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Discussion Starter · #1 ·
Hmmm,


Just got a Sept. 1999 BG1208s/2 with 1100 hours in the door... (a tough task - WOW this beast is heavy). I have so far been kind of happy with my BG801s and my BD701s. BUT the step up has been there a while!!!

Well here are my questions

When i install the PJ on the floor approx at the same distance as my BG801s, connect my HTPC and send a 1280x720 (or any other resolution) through, I cannot get an image that will fill the raster area (- 1/4 inch on each side). With H size/amplitude set at 99, the image is still FAR from the phosphor edges on the tube face?


Can someone explain how I might increase the horizontal amplitude on the BG1208s/2. I have not a Service Manual at hand. I have seen pages from the BG808s, but the boards and the placement are not exactly the same?

Question nr. TWO

Is it straight forward to adjust the G2 on this? It does have a G2 setting in the service menue... The problem is - when no source, or a source is present, the blue tube show the raster all the time with LOTS of noise and waves, all over... Can I without destroying anything, turn the adjustments on the G2 board till the LEDs on the RGB output boards is turned off? Or do I need a scope to monitor different voltages?


Thanks...
 

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As soon as Gn2 checks in, we will all be informed properly.:)
 

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Q#1 - Your 'maximum horizontal width voltage' is probably set a little low such as to the factory setting of 48 Vdc - I seem to have width issues if its set to 48.0 Vdc myself. You need a voltmeter and a service manual that shows where to connect it and which POT to turn. I'll look around and see what I might have, but the basic procedure is input a standard NTSC/PAL video signal, set brightness and contrast to 50, set horizontal width to 99, and then set the voltage to 48 Vdc. You measure the voltage in a risky location on the horizontal deflection board and the POT is on the daughterboard on the SMPS.


I say risky because there really isn't a place to clip the voltmeter lead so you have to manually hold it on a transistor tab that's very close to a grounded clip that you could accidentally short out the circuit to.


I don't know what other people think is an acceptable high-end value to set this voltage to, but I've seen it way over 50 Vdc on some units which seems way too high and dangerous - I wouldn't do that. I'd also resist the temptation to just turn the POT without measuring the voltage...


Just remember, you must measure the voltage with a standard video signal (eg, 15kHz/50Hz).


Q#2 - As you mentioned, G2 is set for that model using the service menu option adjustment. Its pretty easy to do since that's the case. Normally you just go to that menu item and then adjust the G2 POTs to extinguish the LED on each output amp board and you're done. If everything is okay a scope is not required.


Based on what you've described I would say there is a chance that your output amp on that blue tube could be bad - maybe the ABL circuit. Try the G2 adjustment but if that doesn't work the next typical step would be to swap the output amp with another tube and see if the problem moves with the amp.


Mark
 

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Discussion Starter · #4 ·
Thanks,


I could not wait for an answer, and downloaded the BG1209s Service Manual yesterday ($10 from crtcinema). This is probably the "closest" manual, since the tubes and optics are the only difference. I could not find any manuals newer than the 1208/2...?


Q1 - I read through the Service Manual and observed what you state. Did not have a Voltmeter at hand and made a "tiny" adjustment that did the trick. Shall "do the right thing" maybe today or tomorrow.


Q2 - Yes, my findings are more close to your inputs... G2 seems fine. The noise is all over the surface area that are covered by the raster. But since I can make it disappear by turning down the blue pot on the G2 board, I think the tube is not GONE...? I will try and swap the neck board from one of the other two and fire it up.


Anyhow, with the troubles put aside, I'm impressed with what I saw with respect to sharpness compared to my BG801s. The colors are probably better on the 801s


Thanks again,
 

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Discussion Starter · #5 ·
Here is a "blur" picture of what is shown on the phosphor with black input (aka Zoomplayer in Stop).

http://home.online.no/~al-t/Blue.JPG


The other two tubes do not have similar pattern. The Blue does respond to G2 adjustment. If I turn down the G2, then the pattern disapears, but so does the picture...


I will try later tomorrow to swap neckboard. But only after having discussed with the once who presumably did a service on this unit before I got it? Maybe they can tell me something?


The Red and the Blue tube have no wear on the phosphor at all, the green show start of something, but still very weak.
 

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Discussion Starter · #6 ·
Hmmm


I have moved neckboard from green to blue - RESULT the blue still have noise, shows much of the raster and with angeled highlighted lines (6 or seven) on the raster (looks like retrace line only more of them...)


I have moved the J1 connector on the neck board (RGB input +++) from the green to the blue, same result the noise stays with the blue tube.


I have removed the Convergence board - RESULT still the same noise on the tube surface...


Could I try exchanging the J2 connector (G1 and G2 voltage feed) for blue and green, and see if the noise is fed through the G2 circuit? Or is that dangerous?


Another one is moving the high voltage feed from green to blue and so forth? that shouldn't be any worry?


Otherwise I am in the blind here?

Pleas help me...!!!


Thanks
 
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