Products > Test Equipment
JBC Soldering Station CD-2BC - Complete Schematic & Analysis
leo938:
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
johnmx:
--- Quote from: leo938 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
--- End quote ---
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.
leo938:
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/
TheSchilk:
--- Quote from: johnmx on June 28, 2019, 02:57:53 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.
--- End quote ---
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?
TheSchilk:
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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