VDP output monochrome and strobing

[Dave]

Buy Cheap - Buy Twice

(Though it doesn't usually stop me either )

[gunrock]

Yep. This PSU has been a labour of love (and considerable cost )

[gunrock]

Hi all. After three birthdays and some family days out (it's Easter hols here), I have managed to swap out the DC-DC step up converter and it's fixed the issue.

I also have a new problem! The MTX won't boot with the keyboard attached. Disconnect it and we are good, with a Ready prompt and flashing cursor.

The cable has no signs of obvious damage and my first port of call is to replace the cable (with an IDE, recommended by Dave) but wanted to ask, can a faulty cable prevent boot? Or is something more sinister, afoot?

[Martin A]

If there is a short between pins 19 and 20 of the keyboard connector then the Z80 would be permanently held in reset. That would certainly kill any chance of thr MTX booting.

[gunrock]

Thanks Martin, that seems to be it.

The only IDE cable I could put my hands on is an old original Xbox cable, which is about a foot long , so I'll need a shorter one, but it works.

[Dave]

Look on the bright side - it's only long on one end

[gunrock]

Thanks Dave, I'll try to remember that!

I've ordered a Pi GPIO ribbon cable - seems to have the same number of pins at the same dot pitch as an IDE cable, just three times the price. Now, that's real progress...

[1024MAK]

If you have a suitable vice, you can buy IDC connectors cheaply and you can buy the IDC type ribbon cable also at reasonable prices. Or if you are very lucky, you may find a CD-ROM cable for sale...

Mark