This is topic Problem with CP500D Volume knob. in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by Demetris Thoupis (Member # 833) on 07-25-2002, 12:32 PM:
Hi all,
Long time no see. I seem to be having a problem with one of the theaters I am working in. On the DOLBY CP500. The problem is that both a clockwise and an anticlockwise rotation of the volume knob leads to an increase in the volume instead of a decrease. Can someone give me a clue what is the problem and how can it be solved?
Thanks all.
Demetris Thoupis
Posted by Chase Taylor (Member # 778) on 07-25-2002, 01:52 PM:
We had the same thing happen to use. I don't know what they did to fix it because it was under warranty and they just sent us a hole new front for the CP-500. We just swaped them out. Moral to the story is Call Dolby.
Posted by Ken Jacquart (Member # 369) on 07-25-2002, 02:10 PM:
Your shaft encoder has a problem... you will need to order a repair/exchange of a CP500-FP (front panel). Just call your service company/dealer with that information and serial number of the unit...ken
Posted by Steve Guttag (Member # 268) on 07-25-2002, 05:23 PM:
It is either the shaft encoder or perhaps an evil software download by a film producer to prevent theatres from lowering their volume levels 
The shaft encoder has two output that form a quadrature pulse. If one is stuck high or low and the other one still functions, the decoder will interpret this as to go in the one direction.
Steve
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"Old projectionists never die, they just changeover!"
Posted by System Notices (Member # 2357) on 04-26-2013, 09:31 PM:
It has been 3928 days since the last post.
Posted by Reed G. Hinton (Member # 1852) on 04-26-2013, 09:31 PM:
How do you remove the knobs from the Dolby CP500 and also, how do you remove the knobs from the Dolby CP65? I want to take them off so I can remove circuits and clean. Thank you. Reed G. Hinton
Posted by Tony Bandiera Jr (Member # 2365) on 04-26-2013, 10:34 PM:
Hi Reed:
The short answer is you do not remove the knob from the CP500. The encoder is easy to damage and new/exchange front doors are very hard to come by. Use anti-static canned air to blow dust out of the fans, off of the circuit board and around the knob.
On the CP-65, carefully pry out the center cap of the fader knob. There is a nut under there that you loosen and carefully pull the knob off. Then pull the silver detent "sub-knob" off. The actual pots in the CP 65 are sealed and cannot be cleaned.
BTW your cables will be heading out tomorrow. ![[Smile]](smile.gif)
Posted by Louis Bornwasser (Member # 3063) on 04-27-2013, 06:00 AM:
I have shaft encoders for cp500 in stock. Yes, if you are careful, they can be changed out. Louis
Posted by Ken Lackner (Member # 1002) on 05-02-2013, 08:54 AM:
Louis, are those after market parts? I thought Dolby only offers the entire front panel.
Posted by Louis Bornwasser (Member # 3063) on 05-02-2013, 09:25 AM:
That is correct, now, but I did purchase encoders from Dolby back then. They have repaired the problem every time I swapped them. Also have fans. (Sometimes the display is OK.) Louis