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Author Topic: Keystone Zoom 2500 repair question
Michael Korchonnoff
Junior
Posts: 2
From: Silverdale, WA, USA
Registered: Feb 2019


 - posted February 26, 2019 10:40 PM      Profile for Michael Korchonnoff   Email Michael Korchonnoff   Send New Private Message       Edit/Delete Post 
Hello, I am new to this forum. I have recently acquired a Keystone 2500 projector in very good condition for a very modest price. While everything seemed to work fine at first, I discovered that once loaded with film, the forward motion is uneven, causing a partial, distorted picture. However, watching the film in reverse motion is smooth and perfect. I suspect there is a problem with the forward wheel as it seems to have play in it. Is it repairable (how?), or should I start looking for a better projector?
Any suggestions would be welcome.
Thanks,
Michael

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Michael

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Janice Glesser
Film Goddess

Posts: 3337
From: Sunnyvale, CA USA
Registered: Sep 2011


 - posted February 27, 2019 01:07 AM      Profile for Janice Glesser   Email Janice Glesser   Send New Private Message       Edit/Delete Post 
Hi Michael and welcome to the forum. I'm familiar with the Keystone 2500 and have repaired and sold several. Unfortunately I don't have one now to refer to...but hopefully I or someone else can identify your problem.

Terminology can be misleading so perhaps you could clarify a few things. You said that, "...forward motion is uneven, causing a partial, distorted picture." Can you explain what you mean by "uneven" and describe what you see as "partial, distorted picture?" The film is stabilized when it enters the gate and advanced by the claw pulling it down one frame at a time by the sprocket holes. Even if the front supply reel is loose it should not make much of a problem after the film enters the gate.

It is possible that the film is losing the upper loop when the film is threaded or perhaps you need to adjust the framer to position the frame from top to bottom. The framer needs to be adjusted every time you change the film gauge.

Pictures or video are always helpful when trying to troubleshoot a projector problem. It might be just something simple.

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Janice

"I'm having a very good day!"
Richard Dreyfuss - Let It Ride (1989).

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Michael Korchonnoff
Junior
Posts: 2
From: Silverdale, WA, USA
Registered: Feb 2019


 - posted February 27, 2019 09:25 PM      Profile for Michael Korchonnoff   Email Michael Korchonnoff   Send New Private Message       Edit/Delete Post 
Janice, Thank you for replying to my post. I was trying an old 8mm standard film. The forward play has an uneven speed, it seems that half the time it slows down, whether it is loaded with film or not, like there is some resistance happening there. It is irregular, and I can hear a variation in the sound the motor makes. The images were cropped in normal play, not all of the picture was showing and part of the next picture was showing on the screen, also the image was garbled when it would slow down. What puzzles me is that the picture is nice and even while running in reverse. I don't know much (yet) about film projectors, so I have no idea what the framer is or how to adjust it, but I have repaired many things in my life so I am not afraid to learn and attempt to repair if I know what to do.

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Michael

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Janice Glesser
Film Goddess

Posts: 3337
From: Sunnyvale, CA USA
Registered: Sep 2011


 - posted February 28, 2019 01:15 AM      Profile for Janice Glesser   Email Janice Glesser   Send New Private Message       Edit/Delete Post 
Ok Michael...I understand a little better the two problems you are describing.

(1) First off ... do you have the owners instruction manual? If not...PM me with a request for the Keystone Zoom 2500 Instruction Manual. I will send you a link so you can download it. I also have a YouTube video on the Keystone 2500. It's not the Zoom model, but pretty much the same projector...just some of the knobs and switches in different places.

https://www.youtube.com/watch?v=YjSo892DKms

(2)Problem: "not all of the picture was showing and part of the next picture was showing on the screen" This is definitely the framer needs adjusting. The framer knob is located in the bottom right corner of the front panel beneath the "Run/Still" switch. It should be labeled. Film frames of Standard 8mm are smaller than super 8mm. The framer controls a mask that moves vertically (up and down) so you only see one frame at a time centered on the gate.

(3) Now the motor not running at a constant speed could be for several reasons:

Remove the back cover and take a look inside.

A) Loose motor belt - Check the belt to see if it's loose. Belts get old...they stretch...turn to goo...or get hard and crumble away. Replacing the belt won't solve the motor pulsating...but if you get the motor running smooth again...you may need a new belt too.

B) Bad/corroded switch - If the projector had not been run for several years the switch controlling power to the motor may be corroded, a bad wire or solder joint. This might explain why the motor runs fine in reverse but not in forward. Sometimes just working the switch back and forth several times can remove some of the corrosion and improve the contacts.

(C) Motor Oil - The motor may need some oil also.

(D) Power Cord Check the power cord and socket. If I remember correctly that projector takes place a special 2 prong cord...check it carefully that there are no breaks in the cord and that it's securely pushed in all the way into the socket.

(E) Loose transformer wire - Look for any suspicious wiring going into the transformer.

After you take a look inside report back.

[ February 28, 2019, 12:36 PM: Message edited by: Janice Glesser ]

--------------------
Janice

"I'm having a very good day!"
Richard Dreyfuss - Let It Ride (1989).

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