PCW8512 CRT needs service

[Edstrom]

My second post about my bargain PCW8512, if it is the wrong place please move it!


The other day when I was booting up my pcw from a HxC emulator I suddenly saw  that my screen was missing some lines at the bottom compared to the start screen when I was running the same disk image in the MAME emulator. I started to google up some other CP/M boot screens  and indeed there should be a line at the bottom telling what Drive is active:


https://scontent-arn2-1.xx.fbcdn.net/v/t1.0-9/53147949_1858511917609419_1013668528747708416_n.jpg?_nc_cat=107&_nc_ht=scontent-arn2-1.xx&oh=4b37a96148f311ddba8d518a4c5d2fce&oe=5D323957


Mine looks like this:


https://4.bp.blogspot.com/-ix-s-QWKAHo/WsnJxSez5NI/AAAAAAAAEfI/2Ke7CzcpLIcJevxcwnsPkEtJwYMWGkQrACK4BGAYYCw/s1600/IMG_2853.jpeg


Disregard the CP/M version I have verified CP/M 1.4 to have the same last line in MAME. As the only pots on the back of the pcw are VHOLD and HHOLD I opened it up and tried to locate the VSIZE trimpot, it sits dangerously close to the high voltage so I manufactured a wooden trim screw driver and turned it. It did only resize the visible lines and I did not retrieve any of the missing ones. :-(




So has anyone any experience with these missing scanlines on a PCW? I intend to go through the service manual but maybe this is a known problem?

[Edstrom]

Hehh, I can call off this request now, I found the problem, it's software!

Apparantly CP/M reports the boot drive only when there is a single floppy drive installed, I had a second drive emulated by the HxC and the line disappeared!


I realized it when I played with the second drive in MAME, then the line vanished and I could see that it came back once I deconfigured the second drive.


No need for CRT service, yay! :-)