Reverse Engineering the Gema Powder Coating Gun Main PCB (Part 1)
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- čas přidán 2. 08. 2024
- I reverse engineer the main board of a powder coating equipment which was said to be for Gema powder coating gun. I draw the schematic and analyze what each components do. In this video, we will learn how the commercial powder coating gun works. This is a long video and you can jump to specific chapter below at any time.
0:00 Introduction
4:02 Reverse Engineering the PCB
5:52 18 Volts Unregulated Power Supply
6:33 5 Volts Regulated Power Supply
8:42 Relay Driver Circuit
12:15 Adjustable Regulated Power Supply
17:18 Oscillator Circuit
19:34 Current Limiter Circuit
23:36 Block Diagram Summary - Jak na to + styl
Great work, you gained a subscriber.
Would you be able to make the circuits available in PDF for download?
Hi. I was thinking about setting up a website where subscribers can download circuit diagrams and other stuff. In the meantime, what you can do is freeze the screen and copy the circuit diagrams. They are not that hard to redraw.
You are so incredible!!!
It is very intelligent circuit
Thanks i had meny years and i am serch
Welcome
Waths about this two IC
Hi. The first one a generic op amp. The second is an "op amp" comparator.
And i found pure sine wave between premary of cascade i have problème only in process of triggering the relay
hope you find a solution. maybe the relay driver works the same way as the circuit in this video.
I thought it was based on a filter and not a voltage multiplier
Well done you, very interesting. Are you going to use it now in place of your design?
Yes. I already made an enclosure for it. My earlier design, I will be using as is. In the future video I will probably make a comparison of a unit with and without the uA limit function.
I do reverse engineering for estun omega pcb its have same oscillantor
this is gold! the middle ic could be just a 7805, outputs a constant 5v dc. are you planning to add the uA limit function??
Hi. There could be a good reason why the designer used LM317. Posible reason is flexibility, if during production they need to use a different IC with different voltage requirement, so they will just have to change resistor values.
I already made an enclosure for this board and will use it as is. If I will have time later maybe I will build a new circuit using this design with uA limit. I saw in Alliexpress the same board for sale but with the HV cascade only having 2 wires / no uA sense connection. I asked the seller and he replied to just leave the terminal 5 (uA feedback) open. It does work. You just have to manualy adjust the voltage depending on the situation.
Gr8… really something i had been thinking about for some time now.. and heres tha answer… ( ie design of comecial psu’s). One note though… i think you should revisit the reverseengineering of the current sens block diagram… the circuit does not make sens…. Nothing really driving the display, ie no signal from the sensing part of the circuit… the only common part is a fixed ref voltage as of your schema. And the uA sens input is also strange.. what is the leftmost component in the schema.. FD2… I guess that this is the main path for the current in the primary side of the hv transformer to ground, but c12 does not make sens in that scenario… (at least, not in my mind.. ;) ) i got the feeling that there should be a diode somewhere in this part of the circuit…. Maybee…… and i guess that there might be additional traces under the op-amps that could explain possibly miising connctions in the schematic maybee…. Edit … fd2 should have said secodary side ….
Hi very good observations. There is a separate board for the 7-segment LED display driver. If you look at 3:41, the photo in eBay shows the separate display driver board that I don't have. When I turn the uA potentiometer, the output voltage of IC2 swing from 0.35v to 3.07v. On the display driver board, this value goes to some kind of analog to digital converter so that the display shows maximum value of "100 uA". The same is true with diplaying the kV with maximum value of "100 kV".
The potentiometer that is part of the voltage divider adjust the reference voltage for the comparator IC1. The non-inverting input of IC1 get the signal from Terminal 5 which is connected to the secondary of the step-up transformer. I only knew about this thanks to the very clear photos in eBay, otherwise I have no idea where to connect the current sense. FD2 is a GDT or gas discharge tube (you can google it). Inside is a spark gap and filled with inert gas so that the spark gap does not burn out. It is commonly used in 2 modes. It can be used as protection so that if certain kV is reached, a spark jumps in the gap and effectively shorting out to ground. Usually found this component in telecom outdoor cabling. It can also be used as an active component to "dampen." the high voltage. Something that is comparable to a "resistor" for high voltage. I do not have a HV probe for the oscilloscope, so I was not able to investigate further what the waveform at Terminal 05 with and without the FD2. But nevertheless, the voltage level that reach the non-inverting input of IC1 is more or less 1 volt that is within the range of the reference voltage. And so that is how the negative feedback loop is formed. All of these will be shown in Part 2 where I do a bench test of all the functional blocks. I appreciate it if you look at that video when I'm done uploading and later comment if everything makes sense. Thanks.
I will absolutely follow this. From the information, I now realise that the main current path from the lower side of the secondary must be c12, with c13 as a bleed resistor and fd2 as a protection device if c12 fails…
Have you figured out the approximate frequency of the oscillator?
@@klasmalman9249 On part 2, I probe Terminal 05 with only C12, R13, and FD2 connected. I am getting a low voltage waveform, about 1 volt peak which is within the input voltage range of IC1. Honestly, I don't know exactly how that works as to why there low voltage in that node reference to ground. I probe the primary coil of the transformer and the frequency is about 25 kHz. Frequency change with the load.
Ithing ils LM324
Hi. Yes, the first one could be LM324 general purpose op amp. The second one could be LM311 comparator. I know it is a comparator instead of an ordinary op-amp because the output is an open collector. So the output is either 0 volts and open.
Hi Phil, im Paolo from Italy. I’ve seen your video about powder coating gun , really cool! I would asq an help to you, if possible. I have buyed a onoda ionics powder coating generator, but there is no the gun, i buyed a gun but miss cascade, im looking for a cascade that works with my gun and generator . If i give you pictures of generetor/ gun and electric wire diagram of generator can you try to help me? Thanks a lot
Hi I'll try my best to help. Please send me an email for more details and I'll see what I can do. philipal2015@gmail.com
@@DIYPhil thanks Phil , i have sent you an email.💪💪👍
Dear brother good project
Pcb garbar file link
Please send Garba file
Hi. I don't have the PCB Gerber file yet. I will let you know if I got the time and actually design and fab the board.
All pcbs have the same process