22, 2020, 06:43:34 pmThe station model CD-2BC only supports the T245 Handpiece and the C245 cartridges.I give up on making the controller for the T245 handpiece. Instead I bought a new BT-2BWA for 190€. With the time required to implement such controller I can easily earn many times more than that.

author: Hydron
author_rank: Super Contributor
timestamp: June 23, 2020, 10:29:08 am
content: I measured half a dozen C245 tips and none had a thermocouple voltage present between TC and LOAD (it _was_ present between TC and COM). Note that the thermocouple voltage isn't very large - heating the tip up by hand only gives a few microvolts change.This suggests that the attachment point of the heater resistance in the diagram is incorrect, at least in some cases. The thermocouple junction is definitely between TC and COM in all cases (in both C210 and C245).It doesn't really matter however; when measuring the temperature TC and COM are used, which works regardless of where the attachment is and whether the heater current passes through the thermocouple junction or not.As for T210/C210 compatibility, both the BT-2BWA and the CD-2BC support the T210/C210 in addition to the T245/C245 (it's stated in the manual).

author: johnmx
author_rank: Frequent Contributor
timestamp: June 23, 2020, 12:00:02 pm
content: Quote from: Hydron on June 23, 2020, 10:29:08 amWhich diagram are you referring?Quote from: Hydron on June 23, 2020, 10:29:08 amYes, you're right. My previous statement was based only on the product page.

author: Jane
author_rank: Frequent Contributor
timestamp: June 23, 2020, 12:57:45 pm
content: Anyone knows how much JBC CD-2SQE is different ? How much info from this thread can be used with JBC CD-2SQE?

author: RichardSim
author_rank: Newbie
timestamp: November 14, 2020, 09:08:28 am
content: Very interesting - thank you for doing this!I believe this thread (and all other threads I've found online for that matter) has missed one important part of the schematic with regards to T210/C210 compatibility.Quote from: johnmx on June 28, 2019, 02:57:53 pmThe one remaining combination is LOAD + TC when SW1 and SW2 are both 1. I believe this will be used for T210 handles as the cartridges are wired differently (LOAD and COM are swapped), so you likely didn't run into it with your testing with a T245 handle. This is fascinating, as in other threads (and earlier in this thread) the general wisdom is that for C210 cartridges the heater and TC have no common tap between them, so every open source JBC T210/C210 controller I've found is powering the heater through the TC (and likewise measuring the TC through the heater)!Here's a diagram I found in the Unisolder thread over at the Dangerous Prototypes forum. Of note is that the T210/C210 connections do not match anything else that I've found online, however they fit the circuit here as I've described, and more importantly all my C210 cartridges appear to corroberate it. Having said that, I haven't actually hooked the cartridges up to a TC amplifier yet to be able to measure it.

author: dungo
author_rank: Newbie
timestamp: February 08, 2021, 05:06:22 am
content: Hi. I appreciate the work you did in making this diagram. It helped me a lot to repair a JBC that I got badly damaged by a short circuit. managed to repair it almost completely. I only miss the part of the PTC in which you have doubts if it is 33k. actually when looking at your diagram I saw that a 2.2k thermistor is needed to form the voltage divider and thus be able to lower the voltage to approximately 2.5v. as this jbc they removed the thermistor from the transformer and I did not find the 2.2k thermistor just put a resistor of that value. I know it is not ideal but I do not have the correct part. apparently everything works perfectly. Thanks again for your contribution.

author: Laidukas
author_rank: Newbie
timestamp: May 28, 2021, 09:52:40 pm
content: Hello everyone, I would like to buy NT115 nano handle and connect it according T210 pinout, but concern is that T210 is 40W and NT115 is 14W. Does base-unit/controller actively control delivered power to the tip? and consequently will fry the heating element of NT115? Or is it the "Keep It Simple" design where power draw is determined by heating element resistance and I can connect lower wattage tip with no worries?

author: thm_w
author_rank: Super Contributor
timestamp: May 28, 2021, 10:06:30 pm
content: Quote from: Laidukas on May 28, 2021, 09:52:40 pmYou can find some explanation here:https://github.com/Winkelkatze/jbc_nano_solder

author: cpposteve
author_rank: Regular Contributor
timestamp: December 01, 2021, 01:10:08 pm
content: HiThanks for your help.this should help me or at least try to fix my DI-2D. im having an error with mine where it shows error 2 open circuit. have been looking for a schematic for a while now to try and get to the bottom of my issue and to resurrect it. Would you happen to know what part of the circuitry would be monitoring for an open circuit? im thinking maybe the TC input but yet to probe around.here is a link to my thread as to whats been happening.https://www.eevblog.com/forum/repair/please-help-me-diagnose-my-jbc-di-2d-fault/many thanksSteve

author: Ribster
author_rank: Frequent Contributor
timestamp: December 01, 2021, 01:51:30 pm
content: I’ve had this same issue with the knock off of tips.Changing the tip resolved the issue

author: cpposteve
author_rank: Regular Contributor
timestamp: December 02, 2021, 11:02:05 pm
content: unfortunatly not in this case. all my tips are genuine and tested on this machine

author: Andrew_sokolov
author_rank: Newbie
timestamp: January 26, 2022, 03:01:25 pm
content: look at the voltage graph on the heater. I think a PID controller is used with a window of 5 pulses 50 Hz

author: c0d3z3r0
author_rank: Regular Contributor
timestamp: November 03, 2023, 09:41:13 am
content: @johnmx Did you try to dump the firmware?

author: nardisk
author_rank: Contributor
timestamp: February 07, 2025, 09:55:34 pm
content: Hi guys, you did a good job and thanks to your information I'm trying to repair my jbc for a capacitor charged with 36v it made a mess, opening the station I immediately found some damaged transistors and I also replaced op07c and with these my t210 works, the problem instead is with t245 which shows me 350 degrees but the tip does not heat enough to solder, I have not checked what the temperature really is but looking at the diagram I'm having trouble understanding the problem, my idea is to replace 74hc4053 because it seems that it is connected directly to the tc, do you have any ideas