I've a 80 column card for the Apple II+ and I don't have video on a videomonitor. Does someone recognize this card and does know how this card works.There are twoconnectors at the top left corner, does someone know which of them is the video output and what is the purpose of the other connector? There's a UM6845 video controller and CXK5816PN (2048 word x 8 Bit High Speed CMOS Static RAM) on the card. It seems it is not a standard Videx card.
There are two cables available with the card, one with a female rca connector and one with a male rca connector.
The male RCA plug connects to the female RCA socket on the back of the Apple II, and one of the connectors on the card. The other connector on the card connects to the female RCA lead, which then goes to the monitor. The idea is that the regular Apple II video is passed through unmodified, until you type "PR#3" at which point the card replaces the Apple II video with its own 80-column generated signal, until you type "PR#0" to turn it off again.
That doesn't help figure out which connector on the card is which, but hopefully it makes the theory of operation a little clearer.
J2 looks like the standard videx 6-pin connector, of which only the first two are needed for the video out, therefore that's the video out, and the other one is the video in. It's probably fully videx compatible.
Thank you, this makes sense: I connect the connectors as you told : at J2 the video monitor, at the other connector the video output of the Apple II+. I have video in normal mode but when I type PR #6 the screen becomes black. When I type PR #0 the computer turns back to normal mode and the cursor is back. So the card needs more attention. I tested all 74xx and 40xx chips with my Retro Chip Tester and according to the tester they're ok. The tester can read the two eproms and gives a crc value. I can try to compare with files of a standard videx card but I don't know if they're the same. I cannot test the CXK5816 ram chip and the UM6845 ctr controller and don't have spares. I will make additional measurements to see if the oscillator runs and the signal round the crt controller.
I think it might be the other way around. I think J1 is the video monitor. Just to be safe, connect only J1 to the video monitor and then type PR#6. If it works and you see the 80-column text, then you can connect J2 to the back of the Apple II.
I agree with CVT on this one. This looks like a pretty common later type of Videx compatible card which has the "soft switch" functionality built in.