I am seeking for someone who would be interested in beeing part of the VNB-DB development for the Barco 909, since I don’t have such machine, but would be nice to catch that market as well So obviously the applicant should have a Barco 909 and basic/advanced electronic knowledge, and general knowledge about the 909 operation. I can do most of the design of the interface circuit between the Barco and VNB-DB, but without a machine to test in I’m pretty sure it won’t work for the first trial, so the applicant would have to correct these errors (with my support of course), this will most likely involve soldering, taking measurement with oscilloscope etc.
BTW, the total cost of ownership of the VNB-DB for Barco would be like this: +65€ (or 70 USD) for the additional power supply for the VNBs +280€ (or 300 USD) for the VNB-DB +0-30€ (0-34 USD) for the interface board: I’d try to make out the interface board with cutting my profit ie. no additional cost, if it won’t be very expensive in parts (which I hope) +Whatever the market price to source Electrohome VNBs.
For the applicant I’d give all this for free (incl. the VNB)
BTW2, Would this be appealing to Barco 909 owners with these conditions at all?
He could be indeed, but I need self appliers as I don't want to push anyone into things they don't want.
Anyway, the needed modifications don't look horribly difficult by the first sight: - the contrast signal should be good as it is - the brightness controll also seems easy, but I don't know what voltage range the controll signal varies in the 909. - the clamping pulse needs verification, but seems usable as it is. - blanking seems ready to use - spot kill needs verification - the OSD/source switch signal needs to be inverted in voltage - the OSD signal needs more attenuation as I saw. - the G2 controll circuit have to be substituted, this would be easier with abbandoning the ABL feature (is the barco let to set G2 manually?)
Don't think I am a time millionaire As far as I saw your language is not worse than mine. Time frame? It will happen when it happen, I am already late with CRT mods, the stakes are not very high: we can sell 2 mods or 1, more likely it is just fun. For me it would make me glad if my mod would make the owner happier.
O.k got it, I sure feel addressed but I want to be sure I can do it because I have a lot of things going on and don't want to waste your time. Also don't want to steal this opportunitie from anyone else ,although there seem not to be much takers (yet).
I attached the schematics of both the Electrohome VNB and my design.
The VNB's most attractive property is that it can be fully driven only with 0.7V input signal and its design inherently allows super bandwidth, so basically not much preamplification is needed. My design is based exactly on this advantage.
A detailed description about the VNB you can find in the service manual section of this site, but in a few keywords: -The VNB has a spot kill feature +5V kills the beam current (internal pull up resistor also included) -The VNB has internal brightness controll, with +/-2.5V controll range, also this is paired with a clamping circuit, to minimalize circuit /input level drift. -Has a proportional current sens output and an over current detector. -Needed supply lines: +/-85V (for end stages), +/-15V (for auxiliary circuits), +/-5V (for low level circuits including high freq. circuits)
Let's my design: It still uses the good old AD835, but in an unusual application. The whole thing is centralized around the fact that the AD835 has an output function of W=X*Y+Z. The video input is directly tied to the input Y, the contrast signal is fed to input X, at input X there is an analog switch, that can toggle between the contrast voltage (normal operation) and the ground (blanking the input). Then there is the Z input where again there is an analog switch, that is toggled between the OSD/testpattern signal source and the ground.
-During normal video, the contrast voltage is fed to X and Z is grounded. so the OSD/testpattern is bypassed. The analog switch might have a crosstalk, but even then it is conducted down to the ground through its Rds(on), so in fact a quite good rejection is achieved this way. The output therefore is: W=Y*X+0 -When OSD/test pattern mode is on the X input is grounded (aka. muted video input) but the Z (OSD) signal is let through ie. W=Y*0+Z. -During blanking the Marquee switches back to OSD source and injects blacker than black level through the Z input (OSD), this however may not be the case with other projectors, so an optional blanking circuit was also added to the design "just for sure".
The AD835 when properly used has about -60dB rejection to the input signal when it is multiplied with 0, on the other hand the dynamic range of each color is only 48dB (as it has 8bit resolution)
However in this way the OSD/test pattern is not affected by the contrast setting, but I don't think this would be a real problem.
So all needed feature was done only by playing around the AD835, but nothing was put in the video path, only the AD835, but you can't omit that, since some sort of contrast controlling is needed anyway...
The AD835 is slew rate limited by the first hand, that means high output voltage cost a lot of bandwidth, on the original 02p VIM therefore the output was not even properly terminated for the 75Ohm transmission line, still about 25% signal loss occuring on the coax cable through the VNB. By putting this small board right at the VNB you gain this 25% signal level (that translates to bandwidth overhead), and the input level requirement is still the same.
With this circuit I measured around 1,5ns rise/fall times at 0.7V output (1 pixel at 1080p 72Hz is 5ns wide) which is still plenty fast.
There is a separate low noise +/-5V power supply for each board that also feed the adjacent VNB's +/-5V line too.
The gamma correction is also "interesting" for the blue. With these multipliers used in CRT applications it is often overlooked that all inputs are actually high bandwidth capable, So unlike to the VIM the gamma is not added to the output signal as a serial element.
he gamma is what gave me the most headache... As I saw from calibration curves is that the blue drops the high end with linear drive. So I aimed adding more gain dynamically based on the input signal. The first version was a simple comparator so under the threshold level the gain was A over the threshold the gain was B, but as turned out this is not really what was needed, the second trial was to linearize the comparator so it would give a proportional output to the input signal (the higher the input the more it „push”), this was far better but then it turned out that at high frequencies like 1080P 72Hz the comparator introduced quite some lag in the signal, so the input signal was at it s peak with a single pixel, but the gamma generator output was lagged by several nanoseconds, so it was actually modulated the gain in the wrong way, with slower signals it tracked fine at least. There were other problems though. The correction waveform and the contrast singnal was summed at an emitter folower’s base, being that way the summing was carired out by changing the ratio of the resistors on the base, this was double bad on one hand the resistance needed to be as low as possible, but still needed to be around 1k from the corrector circuit, the other bad was the gamma rate was seriously interacted with the actual contrast setting. You set the gamma rate and your contrast went away as well and vice versa.
To overcome these problems active summation was made thereafter, knowing the input of the multiplier is X=(X1-X2). Unfortunately the contrast and the gamma signal have to be added not subtracted. Fortunately the multiplier knows elementary math well: Gamma-(-Contrast)=Gamma+Contrast. Obviously I chosed to invert the contrast signal which is a quasi DC signal anyway, rather than the precious gamma signal. With the newest solution the gamma curve is derived by a simple voltage divider from the input signal (no lag), since the impedace was kept at quite low level we don’t have to care about frequency response either (I tested a 200 Ohm SMD trimmer before that did not affect the bandwidth at any setting in an 50 Ohm terminated system even without added peaking) and here the resistance even smaller by an order. This way gamma and contrast signals are not interacting.
After all it turned out this gamma concept is essentially the same as what was made in the Barco 909 -which I did not understand for a long time how/why is it working… It is a popular trick to disable the gamma on those barco boards but there the input derived signal was switched by conventional multiplexers, with only 4 fixed settings and even the resistance wasn’t kept at a very low levels so they had to peak those dividers, also in the barco the gamma is made in a separate AD835, that made a difference in signal chain integrity between green and the other colours as well.
Happy to help out with this one if know one else has the time or equipment. I have done a lot of playing with the Barco and I don't want to take this opportunity away from others. It's a lot of fun modding and learning what does what. I was going to work with the Sony 1292 as its already set up in the work shop, but it's easy to swap over to the 909 and start taking measurements. If know one else is keen I am in.
Nice! It seems a group is getting together, this is good! In fact this even could be an open source project as well. I mean I gladly do the design job for the "converter board" and make it fully open source afterwards based on your measurements, so anyone could reproduce the board. I did not hide much with the VNB-DB so far either, except for my PCB layout, that I still want to keep for myself however (but I sell the blank PCBs cheap anyway) Nevertheless, when the project gets mature enough, obviously I'll need tester(s), now if we are groupping up I can't promise to everyone a free set of VNB, but we'll work out something so everyone should be pleased in the end.
Then let's start the work... As a foreword I also want to add that I am not necessarily sticking to use the Electrohome VNBs, because it may cause great inconvenience in the end to dial in every little details to make it fully Barco compatible. So, I see a very little chance also for combining the VNB-DB, or a similar daughterboard to the Barco neckboard. I in fact have here a Barco 909 switcher, driver and neckboard to play with, but no machine to put in. The point is I have to find time for measure what the Barco output hybrid's bandwidth really is.
Regardless for better understanding I need informations that the circuit descriptions and diagrams don't tell.
Could you guys give me a general overview on the Barco 909 menu system regarding the color settings? With NEC and Electrohome I know, there is a general contrast and brightness menu, and an other for white balance, that consisted of G2 (~individual brightness) and drive (~individual contrast). Is the Barco the same? Also, as I understand with Barco the ABL (Automatic Black Level) circuitry is always working (in a NEC this can be disabled, an Electrohome don't have such feature at all), does this affect the practical usage of the projector in any way, does this leave all of the above settings accessible to the user still? For this mod it would be much easier to keep the ABL out of the equation, as it is rather difficult to copy its mechanism and also plays a big role in why the Barco signal chain is that complicated.
@ gregstv After having a night of sleep over it I will leave it to you gregstv , you are much further in the proces then I am ,time is a problem for me ,for the moment trying to fix a quad went through all my spare quads in no time.
@ giaky Replacing the hole vnb is a rather drastic move but it would combine the best of both worlds. I realy would like to know what the bandwith of the barco output hybrid is but haven't figured out how to do a reliable measurement without influencing the circuit.
@ gregstv After having a night of sleep over it I will leave it to you gregstv , you are much further in the proces then I am ,time is a problem for me ,for the moment trying to fix a quad went through all my spare quads in no time. Did you bake the quad before using them?
zjjxhzf: hello Gabor i am DLP projectorColor wheel is not accurate，setup memory， the phase angle cant setting for the color wheel ，must use service code.
Sept 19, 2017 1:31:25 GMT -5
mastertech: Hi stranger. Guess you spent your summer cruising on that street bike.
Sept 17, 2017 21:43:54 GMT -5
nashou: Hey everyone, just saying hi ! Hvent been here for a while hope you're all doing well !!
Sept 17, 2017 19:19:25 GMT -5
mastertech: Parts for repair are no longer available.
Sept 11, 2017 19:42:24 GMT -5
mayavi: my pioneer elite VSX-92TXH it freezes until I unplug and then it won't power on until maybe 10 minutes. came to know that its a common problem in this model. any help would be much appreciated......
Sept 11, 2017 13:39:10 GMT -5
jaredjaric: Thanks so much Hulio :), your expertise is very much respected
Aug 20, 2017 9:25:37 GMT -5
Admin: james: you need to post in the thread where your problem is being discussed.
Aug 9, 2017 19:51:54 GMT -5
james: Yes Sir All wiring was connected.
Aug 9, 2017 7:46:15 GMT -5
Admin: I have uploaded a copy of the SM to the digital projector section.
Jan 10, 2017 20:21:56 GMT -5
ducki: sorrry for my bad english ....(google translate
Jan 10, 2017 17:44:21 GMT -5
ducki: I have the same defect as a cp-x4021n you but can not start it ... I did the same trials with ic202 pc102 and still do not like, I make short pin 1 and 2 of the pc102 and PJ light (orange) goes off ... you can help me with a service manual for this PJ? TNX
Jan 10, 2017 17:43:46 GMT -5
jlb12: pwr switch off = 2(0.0) 3(11.7) 6(.04) 7(.04)
Dec 13, 2016 23:27:03 GMT -5
jlb12: No Problem. Thank you for all your help.
Dec 13, 2016 0:20:40 GMT -5