Re: Apple ][ transistors and crystals.

["Michael J. Mahon" <mjmahon@aol.com>]

MdntTrain wrote:
> Recently went searching for replacement 2N3904 and 2N4258 transistors
> for Apple II board repair.  2N3904 still easy to find but the high
> speed 2N4258's are gone.   Found one suitable replacement in the
> NTE106.   I have data sheets for all 3 in case anyone wants them.

Its specs are not very critical, as long as it works in the crystal
oscillator circuit.  A "better" substitution should be fine.

> Also looking for a 14M crystal replacement.   I see that they come in
> at least 2 "LOAD" types called "series" and "20pf standard".    I'd
> like to know what this LOAD parameter is, and what's the correct
> choice for the II motherboard?

The Apple II crystal oscillator does not use loading capacitors, so
use the "series" type.  The crystals are actually identical except
for a very slight change in frequency depending on loading.  The
wrong type would result in the Apple running fine, but the color
subcarrier might be off enough to cause no color in a composite
display.

-michael

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