Need help with parts for LaserWriter IINT printer

[brown@vidiot.UUCP (Vidiot)]

Since Apple has this real stupid idea that user's can't fix their own equipment,
I am unable to order a couple of itty-bitty parts from Apple.  Unlike other
consumer and professional gear, service manuals can be purchased, as well as
parts.

I recently tracked down a problem with my LaserWriter IINT printer, whereby
it would go into paper out mode, when there was definately paper in the unit.
It was also heat related.  I thought the problem was located on the other
board on the bottom of the printer (other meaning not the main circuit board
that can be extracted without opening the case).  But that wasn't it.  With
cool spray and meter in hand, I tracked it down to the simple circuit board
that is on the right-front side that contains the photo-sensor parts for the
manual feed paper insertion signal and the paper out signal, as well as a
selenoid.  The circuit appears to be an "open collector" type of circuit,
whereby no paper causes the transistor to conduct and pulling the voltage
to ground.  When there is paper, the transistor turns off and the volatage
floats past the threshold.  But, in my case, the photosensor is providing
a false signal to the transistor or the transistor is conducting all on its
own.  Cool spray makes the parts work OK for a very short while.

Because I can't get a scope probe on the circuit board, I can't check to see
which part is bad, so I would like to replace both.

If you know any details on the types of parts that I am after, please send
me e-mail with details on what replacement parts I can get for the current
Japanese marked pieces (do send e-mail since I do not read this group).  The
part numbers on the ciruit board are Q303 and PS301.  The transistor also
has the following markings - C1815Y.

I currently have the printer operating by having the pin pulled, causing the
signal to float high permanently.

Thanks, all help in fixing this thing will be appreciated.

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