8mm Forum: Yashica vs GAF

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Posted by Patrick McGrath (Member # 1210) on December 20, 2008, 12:18 PM:

Hello all,

For some time now I have been tinkering with my Yashica P810, trying to get it running properly and I believe I have finally achieved some measure of success.

I have been through several modes of tinkering including trying to get the sound from making popping noises(which turned out to be worn brushes and springs on the motor, causing excessive sparking) to getting the motor to run at the right speed to rebuilding the speed control(this part remains unresolved and a bit of a mystery).

I have not completely resolved all three, but I have been able to view film through it and I am very pleased.

The topic title has to do with a machine I picked up inexpensively and quickly brought back to life but ultimitely sacrificed(you might call it projecticide!) for the Yashica.
I found a GAF 3000s at a swap meet and gave it a good cleaning and thorough inspection and was using for a brief period of time, all the while still set on restoring the yashica.
After running some film through the GAF I couldn't help but feel that I might be risking my films(the few that I own in my burgeoning collection). The overall construction just struck me as cheap. Lots of plastic rollers with sharp edges and a plastic pressure plate among other things.
Well, the end came when I scratched my newly acquired print of the Ken Star Wars 400 footer. It was pristine, except for a brownish color hue, and a stuck roller put two nice scratches in the first five minutes of the film. They don't last but a minute or so each, but heartbreaking none the less.
That was my cue to get back to the Yashica. I took the motor out of the GAF and put it in the Yashica as I had ruined the original motor while taking it apart trying to discover what was wrong...live and learn...and I did learn a lot about electric motors and how fragile things like balance are to them!
Then I got the motor to run at the right speed by a trial and error method of finding the correct resistor value for 24fps(happened to be 20ohms 25w).
As stated the actual speed control remains a mystery. I swapped out every part except the diodes which were doing their job of converting the voltage, and still no luck, hence the resistor shortcut.

In the end, as compared to what I was seeing with the GAF, the image on the screen is miles above, as are the internal workings.
The GAF uses a DNE bulb which is 150watts, but as I learned the EFP bulb in the Yashica(halogen 100watts) is so much brighter.
The lens is also no comparison. A much sharper, precise focus is possible, print quality notwithstanding of course. Overall I feel as if I have a real professional projector, not a toy.

Anyway, just thought I would share my excitement of finally having accomplished my goal.
And the good news is my brother-in-law found another identical machine(in Japan) that is 100% operational, so I will have a second for change-over and I can reverse engineer a working speed control and maybe restore this one completely!

I don't know what's more fun, the tinkering or the showmanship.

Posted by Osi Osgood (Member # 424) on December 20, 2008, 11:26 PM:

Congratulations Patrick!

I still have yet to even pull out my Yashica yo get it to work.

If you could be so kind, could you send some good advice so that i can at least get er started!

Posted by Patrick McGrath (Member # 1210) on December 21, 2008, 09:06 PM:

I seem to recall you had my original problem of popping sounds, correct?
My recent experience points to the brushes and springs being the culprit. It seems that the brushes wear out some and the springs don't push them up against the motor armature as strongly, thus creating excessive sparks which cause noise through the speaker.
My first repair(sure, NOW I know this!) would be to replace the springs and/or the brushes. If you can find some springs with a little more tension that may be all you need.
If your speed control is a problem, well, I can't help you there. Not yet anyway...

Posted by Dino Everette (Member # 1378) on December 21, 2008, 10:44 PM:

Aha!I knew there was a reason I leave my GAF 3100S in the storage - You just saved me and some film as i was "this close" to pulling that sucker out and giving it another shot - but it will now remain potential display pile for when and if i ever get that room to display projectors anyhow.
Cheers

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