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Author Topic: BACP DSTR 2000 led current adjustment Jeff Else Expert Film Handler Posts: 125 From: Detroit, MI, USA Registered: Nov 2006 posted 10-13-2009 07:41 PM                     is there any? or do i just need to replace the led's? i can't get dolby tone! p.s. mine is the version for the FP-20  |  IP: Logged Jeremy Weigel Phenomenal Film Handler Posts: 1062 From: Edmond, OK, USA Registered: Mar 2007 posted 10-13-2009 08:14 PM                     Is this a new unit or has it been in service for a while? First make sure the optics are clean as well as the LED it self. If its a new unit and you're not able to get an initial Dolby level (assuming you're trained how to do an A-Chain) then there is a set of jumpers you can cut on the main circuit board on the reader to increase the voltage. If this is a unit that has been in service for a while and was correctly set up by your service tech and he/she achieved Dolby tone without cutting those jumpers, then your LED is probably nearing the end of its life cycle. I am also assuming that you're using the supplied non-variable power supply that shipped with the unit.  |  IP: Logged Michael Schaffer "Where is the Boardwalk Hotel?" Posts: 4143 From: Boston, MA Registered: Apr 2002 posted 10-13-2009 08:21 PM                        You should *always* be able to reach Dolby level *easily* with a new BACP reader. The jumpers are only meant to be cut after the LEDs have exceeded a certain lifespan. On the FP20, it is quite possible that the LED holder is rotated and so the light from the LEDs does not hit the lens properly.  |  IP: Logged Jeremy Weigel Phenomenal Film Handler Posts: 1062 From: Edmond, OK, USA Registered: Mar 2007 posted 10-13-2009 08:39 PM                     quote: Michael Schaffer The jumpers are only meant to be cut after the LEDs have exceeded a certain lifespan. Do you reconnect them when you install new LED's?  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 10-13-2009 09:32 PM                     You could have oil in the lens itself. For I also have a "20" unit doing the same thing. I swapped LED modules from one house to the other and I did get some of my Dolby Tone back up. Thus suspecting I've got a oil filled camera tube that is causing my levels not to be up where they should be. ..and my jumpers have already been cut. All LED units do fade after awhile .. if your system is over 7 yrs old, I bet you could use a replacement LED, or to make it tons more easy but a bit more on the dollar.. some new modules. I wouldn't worry on redoing the jumpers after LED replacement - just adjust your preamp accordingly since the PC board that the jumpers are on doesn't have the exact space to work in. -Monte  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 10-14-2009 01:13 AM                       You all get an A from the teacher. It is however and RSTR-2000 not a DTSR 2000. The card has a DC to DC convertor so the input voltage is not very critical. 9 to 12 Volts is fine. The cutting of the links increases the audio gain of the circuit as well as the background noise by 6 dB. Dolby wanted the electronics to be as quiet as possible, so the gain links were a way to optimize this. The FP20 LED assembly is unique as there was almost no room for the LED so it is held in place with thermal heat paste, and is not plug and play like most other models.  |  IP: Logged Demetris Thoupis Phenomenal Film Handler Posts: 1240 From: Aradippou, Larnaca, Cyprus Registered: Apr 2001 posted 10-14-2009 01:14 AM                     I agree with Michael, Check whether the actual bracket which holds the LED assembly has rotated downwards for some reason (someone aplied pressure or it was not tight enough). The easies way to do it is have Dolby Tone loop running and rotate that bracket until you have the brightest signal level LEDs on the FP20 circuit board. These readers aling like a charm. Demetris  |  IP: Logged Jeremy Weigel Phenomenal Film Handler Posts: 1062 From: Edmond, OK, USA Registered: Mar 2007 posted 10-14-2009 01:19 AM                     I haven't cut any of the jumpers on the 6 units I have. I just replace the LED when I'm not able to reach tone any longer. I would think that if you cut the jumpers just for a faded LED and then put in new ones later it would shorten the new LEDs life or am I thinking incorrectly that cutting those jumpers increases the voltage to the LED? or do they just boost the signal without increasing LED brightness?  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 10-14-2009 04:28 AM                     question: quote: Jeremy Weigel or do they just boost the signal without increasing LED brightness? answer...: quote: Sam D. Chavez cutting of the links increases the audio gain of the circuit LED voltage remains the same... hope this helps If you got tired LED's it's best to replace the entire module. If you take a module out and look at it from the back side, it would be a pain to desolder and resolder the LED back on that ribbon strip. So, basically what Sam is hinting at, is, (for us that have our jumpers snipped) - to make things quieter: redo the jumpers after replacing the module. - Monte  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 10-14-2009 09:57 AM                       There is a little flat screwdriver slot on the LED arm to ease in moving the LED arm. If you need to move the arm, loosen the Philips screws holding the arm very slightly while running Dolby tone and move the arm up and down watching the Dolby tone meter to make sure you are at maximum level It's LED current, not voltage as an LED is a constant voltage drop across it while the current varies. Small but important detail.  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 10-14-2009 12:18 PM                     Just installed a pair of DTSR-20 on my Kinotons, pics to come soon. Minor threadjack if I may: Sam, I need to switch the LED's on those DTSR-20's..which is better: switch before the LED power board or after? (The processor will be on 24/7 and I don't want to run the LED's if I'm not running film.) Back to our regular scheduled program: I second the suggestion by Sam to use the screwdriver slot to gently raise and lower the LED to get Dolby tone. Especially if the loss of level came on suddenly, it means the arm was bumped out of position, a design flaw of the projector itself not the reader. I have had service calls on Kinotons where the solar cell was bumped out of line by ham-fisted operators. If you have access to a RTA and some Dolby CAT 566 Illum. Uniformity film, run that too to make sure the full LED array is still working. Try that before replacing the LED or cutting jumpers. And also re-solder the jumpers after an LED change, it isn't impossible if you're patient and have a fine-tip soldering iron.  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 10-14-2009 12:27 PM                        How does the output on the RSTR compare with a solar cell? What about when the jumpers are cut? I had to cut both in a setup with a Kelmar mono system to approximate the output of the old solar cell (after adjusting the LEDs to maximize output, as described above). This needed to be done for both projectors (changeover booth). Is something else wrong here, or is this normal? I've not cut the jumpers in any setup with a Dolby processor, and can hit Dolby level with no problem, although the cat. 240A has a much wider gain adjustment range than the Kelmar. I've installed a few of these and have not had to replace the LEDs, although all are in venues that run film only occasionally.  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 10-14-2009 12:43 PM                     quote: Sam D. Chavez If you need to move the arm, loosen the Philips screws holding the arm very slightly while running Dolby tone and move the arm up and down watching the Dolby tone meter to make sure you are at maximum level Thx for this tip since some of us didn't know this trick. Dang, where is that old 'filament image on the card' trick when you need it. -Monte  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 10-14-2009 01:35 PM                       The screwdriver slot is only on the FP20 version The LED should be interrupted after the board. As to low output on the Kelmar; there is a solar cell loading resistor across the Kelmar as in most mono systems that is no longer required. Once you do this the output will come way up.  |  IP: Logged Michael Schaffer "Where is the Boardwalk Hotel?" Posts: 4143 From: Boston, MA Registered: Apr 2002 posted 10-14-2009 10:55 PM                        quote: Sam D. Chavez As to low output on the Kelmar; there is a solar cell loading resistor across the Kelmar as in most mono systems that is no longer required. One would hope that mono systems as such are no longer required!  |  IP: Logged

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