Agilent DSOX Oscilloscope ColorBlind Hack

I suffer the most common type of colorblindness, the red-green type, and more specifically, deuteranopia. This essentially means that I have difficulty telling colors with red and green components from each other. If you can't see anything but a bunch of dots here (as I do) but you believe you can see correctly, you may want to investigate further:


Deuteranopia test figure. I can't see anything but random dots there.


For the same reason, we colorblinds see the following two traces in the same color, we have no way to know by looking at the screen which line corresponds to channel 1 or channel 2:


Original DSOX colors, a colorblind's nightmare.


In the past, when product development cycles where much longer, companies spent much more time developing hardware and firmware. Attention to detail was huge, something that can't be said today. Back in time, HP was a lot more careful about this things. Take the old 70004 MMS display for example. It not only allows you to change colors, it even has two colorblind palettes built-in. The manual has a full chapter on color theory and color options:


HP 70004 Users Guide, chapter on color


That is the reason why I took the effort to repair the 70004 and even convert it to LCD using the kit from SimmcomLabs


HP 70004 repair (click on picture to follow)


SimmcomLabs HP 70004 LCD kit (click on picture to follow)


Appart from not giving the user the option to select the trace color, Agilent chose (as many other companies) YELLOW and GREEN for the traces on the two-channel DSOX scopes. How unfortunate... And it is not possible to change those colors, it seems it is the ASIC that has that selection hardcoded by design. Being unable to tell one trace from the other, this oscilloscope was getting less and less use, up to the point that I decided to get another scope where I could actually see which trace was which. That scope is the Lecroy Waverunner LT344L, and I had to repair it. This is what I mean by being color blind friendly:


Colorblind heaven, the Lecroy LT344L (click on picture to follow)


The Hack

As Mike suggested in response to my message in the EEVblog forums it seemed possible to rewire the LCD interface and swap the red and blue signals. That way yellow will turn bluish (red component replaced by blue) and it could be seen as "very different now" from the green trace.


TCG085WVLCG LCD module interface signals


It looks simple on paper right? Well, the idea is actually very simple. An adaptor that swaps six signal lines and keeps the rest straight pin-to pin. The problem is the 0.5mm pitch of the connector and that I wanted to test this quickly, I did not want to design PCB and wait a few weeks to receive it. That ment using 0.1mm wires to route each signal individually from one connector to the other and using kapton tape to insulate the three "layers". An hour under the microscope and it was done. Note there are 40 pins between those two fingers:


Flat cable adapter in the hand for size reference


Adapter closeup. Three "layers" with kapton insulation can be seen


Adapter installed, add a bit of tape to hold it against the PCB


The result

The UI is mostly grey or white, so swapping the red and blue channels does not change much the appearance of the interface. Warning notes that should appear red are now blue and they Agilent logo that was blue is now red.


Yellow CH1 trace appears now in some kind of blue


What does change is the color of the boot screen, that used to be mainly blue and now it is red-dish.


Boot screen shows a red sky instead of blue now :-)


I would not be myself if I could resist changing the CH1 button backlight LED to blue, to match the new trace color. So, no I couldn't:


CH1 enable button now lights up blue too !


Roberto Barrios, EB4EQA