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Very interesting thanks! So the Europlus is 100% black and white even with an NTSC monitor. Cheers!
My understanding is that to get color you need a PAL card and I think it needs to go in slot 7.
indeed. I thought that it would display proper NTSC out of the box but no so that's good to know.
There are a bunch of mods that were done to the NTSC boards to make them generate PAL timings. It is my understanding that if these mods are done it can't generate NTSC color any more. Supposedly it is possible to reverse those mods. But frankly I wouldn't do that on a vintage machine if it were mine. If I had a EuroPlus and wanted color I'd get a PAL card and then probably see if there is a PAL to HDMI adapter, or maybe I'd get one of the Apple II VGA cards. I just built a few of those and man do they work good. Super clear and crisp color display.
It is very easy to convert an Apple II Europlus to NTSC:
1. Replace the crystal with a 14.31818 MHz crystal and connect a trimmer capacitor in series to it. The capacitance of the trimmer needs to be around 25 pF:
Crystal for NTSC.jpg
2. Separate the circular pads and connect the bow tie pads on the motherboard:
To NTSC.JPG
Result (my Apple II Europlus producing color NTSC video):
Result.JPG
Thank you CVT, appreciated!
This Europlus is going to be on display in a small no-profit local museum so we want it as it was intended but it's a nice thing to know for sure!
I understand completely and in this case I would suggest a green CRT monitor from the 80s, in case you can't get a hold of the original Apple II monochrome monitor. Don't bother looking for a PAL card, because they were absolutely terrible in terms of picture quality. Only go with a color monitor if you can get a hold of a good RGB card.
ahah good to hear about the PAL card!
Yes, we do have an Apple monitor II which I have also restored so the system is going to be up and running this weekend! :)
I personally have an RGB capture device and I know the Apple II series can be tweaked to output such signal. I think one day I'd love to see a nice and crisp picture out of it!
As usual, I made a video of the repair. I made sure I quoted this forum and also explained that my "theories" were coming from this forum! :) Feedback is as always welcome!
https://youtu.be/l-cLiZzBxhw
Oh, I'm also adding here my final ROM bin file with all the ROMs concatenated together. This works with the Rom Replacement you can find here: https://www.blue-print.be/
Me again :)
Not unexpectedly for a 40-yo machine which has been in storage for decades, the Apple II Europlus has failed again. In a similar manner.
After a power cycle it would not auto-start. I moved the controller to slot 7 and it would auto-start again. I thought the same IC had failed again so I replaced it but that did not fix the problem.
This time:
- The floppy drive only works from slot 7
- If in any other slots, the computer hangs on APPLE ][. If I hit reset and type PR#6, the drive DOES NOT spin! If I remove the controller altogether, the computer drops me to Applesoft as expected.
- If I check the ROM with C700L etc, the controller is being seen in the slot it's plugged in but NOT in the others as expected. So when the controller is in slot 6, I see the controller ROM on slot 6 but NOT on slot 7.
So the slot selection seems to be working this time. But the computer cannot drive the floppy drive unless it's in slot 7. I'll try to educate myself and find the cause but if anybody has any ideas, please do let me know :)
Thanks!
=> UB2, SN74LS154.
You verified that the slot ROMs work. That's the "IOSEL" decoder (UB4, LS138). The I/O registers of the slots are addressed through a separate address decoder (UB2). So this would be a usual suspect, which could cause the issue you describe.
Thank you!
I'm looking at schematics but either I am misunderstanding them or I've got the wrong ones! :)
Any chance you mean UH2, 74LS138PC?
I'me reading the "understanding the Apple II" and I see the two selection logic. UH12 is the one I replaced which looks after the "I/O select", UH2 looks after the "Device Select" signals. Very interesting!
Yes, sorry, I had the Euro IIe schematics. On the II(Euro)+ it's UH2, 74LS138 driving the device select lines. Try replacing this one...
Shall do, thanks for the suggestion! :)
If it's the UH2, it would be very weird to have two separate faults causing a similar issue on the same machine! :)
Well, they were probably twins. Same type, probably made in the same factory and from the same lot. Worked together in the same machine, doing the same kind of work (address decoding, always running at full clock speed). If one of them decided it has had enough, the other is probably just as tired... :)
I still need to look into the Apple II - might do that next week - but I'd like to understand what the difference is between the I/O select line and the Device select line?
Each slot has two address ranges. For slot s=1..7:
The Disk II Controller card uses both.
Understood, thanks!
Back to the video signal of the Europlus, I still have a question. I thought the Europlus was an NTSC Apple II+ with 50Hz refresh rate? I could see the NTSC colour burst on my oscilloscope. I read it's a "BW" machine and I thought it's because a PAL monitor cannot interpret the NTSC colour burst. But none of my capture devices seem to be able to show colours on it and they should be NTSC compatible.
Is that because of the refresh rate? Or simply because the signal is too "weird" for the capture device to display something? In other words, would I get colours if I used an appropriate colour CRT?
Thanks!
The Europlus is switched to 50 Hz using the circle and bow tie pads (as I already mentioned above), but on top of that they also changed the crystal from 14.31818 MHz to 14.25045 MHz, which is not a whole number multiple of the NTSC color subcarrier frequency 3.579545 MHz or any other standard color subcarrier frequency. Because of that it doesn't fall into any of the composite color standards and no TV (or other device) will see it as a valid color signal.
I would switch it back to NTSC if I were you. By doing that you will be restoring it to a more original form, not less. One of the most amazing things about the Apple II is that it had color when it came out in 1977. This is what the people in the museum will be seeing on a good color CRT monitor:
TotalReplay.jpg
Thank you, now I understand!
There is a component of keeping things as original as possible there as you can imagine. If the Europlus was a BW machine, then I suspect it would be the museum's intention to show it as it would have been in the '80s. If a Colour machine is needed, we have plenty of Apple II+ and also Apple //e which could be restored and displayed to the public.
For now we have an original Apple Monitor II which is monochrome - the Apple colour monitor was designed for the /// and while it used to be sold as monitor for the Apple // series, it "doesn't look right" on top of an Apple II machine.
Anyways, it's good to know there are options. But if colours were needed, I think I would rather restore a proper Apple II+ instead - that should be a native NTSC machine, right?
(We do have TWO Apple /// monitors, one still has the mesh cloth on it, the other was removed. The one with the mesh looks amazing - even though I can imagine the picture quality was compromised by years of dirt!)
IMG_7257 (Medium).jpeg
If it comes from the US - yes. But if it was originally purchased from the UK (like mine Apple II+ was) it might not say Europlus anywhere, even though it is. The sure way to tell is to look at the circle and bow-tie pads on the motherboard or the frequency written on the crystal.
ah, understood.
I feel that if colour is needed, an Apple //e is the solution :)
In any case, I would need to restore one of those two Monitor /// first before even thinking about colour!
It was indeed UH2, thanks for the help again!!
Now off to mod the ROM :)
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