Help needed. Acquired a C128 and Philips CM8833 II. Works fine in 40 column mode but when connected via rgbi cable no ready prompt. I plugged an Amiga into the DB9 And it works fine. Noticed that when i power it on for 80 columns there is like a colourful test screen for a couple of seconds but after that nothing. It has jiffy dos installed would this cause an issue? Or is it a faulty VDC chip?
You sure the 40/80 key is down? Run some tests in 40col mode that test the VDC and check the values. Are you sure the monitor had the digital/analogue switch in the right position? Try just changing the colour of the screen/border on 80 col (you can do all this on the 40 col screen) Do you have a 128 test cart?
Hello Pyrofer - thanks for your help. Striped down and checked all unsoldered chips were seated. Re-assembled and it worked! Used it for a couple of days and found that 80% of the time the READY prompt came up the rest I had to hold the 40/80 key down for it to work.