Hantek DSO2xxx schematics - Page 1
Forum section: electronics / testgear

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 20, 2022, 05:05:48 pm
content: I decided to look into the Hantek DSO2xxx series because I like the hardware as a basis to play with.To get an understanding of it all reverse engineering of the schematics seems the logical first step, so that is what I started with. First up is the "User Interface Board" as it is the simplest to tackle. In the other threads about the Hantek a touch panel connector was mentioned and there is indeed room for it on the board. I soldered a connector onto it and placed a touch panel in front of the display. The rubber push cushions can be turned to lower them. They have two slots in them to slide over the metal holder.Will post some pictures of that later.An observation of the schematics shows how they handle the buttons and the encoders. They scan them in a matrix. This might explain why the response sucks when turning an encoder.For the user interface part I made three sheets. The first shows the connectors and the LCD power setup, the second shows the buttons and the encoders and the third shows the LED's.

author: gnuarm
author_rank: Super Contributor
timestamp: June 20, 2022, 06:18:34 pm
content: I don't understand what they are doing with the pots. They are pots, right? So what is the point of the diodes? Are they measuring the voltage on the wiper arm? It makes no sense to me. Can you explain?

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 20, 2022, 06:36:31 pm
content: They are not pots but rotary encoders, so just two switches that are closed and opened one after the other. That is why the diodes are there. It works as a key scanning matrix. A problem with this design is that the buttons don't have the diodes so pressing two at the same time could result in not detecting one of them. (When they are on the same scan data line)The HC4051 ic's work for both analog and digital signals. U3 is used to pull the scan lines low in following order and U2 is used to connect the scan data lines to the scanner. The HC393 is setup as a six bit counter and controls the scanning.

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 21, 2022, 08:35:04 am
content: Here are some pictures of the touch panel fitted into the housing.The rubber stoppers need to be swapped. On the picture below you can see the top one in its original orientation and the bottom one in the swapped orientation.

author: DavidAlfa
author_rank: Super Contributor
timestamp: June 21, 2022, 09:15:34 am
content: Interesting, but really, don't waste too much time with it, Hantek uses customized kernel, there're no sources, so adding new features will be almost impossible unless the functionality and its dependencies can be build as module.We've been trying to implement networking through USB (RNDIS/ECM), the usb gadget could be compiled and loaded, but the kernel was built without networking support, and this feature cannot be added as module.AFAIK, the scope already includes and loads the module tp-adc.ko, which probably includes the touch functionality, but knowing hantek, it very likely doesn't...The Goodix GT911 driver is disabled in the devicetree (Check ithere)Code:touchscreen@14 {compatible = "goodix,gt911";reg = < 0x14 >;interrupt-parent = < 0x0c >;interrupts = < 0x04 0x0a 0x02 >;pinctrl-names = "default";irq-gpios = < 0x0c 0x04 0x0a 0x00 >;reset-gpios = < 0x0c 0x04 0x09 0x00 >;status = "disabled";};

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 21, 2022, 09:35:05 am
content: I'm more interested in the hardware as a development and play platform. So write software from scratch without linux. Not as a replacement for the Hantek firmware, just for me as a hobby. I'm also interested in playing with the GOWIN FPGA.The FNIRSI-1013D code is also bare metal no linux and I like it that way, even though it means implementing a lot of things yourself.I did notice someone on the forum informing about the schematics a while back, and that is why I thought, lets post what I'm making here. The main board will take a bit of time since I also have to draw the symbols for some of the parts. The F1C100s I already did for the FNIRSI

author: DavidAlfa
author_rank: Super Contributor
timestamp: June 21, 2022, 10:39:02 am
content: Definitely baremetal could boost things up, but also make it very complicated, as every function needs to be done at low level and probably from scrap!I think you already know, made a basic connection list in the hacking thread... but the ADC/FPGA are massive and have a *ton* of pins...Adding all the current DSO functions would take years of work. For sure, Hantek uses its existing library, common-for-all, porting it for each hardware and enabling/disabling different parts.I'll gladly help in what doesn't risk my hw! I don't think I'm opening my scope anymore, had to re-solder many pins as the solder is very soft, will warp and short very easily when probing with the DMM tips...Be prepared, you'll enter the dangerous infinite loop of "Plz do this for me" and "Your FW is crap, why doesn't do what a $2000 DSO can?"

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 21, 2022, 10:48:03 am
content: Quote from: DavidAlfa on June 21, 2022, 10:39:02 amYou are right, that is something I'm not going intoIf I manage to make something useful it will be "it is this and nothing more" in a github repository.

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 24, 2022, 05:13:42 pm
content: Was a bit of a search to get the FPGA pin out above boardNot sure if there is a proper pin out document from Gowin, but all I found was UG229E "GW2AR series of FPGA Products Package & Pinout User Guide" and UG206-1.1E "GW2A/GW2AR series of FPGA Products Schematic Manual" and neither gave a proper pin out. Resorted to the schematic of a development board they make. (DK_START_GW2AR-LV18EQ144PC8I7_V1.1) and made my own symbol in EasyEda.Still a lot of work to be done, but here is a sample of the FPGA, ADC and DAC so far.The connections between these IC's were easy. Just follow the traces on the top side and count the pins.Next up is the processor and the connection to the user interface board.

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 26, 2022, 10:00:22 am
content: @DavidAlfa: Hi David, have you ever tried to hook a SD card slot to the test points on the main board?For as far as I can see and measure the SD card interface of the F1C100s is not used, and for me that seems a missed opportunity. Sure I know they are penny f..ers, but how much of a difference does it make. They could have used a xGB SD card instead of the winbond 25N01G FLASH chip. This would have meant a good amount of onboard storage for images and easier maintenance of the OS and firmware.The test-point numbers are the actual pin numbers on the F1C100s.

author: DavidAlfa
author_rank: Super Contributor
timestamp: June 26, 2022, 03:42:54 pm
content: Nope I haven't, thought about it then realized...why?I still would have to deal with the kernel, devicetree, root data, filesystem... Nobody cares, why would I waste my time, f** itI don't think you need probing:Quote from: DavidAlfa on June 04, 2021, 03:15:03 amGPIO Table:GPIO table(Page 14):Code:GPIOCPC0 SPI0_CLK SDC1_CLKPC1 SPI0_CS SDC1_CMDPC2 SPI0_MISO SDC1_D0GPIODPD18 LCD_CLK SPI0_CS EINTD18PD19 LCD_DE SPI0_MOSI EINTD19PD20 LCD_HSYNC SPI0_CLK EINTD20PD21 LCD_VSYNC SPI0_MISO EINTD21GPIOFPF0 SDC0_D1 DBG_MSPF1 SDC0_D0 DBG_DIPF2 SDC0_CLK UART0_RXPF3 SDC0_CMD DBG_DOPF4 SDC0_D3 UART0_TXPF5 SDC0_D2 DBG_CKSo, SD0 pins seem to be free (PF5-PF0, pins 53-58).There're no vias in these pads, and there's no space under the SoC to put them, so they seem to be completely unused.Looks like they routed the unused pins to test points, just like UART1... good.SD1 pins (PC0-PC2) are used by SPI0, for the SPI nand.Alternative SPI0 pins are used for the LCD (PD18-PD21)The easiest way to see the use of a pin is by reading Pn_CFG registers on the livesystem, then check the tables on theUser manual(Page 117)The registers can be accesed like normal memory from linux, so:- PIO Base addr: 0x01C20800- PF only has Configure Register 0 (Offset: 0xB4)Code:# devmem 0x01C208B4 320x00373733Decoding 0x00373733:Code:RESV DGB_CK RESV DIS RESV DGB_DO RESV DIS RESV DBG_DI RESV DBG_MS000000000 011 0 111 0 011 0 111 0 011 0 011So SD0 pins are used by the debugger. I don't think it's important, I'm sure you could set this register to interface the SD.Reg bits for SD: 010 0 010 0 010 0 010 0 010 0 010Code:# devmem 0x01C208B4 32 0x222222At least, I've tried and didn't got any issues.

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 26, 2022, 04:25:45 pm
content: Thanks David,but my probing shows thatCode:28 GPIO116 PD20 LCD_HSYNC LCD29 GPIO117 PD21 LCD_VSYNC LCDAre not connected to the LCD but to the touch panel as the reset and interrupt line. Apparently there are LCD panels that can operate without these sync signals. Have to verify it with both boards connected to be sure.Also noticed that the other UART on the F1C100s is not used and fed into test points. They could have made a better design where the user interface hardware is not handled by the FPGA but with a separate MCU like FNIRSI did in the 1014D. Response would have been better for sure.Your list does help on some pins I do not have yet, and confirm what I have so far.Doing these reversals makes me wonder what designers are thinking. I can see better way's both in the Hantek and the FNIRSI's of doing things.

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 29, 2022, 04:46:25 pm
content: It is quite the job, but I'm getting along.The digital side of the board is done, including the ADC and the DAC with it's amplifier circuit. Need to polish some sheets to finish things.Verified that the LCD is indeed working without the vertical and horizontal sync signals. Pin 8 on the LCD connector is a mode pin that selects between just using the DE signal or the sync signals. Found the datasheet for itThis picture shows what I already incorporated into the schematics. Try to be accurate

author: DavidAlfa
author_rank: Super Contributor
timestamp: June 30, 2022, 12:31:10 am
content: AFAIK, I didn't probe the LCD signals, but extracted them from the config registers.Check those pins with another dso to see if there're sync signals.Sure, they might not be used or connected...

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 30, 2022, 05:31:22 am
content: Did not do that yet, but have it on the list, because the touch panel won't like it if there is a signal on the reset line, and the MCU might not like being pulled low by the interrupt line of the touch panel when it is outputting a signalI found some weird stuff done in the scope with the power supply TR line. Know it is a 50Hz signal (might be 60Hz in countries with this mains frequency) from the Hantek threads. It is routed to a 74 Schmitt trigger buffer and then routed to the FPGA on pin 128. Nothing weird there, but the output of the buffer is also used to control pull ups on the clock and load line for the led 74HC595 shift register. (U4 in the LED schematic)Why I don't know, but it means they can only clock this shift register when the TR signal is high

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 30, 2022, 11:28:51 am
content: For those interested, here is what I made of it so far.On the FPGA I still need to fill in two pins which go to the analog part of the system.What remains is the two analog channels with it's support hardware.Edit: Fixed the capacitor polarity in the analog -5V supply.

author: arturmariojr
author_rank: Contributor
timestamp: July 01, 2022, 10:32:05 am
content: Wow! Great work! Many thanks for your big effort doing this!!!!

author: pcprogrammer
author_rank: Super Contributor
timestamp: July 04, 2022, 05:43:09 pm
content: It is a bit of a mess that needs a lot of cleanup but here is the schematic for channel 1.Was a bit of a job to find all the connections. Especially with these low value resistors beeping the connections is tricky. Have to look at the meter to see it being 0.000 instead of 0.005 or so.I'm not very good with analog stuff so no idea if it all makes sense

author: DavidAlfa
author_rank: Super Contributor
timestamp: July 06, 2022, 01:35:07 am
content: Holy s.. , that's a lot of work!Are you able to measure those pF...nF little caps?

author: pcprogrammer
author_rank: Super Contributor
timestamp: July 06, 2022, 03:14:18 am
content: Measuring the caps probably needs removing them from the board, which I don't want to do.I have a cheap component tester (LCR meter) but doing in circuit measurements won't yield good results I think.

author: morgan_flint
author_rank: Regular Contributor
timestamp: July 07, 2022, 09:37:58 am
content: Hello, pcprogrammer! Great job!!If you think it's worth it, and after you consider the work is finished, maybe it would be a good idea to create a single .pdf with all the schematics where the labels, components, etc. would be in searchable text form. I'm not familiar with the program but maybe just printing to pdf from EasyEda would do the trick.The main advantage would be that it would be possible to search for the different circuit labels so it would be fast and easy to follow the signal path between the different sheets.Thank you very much for your work!!

author: morgan_flint
author_rank: Regular Contributor
timestamp: July 07, 2022, 09:47:37 am
content: Quote from: pcprogrammer on June 30, 2022, 05:31:22 amCould this be some kind of 50-60 Hz PWM for the LEDs in the display board?Talking about battery power conversions, I remember somebody posted on one of the other threads that, in the absence of the 50-60 Hz signal from the power supply, the scope wasn't working correctly. Maybe it's related to this strange use of the signal. But I also remember that I experimented with disconnecting the TR from the power supply to the main board and didn't notice any misfunctioning...P.S:Here is the postwhere crysti reported the problem andhere is the postwhere I said I did that experiment. The previous post includes a simplified power supply schematic

author: pcprogrammer
author_rank: Super Contributor
timestamp: July 07, 2022, 09:54:54 am
content: Hi morgan_flint,you are welcome. and yes I can make a single PDF per board. I'm gathering datasheets in a github repository and will add the EasyEda files there too.https://github.com/pecostm32/Hantek_DSO2000But I have to finish the analog schematics first, which may take some time due to laying a terrace with "lauze" which are thin stones. A hell of a job that takes a lot of energy. Unfortunately the guy we found to do the job for cheap got a MRSA infection in his right hand and is no longer able to do the job, so have to do it myself.Due to an overlap in component numbering I have to keep the two boards in separate projects, but I guess that is not such a big of a deal when one needs to work on the scope.As soon as it is done I will post it here.Regards,Peter

author: pcprogrammer
author_rank: Super Contributor
timestamp: July 07, 2022, 10:01:17 am
content: Quote from: morgan_flint on July 07, 2022, 09:47:37 amI don't think it is a PWM for the LED's. It only affects the clock and load signal for the LED shift register. No idea what is done with the signal in the FPGA, but it might well be that if the signal is tied to VCC it just works. When tied to ground the LED's may or may not function. Depends on the output strength of the FPGA. Pull-ups versus pull-downs.I ordered a longer flat cable for between the main board and the user interface board to be able to do measurements on the scope. Once it gets here I plan to look into these things.

author: pcprogrammer
author_rank: Super Contributor
timestamp: July 08, 2022, 12:24:08 pm
content: Did channel 2 and hope the redrawing makes it more readable.I'm not to familiar with the user interface and have a question about two of the control signals.The first control signal switches the input relay and I named it CHANNEL2_FILTER, but I'm not sure to what menu item this belongs to. Then there is also a control signal I named CHANNEL2_X, which enables a capacitor to ground right after U28, so also looks like a filter. But again the question which menu item this belongs to.Still need to cleanup channel 1 and the control signals sheet and number the sheets before it is done.

author: tunk
author_rank: Super Contributor
timestamp: July 08, 2022, 12:46:13 pm
content: Quote from: pcprogrammer on July 08, 2022, 12:24:08 pmDon't have a clue - could it possibly be the 20MHz bandwidth limit?

author: pcprogrammer
author_rank: Super Contributor
timestamp: July 08, 2022, 02:08:38 pm
content: That was what I was thinking too, but then I noticed the other part with the cap to ground via the transistor. I guess that is an actual low pass filter.Maybe when I start measuring on the thigh I can find out

author: pcprogrammer
author_rank: Super Contributor
timestamp: July 09, 2022, 01:32:26 pm
content: Had to swap signal for the LCD on the connector between the two boards, so here are the latest schematics for the user interface board.Also added the archive for EasyEda.

author: pcprogrammer
author_rank: Super Contributor
timestamp: July 09, 2022, 01:35:03 pm
content: And here are the schematics for the main board.

author: morgan_flint
author_rank: Regular Contributor
timestamp: July 10, 2022, 08:57:41 am
content: Quote from: tunk on July 08, 2022, 12:46:13 pmI also thought of that but, in that case, you should hear the really clicking when switching the bandwidth limiting on and off from the menus and, in my case, I can't hear it

author: pcprogrammer
author_rank: Super Contributor
timestamp: July 10, 2022, 09:03:07 am
content: I received the cable and have things setup to do measurements. Will see if I can find which setting controls this.Edit: Found what is controlling that signal I named CHANNELx_FILTER. It has to do with the sensitivity. When you set the input sensitivity to 2 volts per division or below the relay is turned off. When you set it to 5 volts per division or above it turns on.Looking at the schematic, it does add a resistive divider to the signal path. But also additional parallel capacitance. Guess I should rename the signal.Edit2: The signal I named CHANNELx_X is indeed the 20MHz bandwidth limiting filter.Also looked at the touch panel RESET and INT signals and these indeed have the LCD sync pulses on them. So to allow the touch panel to work within the Linux system a change to the LCD driver code or setup would be needed.

author: DavidAlfa
author_rank: Super Contributor
timestamp: July 16, 2022, 03:27:10 pm
content: I tried disabling sync signals in PD config register 2 (PD20 & PD21 = disabled):Code:devmem 0x01C20874 32 0x00772222LCD kept working normally, so you can keep going.Just to ensure the register was working, I disabled LCD_DE:Code:devmem 0x01C20874 32 0x00227222Then LCD_CLK :Code:devmem 0x01C20874 32 0x00222722Both stopped the LCD from working correctly.Disabling any Data pin affected the colors, as expected.

author: pu6k1n
author_rank: Contributor
timestamp: July 29, 2022, 12:02:09 pm
content: Where did 1 GS/s come from if the ADC08D502 has a maximum conversion rate per 1 channel: 500 MSPS??? According to the scheme, the connection of both channels is absent. There is an input multiplexer inside the ADC, but is there a word about it in the datasheet?

author: pcprogrammer
author_rank: Super Contributor
timestamp: July 29, 2022, 01:04:11 pm
content: That is why in the schematic the ADC08D500 is used. This one has the ability to sample one channel with both ADC'sThe scope can only do 1GSa/s on a single channel. The moment you enable two channels the rate drops.A copy of the datasheet is here:https://raw.githubusercontent.com/pecostm32/Hantek_DSO2000/main/Datasheets/adc08d500.pdf

author: pu6k1n
author_rank: Contributor
timestamp: July 30, 2022, 02:15:09 pm
content: What is the P5 "FEL" button for? Why stop memory?

author: pcprogrammer
author_rank: Super Contributor
timestamp: July 30, 2022, 03:15:14 pm
content: The F1C100s MCU has a boot loader that can load code from FLASH (SPI), SD/MMC card or go into the so called FEL mode. In this FEL mode it is possible to connect the MCU to a computer via USB. On the PC there is a tool sunxi-fel, which runs under linux, with which it is possible to read or write the MCU registers and SRAM, but not the DRAM, because that needs initialization.By disabling the FLASH the MCU will go into this FEL mode when powered up.See the other threads about the Hantek for more information on this.

author: pu6k1n
author_rank: Contributor
timestamp: August 04, 2022, 09:49:51 am
content: Does anyone have a full nand w25n01g memory dump for dso2d15?

author: DavidAlfa
author_rank: Super Contributor
timestamp: August 04, 2022, 10:33:36 am
content: May I ask why do you need it?

author: pu6k1n
author_rank: Contributor
timestamp: August 05, 2022, 02:45:28 pm
content: Look at how much the dumps in nand itself differ between models.

author: DavidAlfa
author_rank: Super Contributor
timestamp: August 05, 2022, 06:16:00 pm
content: As far as I know, nothing else than cache/system.inf file.Hantek platform-tools don't care about the model, rewrites the whole flash.After that, you get unknown model, but all options become enabled.Better you continue this in the hacking thread, this is only for schematic, let's keep everything tidy

author: pu6k1n
author_rank: Contributor
timestamp: August 10, 2022, 01:39:10 pm
content: I copied the circuit completely from the DSO2C10 power supply unit, do not judge strictly

author: morgan_flint
author_rank: Regular Contributor
timestamp: October 17, 2022, 11:41:02 am
content: Hello, pcprogrammer!I think I found an error in the schematics (Mainboard/External_Interfaces): R21 should be R16 and R16 should be R196.I'm thinking of installing J4 for the serial port (or, maybe, a more practical connector), so I was inspecting this part of the board. BTW, I've been using the serial port extensively and SERIAL_READY signal seems to be unnecessary for it to work. What could be its purpose?I've also noted that if the serial to USB is connected to the scope but not to the PC the boot procedure stops when showing the QR code and freezes there (maybe that's the purpose...).Thanks for your (immense) work!

author: pcprogrammer
author_rank: Super Contributor
timestamp: October 17, 2022, 12:12:25 pm
content: Hi morgan_flint, looks like you are onto somethingLooking at the photo I used to do this work also shows that the connector is J2 instead of J4.R21 needs to be named R16 indeed. Also noticed that R32 has a ohms value assigned, but since it is not on the board it will not be correct.I will look into this further and modify the schematics.The signal SERIAL_READY is connected to the F1C100s and I just named it as such because I think it is some handshake signal, but most likely not used in the software. The fact that the scope hangs when a USB to serial interface is connected, probably has to do with the boot loader. I have seen this happen on a Lichee nano too, when I was playing around with linux on a F1C100s. Not sure why this happens. Was in the time I was starting with the reverse engineering of the FNIRSI-1013D. Did not investigate it further since the FNIRSI scope does not use linux.But good to know this, because I was thinking of integrating a CH340 USB to serial module in the scope, but if it would need to be connected to a PC to allow the scope to start is not what one wants

author: pcprogrammer
author_rank: Super Contributor
timestamp: October 17, 2022, 12:54:24 pm
content: The schematic has been updated and uploaded to the repository.https://github.com/pecostm32/Hantek_DSO2000/tree/main/Schematics

author: DavidAlfa
author_rank: Super Contributor
timestamp: October 17, 2022, 03:51:31 pm
content: I'm convinced that what you call "serial ready" signal was actually used as some sort of system reset when the system hanged during development. Probably a hardware interrupt was set on pin value change.The issue you're having is probably caused by the Rx line being pulled low by the unconnected (Thus unpowered) usb-ttl adaptor, causing random chars being received by the bootloader, entering the boot shell.Also check there's a tiny via just over R32, in the trace going to the CPU.It must be going somewhere else, your schematic seems to be lacking this.I checked that back in the day, but can't remember, perhabs it also goes to the fpga reset pin (RECONFIG)?

author: morgan_flint
author_rank: Regular Contributor
timestamp: October 17, 2022, 05:06:04 pm
content: Quote from: pcprogrammer on October 17, 2022, 12:12:25 pmJust in case my memory was teasing me, I've just checked and it effectively hangs if powered on with the serial to USB not connected to the PCI've also verified that if you connect it to the PC with the scope "hanged", the dialog that appears is the same that when you hit a key at the beginning of the boot procedure to stop it (see attached images, first one connecting USB after powering the scope and the second one keeping a key pressed during boot) so yes, it's the boot procedure that stops when USB is not connected (apparently this is equivalent to hit a key...).Finally, this also may happen because the CH341A in my adapter is powered from the USB, not from the scope. I'll make an experiment on this and report back.EDIT: Done! Tried powering up the scope with the CH314A connected to TX, RXand3.3V but not to the PC and it didn't hang. I tested it three times because in one of the tests it also booted OK without 3.3V... maybe some loose connection or something, but most times it hangs on boot when TX and RX are connected to unpowered CH341. So maybe you can integrate the module into the scope as long as it's powered from the scope. I don't know if this will bring new problems when connecting USB to the PC with the scope on (of course, the module would have to be modified, removing the 5V to 3.3V regulator, for example)EDIT 2: The CH341A module I'm using is the one known as "CH341A Mini Programmer (Black Edition)",modified for 3.3V interface

author: pcprogrammer
author_rank: Super Contributor
timestamp: October 17, 2022, 06:55:52 pm
content: Quote from: DavidAlfa on October 17, 2022, 03:51:31 pmIt might well be that I missed that. I will see if I can trace it on the photos I have of the PCB. Not going to open up the scope though if it is not doable from the photos

author: pcprogrammer
author_rank: Super Contributor
timestamp: October 17, 2022, 07:00:04 pm
content: Quote from: morgan_flint on October 17, 2022, 05:06:04 pmThis verifies what David wrote. A simple fix could also be to just ad a pull up resistor to the RX line without powering the module. But this is something for later to test.Still very busy with the reversal of the FNIRSI FPGA.

author: morgan_flint
author_rank: Regular Contributor
timestamp: October 18, 2022, 11:55:44 am
content: Quote from: pcprogrammer on October 17, 2022, 06:55:52 pmAttached there is a photo of the bottom side of the PCB in that zone. Apparently, that via is not connected in the bottom side... Has this PCB intermediate layers?

author: pcprogrammer
author_rank: Super Contributor
timestamp: October 18, 2022, 12:01:29 pm
content: Hi morgan_flint,for as far as I know it is just a double layer PCB. I just checked it on the photos I used during the reverse engineering and found the same as you. Here is a capture from what I have with also the via marked where the trace continues in the direction of the MCU.

author: DavidAlfa
author_rank: Super Contributor
timestamp: October 18, 2022, 01:59:10 pm
content: AFAIK it's 2-layer only, then it's a little layout bug made by the trainees at hantek

author: DavidAlfa
author_rank: Super Contributor
timestamp: November 01, 2022, 11:14:15 am
content: Is it me, or the AWG output protection diode D5 placement was a VERY bad idea?External peaks will go right away into the +-5V analog voltage without any limitation, potentially killing a lot of stuff.The diode and/or traces/pcb will burn in no time, and if the diode opens the voltage will reach the amplifier anyways.Such stupid design. Should be placed at the pin 6 of the amplifier, so R9, R11, R143 limit the current, yet protecting the amp.In the worst case, the damage will be just a burnt resistor.

author: pcprogrammer
author_rank: Super Contributor
timestamp: November 01, 2022, 11:39:46 am
content: Yep would have been better. Always think twice before connecting something to this input/output.

author: gnuarm
author_rank: Super Contributor
timestamp: December 28, 2022, 06:27:58 pm
content: Quote from: DavidAlfa on November 01, 2022, 11:14:15 amI'm confused. There are resistors totaling 50 ohms in either path. That's 100 mA if you apply 10V when using the AWG. If using the external trigger, it's 100 mA at 8.3V.QuoteAm I looking at a modified schematic? What you think it should be? If so, I agree.Although, I have done exactly this on designs before. If there is no option for series resistance, this is still an effective way to deal with static.Hmmm, you are making me rethink this. The design I'm referring to runs the signals through an analog switch for isolation. The diodes are to ±12V on the connector side. The 12V supply is on the motherboard and is supplying 8 of these circuits plus the motherboard circuitry. The -12V is very light. The idea of sinking the excess voltage into the supply, is that the normal supply current is greater than the surge current. The -12V rail likely has almost no current. So that's not good. I thought the switches were ESD protected internally, but I only find this for one of the part numbers used. I guess that's why I added the diodes.This is to a connector used for serial ports of different standards (RS-232, 422, 449, etc), and audio. Not likely to be driven by anything beyond ±12V other than static. Are networking equipment rooms anti-static protected?I'm redesigning this card to replace EOL components. I will need to take better notes this time. They've asked me to use parts that are expected to be in production for 10 years. Not sure how that's going to happen. They have a service that evaluates parts for them. It will be interesting to see what they come up with.

author: pcprogrammer
author_rank: Super Contributor
timestamp: December 28, 2022, 07:46:49 pm
content: Quote from: gnuarm on December 28, 2022, 06:27:58 pmYep that is a modified schematic. The original is here:https://github.com/pecostm32/Hantek_DSO2000/blob/main/Schematics/Mainboard/Waveform%20Generator.png

author: gnuarm
author_rank: Super Contributor
timestamp: December 29, 2022, 01:11:54 am
content: Quote from: pcprogrammer on December 28, 2022, 07:46:49 pmOk, but 50 ohms is not going to make much diference really. If the input is connected to +12V that's going to be 240 mA. I use the diode clamp to prevent an ESD surge from reaching the chip inputs. Fed into the power line means the capacitance of the power bus will absorb most of the surge. The devices themselves typically have ESD diodes into the power rails, so in reality, the added diodes are just protecting the on chip diodes.

author: pcprogrammer
author_rank: Super Contributor
timestamp: December 29, 2022, 07:04:50 am
content: And that is why the manual of the scope states that the allowed voltage on the trigger input is 0 - 3.3V only.Quote

author: DavidAlfa
author_rank: Super Contributor
timestamp: December 29, 2022, 09:19:33 am
content: Quote from: gnuarm on December 29, 2022, 01:11:54 amReally? The +-5V supplies have a load of about +600, -250mA.Without resistor, a wire moves, the clip snaps, briefly touching 12V, but you have very low impedance path to +5V through the diode, being such small diode it'll will blow apart, and pray nothing else gets damaged.With 50R in series, you'll have (12-5)/50=140mA max, the resistor will survive a quick "touch" instead destroying your frontend.And if you hold the connection for longer, the resistor will dissipate ~1W, will act as a fuse, limiting the damage.

author: gnuarm
author_rank: Super Contributor
timestamp: December 31, 2022, 08:17:33 pm
content: QuoteThank you for making my case.

author: enot
author_rank: Newbie
timestamp: March 02, 2023, 10:01:26 am
content: I drew a diagram of the power supply (new type, Batch202207)

author: eurotips
author_rank: Newbie
timestamp: December 09, 2023, 07:40:52 pm
content: The TR signal in power supply adapter is the synchronization with the AC network. I would like to power scope from a LiPo battery. Is it necessary ?

author: morgan_flint
author_rank: Regular Contributor
timestamp: March 22, 2024, 10:25:38 am
content: Quote from: eurotips on December 09, 2023, 07:40:52 pmProbably not, but readhere

author: testName37
author_rank: Newbie
timestamp: June 07, 2024, 10:58:38 am
content: Hello the R136/R137 and R236/R237 are not 12,2K Ohms. It's 50Ohms (PCB view:https://youtu.be/Mmx7eo9STXE?t=1972) In my DSO2D15 its also 50 Ohms. Its mistake in schematic or in my device?

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 07, 2024, 04:10:31 pm
content: Quote from: testName37 on June 07, 2024, 10:58:38 amI have no idea. I have drawn up the schematics 2 years ago by tracing the signals on the PCB and dotting down the values. Never checked if the schematics make any sense. Not going to open it up again to check either.If your scope is working it is working and I would not bother with it. The schematics are just there for simple reference for someone who wants to reverse engineer it in some way and get some idea about the setup. It is not an original schematic from the manufacturer.