Apple II Europlus main crystal frequency, NTSC vs PAL, etc

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Apple II Europlus main crystal frequency, NTSC vs PAL, etc

Hi, according to the Apple II reference manual, the Europlus (50 Hz) model has a different main crystal frequency than the standard NTSC model. I have a Europlus that I want to convert to NTSC, in order to get color output (Europlus video is monochrome if you don't have a PAL video card, which I don't).

I have reverted the X- and O-pad changes, but I'm not sure what frequency the current main crystal is. I think it is labeled something like "197-000"...

So my questions are:
1) what frequency is the main crystal in the Europlus, and in the standard NTSC model?
2) how do I know the frequency of my current crystal?
...and also
3) are modern CRT monitors capable of displaying both PAL and NTSC, or do I need to get a NTSC-only monitor?

Cheers
Jakob

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It is 14.31818 MHZ. However

It is 14.31818 MHZ. However not all 14.31818 MHZ crystals are the same. You need a series resonant crystal. Even then, not all series resonant crystals will generate the correct frequency in an Apple II circuit. For an Apple II to generate correct color burst, the only part that I have found that consistently works is Vishay/Dale part number XT9UNLANA14M31818. This is available from Mouser (part number 73-XT49U1431-S).

There are two ways to tell the frequency of your current crystal. Look up the manufacturer and part number, if you can find it on the part and see what it is specified to be from manufacturers data sheets. If you can't find a manufacturer and part number, you could use a precision frequency counter and test it in circuit.

I had a Euro configured Apple at one time and one of my NTSC monitors could lock onto it's signal, though in general you'll have trouble getting good vertical lock with many NTSC monitors when it trys to decode a PAL signal. Also, PAL configured Apples don't support color without an extra PAL board that plugs into slot 7.

Regards,
Mike Willegal

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I can confirm that also C-MAC

I can confirm that also C-MAC's HC49 crystals work, even though they appear to be parallel resonant devices. I tried one today in my Apple II, and it works like a charm. I finally get colors on my monitor! (I had a PAL crystal before)

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Color!!

I'm afraid I didn't understand well... Do you really mean that if I replace the crystal of my PAL Apple II Europlus, I will have a fully coloured NTSC computer??

WOW it would be great Biggrin

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You also have to change a cou

You also have to change a couple of connections on the motherboard. A PAL configured motherboard has a few opposing triangles on the motherboard near location C-14 that need to be connected and some opposing circles that need to be disconnected for NTSC. PAL boards have the triangles separated by cuts. You can use a small wire and some solder to reconnect. PAL boards have the opposing circles connected with blobs of solder. Use solder wick and a soldering iron to remove the solder.

Rev 0 boards do not have this easy modification built into the PCB.

I wonder why they didn't use jumpers for this configuration change as it would have simplified the change from NTSC and PAL. The crystal needs to be changed out, as well, so I guess it doesn't matter.

There are similar places on the firmware card PCB that can be altered to make it compatible with 2716 eproms.

Regards,
Mike Willegal

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Re: Color!!

I'm afraid I didn't understand well... Do you really mean that if I replace the crystal of my PAL Apple II Europlus, I will have a fully coloured NTSC computer??

WOW it would be great :D

As Mike says, yes you can do that, but you also have to undo the 50 Hz mod, as i wrote in my first post : "I have reverted the X- and O-pad changes"

This is an easy way to get color from a Europlus (without using a PAL encoder), since most modern TV sets, it seems, can handle both NTSC and PAL video input. My TV switches automatically.

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BTW if anyone's interested, I

BTW if anyone's interested, I measured the frequency of the Europlus crystal. It seemed to be around 14.238 MHz, as I recall.

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The PAL horizontal frequency

The PAL horizontal frequency is 15.625.

The PAL crystal should be 15,625 * 912 or 14.25 MHz.

This info is from an old usenet (comp.sys.apple2) post

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Re: The PAL horizontal frequency

yes this works I've done it.

Smile

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Re: Apple II Europlus main crystal frequency, NTSC vs PAL, etc

Hi, resurrecting an old but important thread (for us in PAL-land! )

i have an apple ii europlus, with a 16k language card, 80 col card, serial, disk controller cards only. ie no colour cards

I have changed the crystal as noted

I have made the triangle pads 12 and 16

cut the circle pads 13, 14, 15

I have a stable display, but is still black and white. my NTSC motherboard iie shows color on the same cable and monitor.

are there any adjustments on the board you can point me to?

failing that, do I need to find a suitable crystal? i cannot presently find the right one here in Uk - mouser dont have stock and i've tried 2 types so far.

thanks for any help! Smile

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Re: Apple II Europlus main crystal frequency, NTSC vs PAL, etc

Mike very kindly helped me with a crystal, as described in the earlier post, and after checking those pads cut/made.

it works! NTSC color restored. NTSC 3.58 says my LCD TV.

thanks Mike!

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