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Hello - I have some advanced troubleshooting questions in regards to touch screen operations - The touch screen operation hasn't worked since day one on one of my NanoVNA's, likely a clone (no shields installed) was a big hassle in getting a replacement ... and when the vendor said " you can still use it without a touch screen.." well. that did it for me.. I long ago got a refund so its just a troubleshooting challenge on my bench type of thing...spare parts if nothing else...
Here's the problem:
When I touch the screen, I can bring up the main start menu on the right side, but that is as far as I get. When I use touchtest, I just get a vertical straight line off on the right side and touchcal outcome never brings up the four sets of numbers.

I have loaded it with a few different versions of firmware - no change
I have replaced the screen with a new one - no change.
I have re-flowed solder around the +/- X and Y I/O pins of the micro - no change

There must be some clocks signals and other items needed for touch screen interpolation I should be checking? I'm wondering if a PC trace is missing, damaged, or a via pad not right somewhere, as I'm not finding anymore questionable solder issues under the microscope... just wondering if anyone here has been down similar roads...

Other than the touch screen issue, the unit works OK for everything else.. just be nice to get the touch screen working, otherwise it'll be a test bed device on my bench...

Thanks! Brian - KI8KY

1: Try made calibration first
Use leveler select Config->Touch cal
Touch top+left screen side
Touch bottom+right screen side

After check work, use Config->Touch Test

If all good - Save config (Confog->Save)

In not work (hardware problem):
Touch screen use +/- X and Y I/O pins for measure position - check it
For get position used ADC
For work ADC need correct voltage on on CPU VDDA (pin 9, need ~3.3V) and ground on VSSA (pin 8)

I had an interesting experience with a touchscreen. It was actually a working nano v2 for which I bought a 3.2” screen with the same interface via Ebay.

On plugging it in, all worked except the touch, so I lumbered to the calibrate routine with painful negotiation of the jog and press. Several calibration attempts failed, until I tried touching the bottom right corner when it told me to press the top left, and likewise for the other corner ( then save in Config -at least on the v2).

All well, and it works fine with the slightly bigger screen which is easier to read and actually has a virtually identical footprint of the original except a bit of the board which has the pcb tabs for the sd card ( will saw it off), and the holes do not line up for the through standoffs but a tab of glue will do instead.

I cannot post before and after pics as I cannot attach on this forum with an Ipad.

Steve L. G7PSZ

Ok, I just read the Whole msg: you've reflowed around the ribbon cable.

Did you do a continuity check from the digitizer input pins on the uP to the solder pads?

It's not a software issue. Either the input pins to the uP are bad or you have an open trace (via?) To the display connector.

If your ohmmeter has less than 3v at the leads, try measuring the resistance during touch, at the input pins to the uP with the VNA OFF.

If I remember correctly, there is a forum post with firmware to test the touchscreen.

Dear Larry,

No I did not reflow the flexible connector. The v2 uses plug-in screens, - one reason I chose it. If you had read properly, I was describing an anomoly which no one else seems to have had, where the screen calibration ( possibly of any similar device) gave “upside down instructions” until the calibration had been achieved by navigating just with the toggle switches. It could possibly arise even if the connector was a type needing reflow.

I am sorry that the information was of no interest to you. I am sure your reflow station is calling.

Steve L. G7PSZ

Hmmm...
I wasn't replying to you, Steve.
I was replying to Brian,KI8KY who has a V1 Nanovna and who started this message thread.

Also...your snide remarks are not welcome in this forum

Brian,

There is no touch screen controller chip.? The unit uses two analog inputs and two digital pins for

the X+Y+X-Y- inputs and outputs.? You can search around the internet for examples how this works.

My first thought is that the case may be interfering with the touch screen like the early H4 models had.

I assume, though, that you have operated the unit out of the case.

With different firmware, I assume you have cleared the memory?

73

Glen K4KV

So I have SAA-2n that was working have maybe turned it on a few times at most... Went to test my new ant and cable today and the screen would touch to have menu come on but that was it... the test was lines up and down and very frustrating.

I took it apart just to see what I could see.. and well it wasn't working so can't get any worse. split it in half disconnected the ribbon on the screen and didn't see anything obvious wrong. apart didn't seen to work. Well I just threw it all together and it worked for 5 min..

hopefully it work work awhile and maybe I can learn to use it vs learn to hate this device.

Anyone know how hard it is to get parts? and or where to get some? thx


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W7GEL