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Author Topic: Dead LP-270
Dominic Espinosa
Phenomenal Film Handler

Posts: 1172
From: Boulder Creek, CA.
Registered: Jan 2004


 - posted 11-06-2008 06:12 PM      Profile for Dominic Espinosa   Email Dominic Espinosa   Send New Private Message       Edit/Delete Post 
So this afternoon I come in to open up one of our theaters and find that whomever closed the night before had depressed 2 of the 4 mode switches for the bottom platter on one of our LP-270's.
I managed to push/pull/wiggle one of the switches out, all switches now depress and pop out as they're intended.
However, the platter was completely dead. I checked the fuse under the select switch cover which was fine however the 5 Amp fuse in the bottom of the column was blown.
Swapped it out but it just popped again.

My thought is that the contacts inside one of the buttons is still engaged. Thoughts?

EDIT: Did some searching -- could this be a diode issue resulting from the button press?

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999


 - posted 11-06-2008 06:58 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
Yes...all but the most old platters use an octal plug with either 4 diodes inside or a square-pack bridge rectifier mounted in the octal socket.

Another possibility is that the switch bank in question remains bad and is causing a short circuit. I'd start with the bridge rectifier though.

Steve

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Monte L Fullmer
Film God

Posts: 8367
From: Nampa, Idaho, USA
Registered: Nov 2004


 - posted 11-06-2008 11:35 PM      Profile for Monte L Fullmer   Email Monte L Fullmer   Send New Private Message       Edit/Delete Post 
I ran a booth with four LP-270's and had two that would love to blow the fuses which did turn out to be that plug-in diode would be shorted.

Never could figure out why of the diodes would short out unless we had some crazy voltage come swinging into the building.

One changeout and it'll behave for good on one unit, while the other unit would take out a diode set twice or more in a year.

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Dominic Espinosa
Phenomenal Film Handler

Posts: 1172
From: Boulder Creek, CA.
Registered: Jan 2004


 - posted 11-07-2008 02:07 PM      Profile for Dominic Espinosa   Email Dominic Espinosa   Send New Private Message       Edit/Delete Post 
Interesting. Thank you both for the input on this situation.
We ended up getting back up after I called our resident guru who has had more experience with these than I and happened to have a spare diode stashed at the theater.
I had assumed we didn't [Wink]

Interesting on your note, Monte, we had a power outtage 2 days ago -- wonder if that contributed to this issue as it did cause a small amount of havoc with our computers -- or so I'm told...

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999


 - posted 11-08-2008 07:59 AM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
If you want to virtually eliminate the diode failure, try putting a suitably sized MOV across the AC input to the bridge.

Steve

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