Film-Tech Forum ARCHIVE: DTS LED voltage

This is topic DTS LED voltage in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Richard Tucker (Member # 812) on 07-20-2003, 11:47 PM:

I replaced some old DTS readers about 8 months ago, and I am having to go back already and adjust the LED voltage. Some of these are now maxed out on the pot, and a few won't even come up to 4 volts. Anyone else having this problem? Did DTS get a bad batch of LED's? And is it possible to change these LED's in the field?

Posted by Darryl Spicer (Member # 711) on 07-20-2003, 11:57 PM:

I would probably get with DTS and explaine the problem to them and try to get another repair/exchange on them. If you mess with them and screw something up they may charge you for a new reader.

Posted by Tim Reed (Member # 137) on 07-21-2003, 08:05 AM:

DTS readers are adjustable?

Posted by Aaron Sisemore (Member # 145) on 07-21-2003, 02:41 PM:

quote:
DTS readers are adjustable?

Yes, they are.

There is a procedure to reset the LED voltage to compensate for LED wear and subsequent mistracking of the timecode.

I used to have a PDF file with detailed, warranty-safe (Karen's hands in the pic doing the example adjustments!) [Smile]

instructions on how to accomplish it. IIRC, it worked with a certain version and above, the early readers cannot be adjusted and would need to be returned for repair/exchange.

Ask Karen for the LED voltage adjustment instructions.

-Aaron

Posted by Antonio Marcheselli (Member # 373) on 07-21-2003, 04:06 PM:

You can download DTS led adjustment procedure on the DTS site on the Techcenter section.

Bye
A

Posted by Manny Knowles (Member # 1171) on 07-21-2003, 08:49 PM:

You mean we don't have them here on F-T?
[Confused]

Posted by Brad Miller (Member # 2) on 07-21-2003, 08:56 PM:

It's in the queue to be added and is an important thing to check that most people don't know about.

Posted by Tim Reed (Member # 137) on 07-22-2003, 12:39 AM:

Humm... that must've been something that happened after I left the service biz.

Posted by System Notices (Member # 2357) on 09-19-2004, 05:50 PM:

It has been 425 days since the last post.

Posted by Bruce Hansen (Member # 281) on 09-19-2004, 05:50 PM:

BTW, when making this adjustment, do not shine a bright light into the reader while making this adjustment. The light can shine on the cell, and effect the reading. (been there, done that).

If you are having problems getting 4 volts from the test point, try cleaning the LED, the lens, and the cell (remove the board from the reader, the cell is on the back of the board).

...And BTW, the pot adjusts the gain of an op amp, not the LED voltage. You can prove this by tracing the board traces. The LED is fed by the power supply through a fixed resistor, the pot is connected to the op amp.

If you want to look at the output of the reader, but do not have the special cable, if you have the back off the reader put your scope probe on the upper lead of R-5 (the lead that faces the pot).

Posted by Mark Gulbrandsen (Member # 72) on 09-19-2004, 05:59 PM:

Also be sure there is no film threaded through the reader.

MArk