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) which supports the STM DfuSe extension (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?