At last! Excellent! I don't know why this turned into such a lengthy, frustrating and confusing (and expensive ;-) thread...
We knew that whatever you were using worked, it was all normal commercial stuff (i.e. no homemade cables etc.), your LCD worked normally without the USB cable plugged in but changed contrast when you did plug it in. Seems pretty obvious that the USB cable was the issue, either because it was defective or just happened to be a design that drew excessive current from the M100 and that the answer was to either live with the dimming or try another USB cable. Testing connector and cable continuity etc. didn't strike me as very useful and just muddying the waters... <rant off> As to your *other* (Wyse?) USB cable, I'd double-check the driver; sounds like it's either not correctly installed or it's the wrong version. Some of these devices do not install automatically in Win10. FWIW I also have two USB cables, a CH340 type that also causes this issue and a Prolific PL2303-TA based version that does not, although it probably depends more on the actual interface in the cable than the chip it uses. m ----- Original Message ----- From: Thomas Morehouse To: [email protected] Sent: Monday, April 15, 2019 8:17 PM Subject: Re: [M100] 102 com port power drain? Victory. I bought another USB/serial adapter/cable; usb to RS232. This one (sold by DTECH) works perfectly. Plugged it in, 102 screen remained normal and clear. Transferred several small text files back and forth 102 to Dell. Onward through the fog! Thanks again all. Tom M.
