Film-Tech Forum ARCHIVE: (RESOLVED) Little help on BACP RSTR-2000 optical reader

This is topic (RESOLVED) Little help on BACP RSTR-2000 optical reader in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Monte L Fullmer (Member # 2797) on 11-04-2008, 04:17 PM:

K, here's what I got: 5 star head with this reader inside. Doing an "A" chain on this thing.

Why of the "A" chain is that I'm getting a horrible buzz in center channel.

Guess what? the trimpots in the CAT 240 preamp card in this CP-55 processor were turned up all the way, thus figuring this is where I'm getting that buzz (feedback) from. And I can't even get dolby level with CAT-69 tone loop.

Scope shows X/Y alignment to the proper diagonal.

Snipped the jumpers to get me more gain. After the snip, managed to get my Dolby levels, but only by turning down the trimpots two turns counterclockwise. Thus still have my buzz, but not too bad. I turn down the pots to rid of the buzz, but optical is way too quiet for optical playback.

Figuring that the LED is getting weak (6 yr old readers) after checking camera optics if they were clean. What is the duration on these LED's anywho from BACP?

Oh, forgot to mention: On the wiring from the Phoenix plug to the processor - the minus wires on the Phoenix plug and on the processor are jumpered together. Is this an acceptable wiring, or do I need to make the minus wires separate for L/R connections?

thx for the help - Monte

Posted by Jeremy Weigel (Member # 4208) on 11-04-2008, 06:08 PM:

quote: Monte L Fullmer
Figuring that the LED is getting weak (6 yr old readers) after checking camera optics if they were clean. What is the duration on these LED's anywho from BACP?

I was wondering this myself. I've had to replace 3 of them and they were less than 4 years old. I use the supplied PSU plugged in to a relayed outlet so they only burn while the projector is running. Also, is there any core exchange program for the spent LED's or do just save 'em up and turn them in for the copper?

Posted by Gordon McLeod (Member # 33) on 11-04-2008, 06:11 PM:

I use a 2 pair shieded cable between the reader and the processor

Posted by Monte L Fullmer (Member # 2797) on 11-04-2008, 06:19 PM:

Thx, Gord on that - for I was wondering that myself why this one head wasn't wired with 2pair shield per each channel.

quote: Jeremy Weigel
I use the supplied PSU plugged in to a relayed outlet so they only burn while the projector is running.

You'd think that with your PS wired on a switched circuit that the LED should last mega times more as long if stayed on all the time.

-Monte

Posted by Scott Norwood (Member # 30) on 11-04-2008, 06:19 PM:

I put in a pair of these over the summer (yes, this summer!) and found that there was enough play in the way that the LED mounting bracket attached to the 5-star that tilting it slightly (either up toward the projector head or down toward the holdback sprocket) would affect the signal level. You might try loosening the three screws and adjusting it for maximum signal.

No idea on the hum, but there's an optional jumper on the Phoenix connector that you can try (see the manual). Does the hum go away if the reader is disconnected?

I don't claim to be an expert on cables, but I have used Belden 8451 and 8723 in two different setups and had no issues. These are the 2-conductor shielded and 4-conductor shielded cables, respectively, that the Dolby manual recommends. I've also used Canare L-4E6S star-quad (intended as microphone cable) for a temporary setup and that worked fine, too.

Posted by Sam D. Chavez (Member # 1841) on 11-04-2008, 06:52 PM:

The LED life is usually 3 years or so before needing to clip the gain jumpers. The BACP reader was designed such that you will obtain 8 dB over Dolby Level with the preamp trim pots turned full up. This means of course that the LED can dim by 8 dB before needing to cut the gain jumpers.

This presumes the LED is in the exact center of the sweet spot. The green signal presence LEDs can be used while swiveling the LED bracket while running a loop of Dolby tone or other steady state audio level for brightest output.

There is a repair exchange program on the LED modules. The most common module is RSLH-2, except for the Cinemeccanica which is RSLH-3.

The audio cable absolutely needs to be two pairs of shielded cable like 8451 or 8723 with the shield tied down at both ends.

If you are running into a mono system, you should common the Left and Right minus and Plus should be done at the receive end.

Posted by Jeremy Weigel (Member # 4208) on 11-04-2008, 07:12 PM:

quote: Sam D. Chavez
The LED life is usually 3 years or so before needing to clip the gain jumpers.

Ah, that was another thing I was wondering about. Why not make those jumpers the removable 2 pin type so when a new LED is installed the jumper can be more easily reconnected?

quote: Sam D. Chavez
There is a repair exchange program on the LED modules. The most common module is RSLH-2, except for the Cinemeccanica which is RSLH-3.

I will definitely check with UCS on this again. When I replaced my LED's I was told there was no repair/exchange program.

Posted by Monte L Fullmer (Member # 2797) on 11-04-2008, 08:39 PM:

Changed out that dumb cable to the right cable and that really did help out on the output, and got rid of that buzz.

Still though, the LED does act weak since I got Dolby level, but the trimpots are still almost to the extreme, thus have to make arrangements (Sam, how do we make the exchange arrangents for the LED assembly?) for a changeout in that area.

Thx all for the help. I changed the topic title since I got my problem taken care of.

thx again -Monte

Posted by Andrew Bangs (Member # 4938) on 11-05-2008, 01:56 AM:

Does anyone have a picture of the LED Assembly? I am wondering if this might be what I have or at least similar to it as the description so far sounds dead on. Our theatre is about three years old now so I think our LED's might be up for replacing. I am having all sorts of Audio Drop out in different theaters.

(Edit) well this is not the unit I have but the life expectance still sound the same. Three yeas on one LED.