Would you mind tell us where did you buy it and how much?
thx
Just curious, how to get 250MSa/S with one AD9288 BST-40 ?
There is some overclock or 2C42 version only have 80 MSa/S ?
For sure it's not good for silicon, so can add small heatsink to it.
I have seen your pictures, next time when you open it, shot some pictures of the input circuit as well.
I've added the front-ends to the picture collection:
https://github.com/wpwrak/2c42-pix/blob/master/jpg/afe.jpg
https://github.com/wpwrak/2c42-pix/blob/master/jpg/afe-zoom.jpg
There are a few unpopulated footprints in the AWG circuit, U13 and some 3-SOT part, so that AWG probably isn't fully functional. It does produce the reference square wave for probe compensation, though.
It is really my fault....Of course I could lie, but I don't want to do that.no its not your fault! you opened it up and diagnosed it is the effect of the cause that it wont get charged. this is typical china products. its lucky if we can fix it, but why we should be blamed of its unreliability? f*ck it, if its me, i close it up i'll make a report to seller, whether i did or didnt open it up, either way i'll file a complaint anyway. anyway, maybe you can find pin compatible battery charging IC in digikey? if you insist to "not lie" or want to keep it in its "crippled" form, like the one china product i have here.
anyway, maybe you can find pin compatible battery charging IC in digikey?That's what I'm trying to do. I don't even care about it being pin-compatible, there is plenty of space for bodging there. There are some very similar ICs, I just need to find something in bigger packages.
I also don't wan to deal with returns and all that stuff.yes this is another major factor why we prefer to fix it to death on our own. sometime its better the hassle than to pay 10X of the big boy brand (but maybe its just me). good luck.
Does anyone know the amplitude range supported by the AWG?I will check when I get home, but I don't remember it being particularly adjustable. I think it changes in 0.1 V increments.
What is the main processor in this? Can't read the markings on your photo.The processor is STM32 and it is under the can (which is not present on my unit) on the last picture. EDIT: Actually no, the MCU is on the other side of the board with a shield. So this looks like a newer revision of the board.
The processor is STM32 and it is under the can (which is not present on my unit) on the last picture. EDIT: Actually no, the MCU is on the other side of the board with a shield.Sorry. I edited out my question as I noticed that wpwrak had already noted what all the parts were.
The big chip is a Lattice FPGA.
Also my unit has multimeter chip markings scratched out. No idea why if they already release devices with intact markings.
Strange that they even bothered to grind off the markings on the multimeter chip in the first place. They're not doing anything special with it and it is just a basic 4000 count chip anyway.It looks like may be my hardware is older revision, so they may have thought they will be able to keep it a secret. And then just gave up on newer units.
It looks like may be my hardware is older revision, so they may have thought they will be able to keep it a secret. And then just gave up on newer units.Yeah. There are some changes to the PCB between Microcheap's A09 PCB (2018.11) and wpwrak's A07 PCB (2018). Some parts have moved around and the silkscreen has changed in places.
self restoring fuse: 200mA/250V, 4A and 10A range no fuse.Mmm... Best keep this for low voltage stuff then.
Comparing the two boards, the AWG feature needs U12 (DAC?) which is near the FPGA and U13 which is near the output. U14 (some kind buck regulator) looks to be needed as well.
self restoring fuse: 200mA/250V, 4A and 10A range no fuse.Notice that too :palm: Hey, but at least they reinforced the tracks with solder
I'm personally more bothered by overclocking 80 MSPS ADC to 250 MSPS. That's more than 3 times.
I've noticed that. wpwrak's is a newer revision an he's model has no AWG.You've got the newer version.
I forgot to check the markings on U14 and U15 as well (there is one for each battery) I will try to take some higher resolution pictures later and see if I can identify them.Maybe +/- supplies for that opamp? I can't find U15 at all on wpwrak's photos.
Everything else looks to be populated, so it should be possible do add the AWG function to the 2Cxx models.Maybe. Not sure how it determines your model though. Either something in flash or a pin strap somewhere? The firmware mentions "This model has no AWG" a couple times.
Maybe. Not sure how it determines your model though. Either something in flash or a pin strap somewhere? The firmware mentions "This model has no AWG" a couple times.No, it must be something specifically for the batteries. On the older boards those chips are not present and the batteries are simply connected in parallel.
No, it must be something specifically for the batteries. On the older boards those chips are not present and the batteries are simply connected in parallel.Yeah. That makes more sense. There is unpopulated U15 next to the +5V PSU on the older A07 board. That disappeared on the A09 board though with U14 and U15 appearing next to the two batteries. No inductor so its not the same as the U15 on the A07.
I do not know how true this is, because the guy only claims to have hacked the device. Without any affirmations.He's managed to patch the firmware to reenable the AWG on the C models. He won't release the patch however. He knows roughly what the missing parts are but doesn't know the values or the exact DAC/opamp used.
Any body measured more then 400V in DMM mode?No. The datasheet states that the maximum voltage is 600V, but I don't use nothing that generates such high voltages and if I needed to measure something in this level, I would use a more trustworthy meter.
Drop voltage in diode mode 0.999 V max, is it a hardware limit?Maybe, I couldn't find the multimeter's chipset datasheet, but apparently the CS7721CN is pin compatible with FS9721 that can measure diodes up to 1.5V. Hantek specifies the maximum 1V diode voltage in the manual, though.
Any body measured more then 400V in DMM mode?
He knows roughly what the missing parts are but doesn't know the values or the exact DAC/opamp used.
Do you have ST-Link? Can you readout a dump of from your device. It will be interesting to compare it with lower version.
The AWG of the Hantek 6xx4BD (which has roughly similar specs) uses a 5166ISZ behind the DAC902, which is a 1.4 GHz current-feedback amp. So I'm wondering wheter it is supposed to be a current feedback amp as well in the 2Dx2 models (and maybe also a faster one than OPA960)? Just a guess...
DVM is isolated from the oscilloscope, and the insulation did withstand 1kV as well, >= 2000MOhm - beyond the limit of my insulation tester
Do you have ST-Link? Can you readout a dump of from your device. It will be interesting to compare it with lower version.Sorry for the delay, but finally I had time to open my meter to extract the firmware.
After removing the board and turing it around I noticed the same as you did - the markings on the ADC are not readable.I found the manufacturer of the DAC chip it is a Chinese brand http://www.3peakic.com.cn/En/product/productes/catid/147.html (http://www.3peakic.com.cn/En/product/productes/catid/147.html) but I still can't read the part number. There is also no 12bit DAC on the manufacturer web site, maybe it's a new IC I don't know but it is apparently pin compatible with the ISL5861, AD9762 or DAC902.
Thanks for the information, I did open that thread to report some bugs I'm finding, I wanted to see Hantek's response.
Please find more details here https://www.eediscuss.com/forum.php?mod=redirect&goto=findpost&ptid=14705&pid=17746. (https://www.eediscuss.com/forum.php?mod=redirect&goto=findpost&ptid=14705&pid=17746.)
Sorry for the delay, but finally I had time to open my meter to extract the firmwareNice. The bootloader is in there as well and you've got the big block of data at the end of flash as well. Presumably that block has calibration and other things like serial number + model. What is strange is that block has "CN19XXXXXXXXXXXX-40" in it but that doesn't match up with the serial number label on your board. I wonder if the 40 indicates 40MHz since you have a 2D42. No clue if there are checksums etc...
I wonder if just changing the 40 to 70 would alter the performance.That is a good question, I'll see if I can try it later to test it
I wonder if just changing the 40 to 70 would alter the performance.Maybe it's that simple indeed! Well, some more tests is needed to confirm that it really changes the BW or it just modify the sys info page.
...which is not enough for the EL6155 in the AWG, which clipped at the negative half wave at full swing of 2.5V...
...the quality of the AWG is - uhmm - let's say: suboptimal. Clearly visible spikes and distortion everywhere...
I did some measurements in single channel mode...
...Above 80MHz the sampling rate is too low, so aliasing effects become prevalent...
No software modification is needed!Interesting. Somebody else had to modify the firmware on their version. I looked at the firmware and does have several error strings mentioning that a specific model doesn't have the AWG feature. Is it somehow detecting it from the presence/absence of the DAC?
I did some measurements in single channel mode (with -70...)
In my 2D72, the negative rail of the EL5166 measures rather about -3.3VThe mentioned -4V for the -5V rail were just from memory, I did not note the exact value. :-//
The presence of the AWG section is simply detected by R65 8) This is the DAC enable signal from the FPGA forwarded to the MCU via R65.
The chosen value of 560 Ohms is just my educated guess, some russian guy in a YouTube video used 50 Ohms.
Maybe someone with a genuine 2Dx2 could confirm the real world value of R65? The pictures in this thread are too blurry to read the marking.
I just did some calculations around the DAC:
With an Rset of 2,2k we get a fullscale output current of around 18mA, which results in a voltage drop of about 0,9V across the 50 Ohm output load (This disregards the input impedance of the OpAmp input dividers, but as I used 51 Ohm resistors anyway, the difference should be neglectible.)
As the gain of the output driver is 3,733 (560/150 Ohm) the fullscale output voltage at the BNC (without load) is 0,9V * 3,733 = +/- 3,36V.
So the DAC range isn't fully used - or is there a mistake in my calculation?
...This relatively simple-looking circuit is, however, not giving a matched gain nor a matched input impedance for the two current source outputs...
Set voltage | Digital DAC input value | Measured voltage at EL5166 output |
0V | 2062 | 2.5mV |
2.5V | 238 | 2.49V |
-2.5V | 3886 | -2.50V |
now need to downgrade to previous firmware where AWG works.
Wait, are you saying that AWG doesn't work on the newest firmware? Or it's just not working because you flashed the wrong version or what? I was planning on flashing the newest firmware this evening but if it causes AWG to stop working I guess I'll stick with what I've got.
Hello, friends.
I need to check AC wave form from power outlets (AC 220V) at home.
Can I do it with Hantek 2D72? Is probes is suitable for it? I need to use 1:10X position?
so, is it possible to hack 2d42 to make it 2d72?
so, is it possible to hack 2d42 to make it 2d72?
Yes it is, https://www.eevblog.com/forum/testgear/hantek-2c422c722d422d72/msg2220975/#msg2220975 (https://www.eevblog.com/forum/testgear/hantek-2c422c722d422d72/msg2220975/#msg2220975) but you will need to open your device and have a ST-Link v2 to reprogram de FW. The procedure is described in a few posts back.
If you try it just make sure to backup your device before do any change.
To change the BW of your scope, you will need a ST-Link and then connect it to the device as described a few msg back in this same thread: https://www.eevblog.com/forum/testgear/hantek-2c422c722d422d72/msg2186756/#msg2186756 (https://www.eevblog.com/forum/testgear/hantek-2c422c722d422d72/msg2186756/#msg2186756)
Extract the FW, open it with a Hex editor and look for the serial number in it, it will end with "-40" just change it to "-70" save and reprogram the flash memory. Now your handheld has a maximum BW of 70MHz.
Does the 2D72 have autozero/REL mode for the multimeter?No, I don't think this device has the REL mode.
Can you please help me with some hints?In the installation folder of the PC software (C:\Program Files (x86)\Hantek2xx2) there is a file named "rescure_en.txt" check it and see if it helps in your case.
When I received my unit from banggood (a 2D42), I noticed the ohm readings were bad, always measuring 1kohm or 10kohm with no leads plugged in. DC voltage was off by maybe 0.3 volts but that kinda went away by itself after while. The buzzer also had strange readings. It would beep fine but measure ~300ohms
I bought a 2D72 at aliexpress and the scope measures are off.
When measuring a battery with 7.6v the scope shows 8.4 or so volts.
Does the oscilloscope part Hantek is better than Jinhan and the FNRSI 5012-H ?
Carefully reading the forum, I couldn't find a 100% answer, is the hardware of 2X42 and 2X72 series identical or different?As far as I can tell they are identical. The only difference is that the "C" models don't have the components for the function generator soldered on the PCB.
Hi,
Does the oscilloscope part Hantek is better than Jinhan and the FNRSI 5012-H ?
Thank
Tell me, how accurate have you found the voltmeter? Its telling my a brand new Duracell 9v is 9.25 v and a 1.5v is 1.73v - this seems WAY out to me.The multimeter is precise, but a few months ago there was a batch of devices with problems in DMM mode.
Do this tests: put the multimeter in DC V mode and short the test leads to see if the display show only 0.000V, do the same with mV. After that, check the resistance (OHM), short the leads and you should see 0 ohm or a very low value. Then, test the diode mode, with nothing connected you should see 0L. Let me known the results.Mine does all this ^^^ and it is consistent with my other multimeter. I am using this tool only as a backup scope (for car, remote quick checks, AC power lines etc.) and so far I am satisfied. It has exceeded my (not too high) expectations. It is definately usable (not like the toy crap you can get for $50).
I've dumped the firmware from a new 2D72, and stored in on our GitHub at https://github.com/circuit-specialists/Hantek-2D72. Now there is a permanent place to get the files, and the README will have a list of all the mods I've found so far. Later, I'm going to order in some ST-Link V2 to sell as products in case people need to flash or unbrick their devices.
From the cheapest seller on Ali....Of course it was, that explain the problem...
One more thing, if you do the AWG mod you will need to calibrate the amplitude of the waveform, there is no need to play with the resistors values as someone posted some time ago. Just install the FW linked below using Dfuse. Use a coax cable to connect Gen Out to CH1 of the device, go to the AWG and set Sine wave, on the second page of the configuration you will see an option "calibrate", select it and it is done. You can now update to the last firmware again.
I downloaded the instructions from jace@cs on page 6 of this threat. I only changed R65 to a lower value as my first dac was not working/responding. In case you need the passive smd's, I have some spares as I ordered to much. I can send them to you if you pay the stamp (I live in the Netherlands) The ST-link and ic's I found on ebay/ali. By the way : the dac903 is a 12 bit dac...
is NOT necessary , right?
Is there a way to hack 2C(D)x2 to 2d82auto?
Caution, my Kaspersky shows a Trojan-warning when I tried to enter the eediscuss-site.
Though it might be a false alarm, but I would not bet on it.
Have done , but the result is not good 47r r is read 51r 330r = 360r 460r = 5,10K 510r = 5.6K 2k2 = 21 k 3k3 = 3.6k 4k7 = 4.6k 5k = 5k 50k =50k 200k =280k
So i can forget the measuring of Resistance with this meter. but my own fault.
42 and 72 has hardware differences.
I was supposing that, setting a sine wave with Amp at 2.5V I would have on the scope a wave with 2.5V p-p, while on the manual I have just seen within the example that the p-p value showed on the screen is 5V, so the amplitude should only be related to a semi-wave. ???
... Found that the 150ohm resistor at pin 2 of EL5166 was in short circuit, so changed with a new one. After that the things were better, but not exactly as expected. I checked the outputs from DAC and levels were ok, so I decided to change the feedback resistor on the output opamp. From 560 to 186 ...
...so I decided to change the feedback resistor on the output opamp. From 560 to 186...
Yes, you are right but, to be a simmetrical diff amplifier as I also supposed (as also suggested on ADC902E datasheet) I should have to find a resistor from U13.3 to gnd. Not being able to find it.
Is everything related to the AWG populated as in a geniune 2D72?
Are the various 0 Ohm resistors replaced with the actual values as well?
Are the 49.9 Ohm (68X) resistors from the DAC outputs to GND present?
What DC voltage do you measure from DAC pin 17 to GND, and from pin 18 to GND?
What is the value of your Rset resistor, from DAC pin 18 to GND?
When you set the AWG to rectangle with amplitude=2.5V and offset=0V, what peak-to-peak voltages do you measure on the two DAC outputs?
Expected are about 500mVpp on one output, and about 850mVpp on the other one.
Did the calibration survive a power-cycle when the HantekHTX2019031201 firmware was installed?
Just a guess: Maybe the AWG calibration data are reset by the firmware (deliberately) if the device model is not a 2Dx2, in order to motivate people to buy a 2Dx2?
If the firmware or the firmware upgrade would reset the calibration data unconditionally, then the device could never retain the factory calibration.
[ IIRC, the calibration feature was only present in the 2019031201 firmware because a bug in a previous firmware release garbled the calibration data. So Hantek had the need to provide a solution in order that users of the buggy firmware can re-create the lost calibration data. Later, the feature disappeared again. ]
Regarding it not holding the calibration data, try to restore the device to factory default to see if it makes any difference.
In the next days I will review the DAC902E datasheet in order to check, based on current Rset, res on Iout and OpAmp gain, if the output is aligned to what it should be, then I will calculate a new value for Rset and will post my considerations.
In this moment an amplitude of 1V produces 1,25V on the output channel.
Hello all. New 2c42 owner here. I am checking my hacking options here, or if anyone noticed what I did.
I tried to test the bandwidth of my scopes and my probes with a fast pulse, and a signal generator today, and it seems mine has far more than the claimed 40MHz bandwidth, probably 70Mhz or so.
Unfortunately I find it hard to tell, as there is some overshot and ringing going on, that really seems like an interpolation problem.
Unfortunately I can't get the pure ADC data out of the scope, as the display is interpolated and there are no options to change that, and even the PC software can only extract the interpolated waveform.
I wish I could get bare sample points on screen, perhaps with a linear interpolation to see more of the measurement, and less of the guesswork, but that may be just me.
I mean perhaps I could try lowering the time/div until every extracted sample corresponds to an ADC sample, but TBH I don't trust them I can get anything out of it that is not already "manipulated". I digress.
So. Did anyone do proper bandwidth tests of the 2x42, the 2x72 and a hacked 2x42? I really can't find my 40MHz limit in device, only this, what I think is a crappy interpolation artefact.
Above the 70-100MHz range it is the sample rate that limits the system anyway.
See attached picture. Good quality 10MHz signal fed in from a 50 ohm source through an 50 ohm BNC terminated coax. Looks "perfect" on a proper high bandwidth scope.
Hello all. New 2c42 owner here. I am checking my hacking options here, or if anyone noticed what I did.
I tried to test the bandwidth of my scopes and my probes with a fast pulse, and a signal generator today, and it seems mine has far more than the claimed 40MHz bandwidth, probably 70Mhz or so.
Unfortunately I find it hard to tell, as there is some overshot and ringing going on, that really seems like an interpolation problem.
Unfortunately I can't get the pure ADC data out of the scope, as the display is interpolated and there are no options to change that, and even the PC software can only extract the interpolated waveform.
I wish I could get bare sample points on screen, perhaps with a linear interpolation to see more of the measurement, and less of the guesswork, but that may be just me.
I mean perhaps I could try lowering the time/div until every extracted sample corresponds to an ADC sample, but TBH I don't trust them I can get anything out of it that is not already "manipulated". I digress.
So. Did anyone do proper bandwidth tests of the 2x42, the 2x72 and a hacked 2x42? I really can't find my 40MHz limit in device, only this, what I think is a crappy interpolation artefact.
Above the 70-100MHz range it is the sample rate that limits the system anyway.
See attached picture. Good quality 10MHz signal fed in from a 50 ohm source through an 50 ohm BNC terminated coax. Looks "perfect" on a proper high bandwidth scope.
Even after being degraded to some amount by the frontent, the pulse is still is "too fast" for the given sampling rate and contains too much high-frequency components >= fs/2. Therefore it violates the sampling theorem. Consequently a sinc interpolation can no longer reconstruct the original signal waveform exactly. An exact reconstruction is only possible if the original signal were band-limited to < fs/2 in the first place, before being sampled.
I guess the "proper high bandwidth scope" has not just a higher bandwidth, but in particular a higher sampling rate as well? (and some scopes may also have a built-in anti-aliasing filter)
It is hard (if not impossible) to measure the step response of the frontent if the sampling rate is so low. Better sweep the frequency of a sine-wave signal and find the -3dB point (with a sine wave, you can go up to almost 125MHz without violating the sampling theorem (when the sampling rate is 250MSPS), and even beyond 125MHz you could still measure the amplitude of the down-converted sine wave).
This leaves me to believe they share fundamentally the same "innards" and that the "model number bandwidth" indicated by the 3rd character of the model nomenclature is more related to establishing marketplace price points than to each model's actual instrument performance.
$ dfu-util --device 0483:* -a 0 -s 0x08005000 -U backup.bin
dfu-util 0.9
Copyright 2005-2009 Weston Schmidt, Harald Welte and OpenMoko Inc.
Copyright 2010-2016 Tormod Volden and Stefan Schmidt
This program is Free Software and has ABSOLUTELY NO WARRANTY
Please report bugs to http://sourceforge.net/p/dfu-util/tickets/
Deducing device DFU version from functional descriptor length
Opening DFU capable USB device...
ID 0483:df11
Run-time device DFU version 011a
Claiming USB DFU Interface...
Setting Alternate Setting #0 ...
Determining device status: state = dfuIDLE, status = 0
dfuIDLE, continuing
DFU mode device DFU version 011a
Device returned transfer size 1024
DfuSe interface name: "Internal Flash "
Limiting upload to end of memory segment, 503808 bytes
Upload [=========================] 100% 503808 bytes
Upload done.
$ dfu-util --device 0483:* -a 0 -D HantekHTX2020070701.dfu
dfu-util 0.9
Copyright 2005-2009 Weston Schmidt, Harald Welte and OpenMoko Inc.
Copyright 2010-2016 Tormod Volden and Stefan Schmidt
This program is Free Software and has ABSOLUTELY NO WARRANTY
Please report bugs to http://sourceforge.net/p/dfu-util/tickets/
Match product ID from file: 0000
Deducing device DFU version from functional descriptor length
Opening DFU capable USB device...
ID 0483:df11
Run-time device DFU version 011a
Claiming USB DFU Interface...
Setting Alternate Setting #0 ...
Determining device status: state = dfuIDLE, status = 0
dfuIDLE, continuing
DFU mode device DFU version 011a
Device returned transfer size 1024
DfuSe interface name: "Internal Flash "
file contains 1 DFU images
parsing DFU image 1
image for alternate setting 0, (1 elements, total size = 229444)
parsing element 1, address = 0x08005000, size = 229436
Download [=========================] 100% 229436 bytes
Download done.
done parsing DfuSe file
$ dfu-util --device 0483:* -a 0 -s 0x08005000:leave -U backup_new.bin
dfu-util 0.9
Copyright 2005-2009 Weston Schmidt, Harald Welte and OpenMoko Inc.
Copyright 2010-2016 Tormod Volden and Stefan Schmidt
This program is Free Software and has ABSOLUTELY NO WARRANTY
Please report bugs to http://sourceforge.net/p/dfu-util/tickets/
Deducing device DFU version from functional descriptor length
Opening DFU capable USB device...
ID 0483:df11
Run-time device DFU version 011a
Claiming USB DFU Interface...
Setting Alternate Setting #0 ...
Determining device status: state = dfuIDLE, status = 0
dfuIDLE, continuing
DFU mode device DFU version 011a
Device returned transfer size 1024
DfuSe interface name: "Internal Flash "
Limiting upload to end of memory segment, 503808 bytes
Upload [=========================] 100% 503808 bytes
Upload done.
Transitioning to dfuMANIFEST state
Found DFU: [0483:df11] ver=0200, devnum=9, cfg=1, intf=0, path="253-1.3", alt=2, name="@NOR Flash : M29W128F/0x64000000/0256*64Kg", serial="XXXXXXXXXXXX"
Found DFU: [0483:df11] ver=0200, devnum=9, cfg=1, intf=0, path="253-1.3", alt=1, name="@SPI Flash : M25P64/0x00000000/128*64Kg", serial="XXXXXXXXXXXX"
Found DFU: [0483:df11] ver=0200, devnum=9, cfg=1, intf=0, path="253-1.3", alt=0, name="@Internal Flash /0x08000000/06*002Ka,250*002Kg", serial="XXXXXXXXXXXX"
Just wanted to document somewhere that I was able to update firmware using dfu-util (http://dfu-util.sourceforge.net (http://dfu-util.sourceforge.net)) which supports the STM DfuSe extension (http://dfu-util.sourceforge.net/dfuse.html (http://dfu-util.sourceforge.net/dfuse.html)) used by this scope. dfu-util should be available as a package on most Linux distros, and also on macOS through homebrew, which is what I used.
Hopefully this is useful to someone!
I think I have put voltage on the terminals when the meter stand in Ohm After opening I have seen 2 o resistors on the underside of the CS7721CN chip above the banana bushes. which are burned.
If only the resistors are burned you are lucky, it's likely that you have damaged the dmm chip. Anyway, if you want to try to repair it, I opened up mine to check the resistors values: R14 is 10K 1% and R15 is 1K 1%.
I've tried to take a picture as well, it is not great but it may help.
(Attachment Link)
Just curiosity, what was the voltage you were measuring?
FWIW I got an Owon HDS272S. Night and day better.
I'm returning the Hantek though not yet sure how.
I also got a Fnirsi 1013D tablet DSO, So far it appears to be a nice solid 30 MHz DSO which simply needs good software. I bought it in hopes I can find time to make some small contribution to cracking it open.
No one knows how a tablet DSO should work. The 1013D is a good test bed.
Have Fun!
Reg
Hola por favor he averiado el tester 2c42 midiendo en tension alterna cuando lo tenia en ohmios. He cambiado las resistencias R14 y R15 que estaban quemadas pero sigue igual. He medido tensiones en la zona que indico en la foto y donde debería de haber 5 voltios hay 4,94 votios que parece estar bien pero donde hay -5 voltios he medido -3,4 voltios. Y la tercera medida es de 3,3 voltios y la medida que daba es de 2,9 voltios. También me he dado cuenta que hay un integrado LTRA que se calienta mas de lo normal al lado de estas medidas pero no encuentro datasheet.Welcome to the forum.
Pongo fotos
Hello, please, I have damaged the 2c42 tester by measuring in alternating voltage when I had it in ohms. I have changed the resistors R14 and R15 that were burned but it remains the same. I have measured voltages in the area that I indicate in the photo and where there should be 5 volts there are 4.94 volts which seems to be fine but where there is -5 volts I have measured -3.4 volts. And the third measurement is 3.3 volts and the measurement it gave is 2.9 volts. I have also noticed that there is an integrated LTRA that heats up more than normal next to these measurements but I cannot find a datasheet.
I put photos
Hello, please, I have damaged the 2c42 tester by measuring in alternating voltage when I had it in ohms. I have changed the resistors R14 and R15 that were burned but it remains the same. I have measured voltages in the area that I indicate in the photo and where there should be 5 volts there are 4.94 volts which seems to be fine but where there is -5 volts I have measured -3.4 volts. And the third measurement is 3.3 volts and the measurement it gave is 2.9 volts. I have also noticed that there is an integrated LTRA that heats up more than normal next to these measurements but I cannot find a datasheet.
I put photos
Hi.
LTRA seems to be LT1931:
https://www.analog.com/media/en/technical-documentation/data-sheets/1931fa.pdf (https://www.analog.com/media/en/technical-documentation/data-sheets/1931fa.pdf)
But for what you said, this IC seems to be working just being overloaded, something else could be damaged an taking a lot more current that the IC can provide (or its components). R14/R15 are just to close to U4, your meter is it working and just giving bad readings?, if isn't responding at all U4 probably it's gone.