Attachment | Size |
---|---|
![]() | 3.51 MB |
![]() | 2.38 MB |
![]() | 2.22 MB |
![]() | 2.2 MB |
I have an apple 2plus clone (sherry). This always produced a messed up screen in HGR but with colour, and of course the wrong colours. It's a 14,318 crystal and jumpers are set to pal/50 and I use it with a lcd monitor. After one year of trying to sort out this messed screen, I found today that the /7M trace from B1 was broken, once I restored it I now get full grapahic and in perfect colour. But how is this actually possible??? I'm using a standard Apple ROM not a special ITT ROM, there is no special PAL card in it, and the layout seems like a rev 7 copy all TTL no special chips. I thought this was impossible?
The last image is how it was for the last year before I found the back track.
Thx
It is not possible to produce PAL with a 14.31818 MHz crystal and without a PAL card. This machine is either producing NTSC or NTSC-50.
So you think the LCD is picking it up as NTSC, makes sense but if I switch the jumpers over to NTSC/60 the image shrinks vertically. Come to think of it did also install A14 about six months ago as i found it reduced the sync pulse signal by half as the LCD was having problems to lock on. And I moved one lead from pin 2 to 3 on c13 to move the colour burst more left as it was showing on the screen border before but I just thought this was all pal. Anyway I'm over the moon now.
This switch that you’re talking about, it most likely switches between 50 and 60 Hz. The machine is producing NTSC, so you are switching between regular NTSC (NTSC-60) and NTSC-50, which your monitor happens to support.
I think CVT is right. The monitor in question supports both NTSC and PAL and possibly even NTSC-50. From what I understand quite a few do but don't really advertise it. I know back in the CRT days and even up into LCD panels Phillips made a lot of monitor and TVs which supported a bunch of standards including things like SECAM.
As a side note, I lucked out in the opposite direction. A friend of mine in Hong Kong found a Chinese Educational Computer CEC-I for me from somewhere in China. These are super rate in the US. They are basically a ][+ clone with only one slot (which requires a riser card to use most Apple II cards which he also procured for me) and Disk II controller built in. They are 240V and PAL, I bought a 120V->240V converter and was fortunate that one of the composite->HDMI converters I have supports PAL even though it isn't documented to do so. I have several of these converters and only one of them can handle PAL, so it is hit or miss. Even ones that externally look pretty similar may or may not.