"White Screen" Troubleshooting Tips for DSO138

Re: "White Screen" Troubleshooting Tips for DSO138

Postby rew » Wed Sep 23, 2015 9:33 am

The problem with "LCD signal" is that it is quite complicated over many wires. In normal cases, you would be developing software in parallel with debugging the hardware. That complicates things: The hardware guy says it must be a software problem and the other way around.

In this case, you have a big advantage: you KNOW the software works. And Secondly you KNOW that the hardware design is good.

The chip on the LCD module is "smart" in that it shows a "known pattern" when it has proper power but has not yet received any data from the CPU. In this case that's the white screen. (for a HD44780 controlled 16x2 character LCD its a row of blocks on the first line and a blank second line. For the displays on the Airbus A320, it's a lissajous pattern).

So: knowing that the CPU runs its software (it blinks the leds, so it must be running!) and that it is TRYING to display stuff on the LCD, you'll have to think and measure to deduce where the problem lies.
rew
 
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Re: "White Screen" Troubleshooting Tips for DSO138

Postby WrightLamb » Mon Oct 19, 2015 3:32 pm

I also worked with DSO138 and my many projects used it. I don't know much about this but have some general idea to troubleshoot it.
According to me you must make sure MCU is working. MCU status can be confirmed by pressing RESET button. If two blinks are observed after reset button is hit then MCU is working.
After MCU is confirmed working carefully check the connections between MCU and LCD module. These connections include 8 data lines and 5 control lines . Make sure they have no opens or shorts. You can use the "Test Mode" to find out opens.
WrightLamb
 
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Re: "White Screen" Troubleshooting Tips for DSO138

Postby kadir » Tue Oct 29, 2019 8:10 pm

hi all,

this problem is related to bad soldering in flex data cable between lcd and pcb. it's normally very fragile type of connector and i hate it.

so, my osc came with white screen and green led in main pcb is blinking, then i decided to re-solder lcd screen's flex cable to pcb with some soldering flux and problem solved.
kadir
 
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