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Discussion Starter · #1 ·
I can`t get the vertical size small enough to fit my 16:9 screen. Is there a pot somewhere that will reduce the vertical size? Vertical size in the menu is currently at zero, and the picture is still slighly larger than the screen. Resolution on the HTPC is 1280x720, 75Hz.
 

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Gunnar, try a search. I remember seeing a picture posted with the pot. Fortunately, my 808s is just right at zero.

Bill
 

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There are POTs for red and blue vertical amplitude on the vert/sync board, but there isn't one for green that I'm aware of. If you have the 'green only' convergence optional board you might be able to squeeze the green down a bit more using those controls.


Mark
 

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I had the same problem with my 808s but I was able to (almost) cure the problem by reducing the projection angle by a few degrees. But my settings are still close to zero. Actually, I think the number is lower for 720p than for 1080i or 480p. It must be a function of line frequency.


Graham
 

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Discussion Starter · #5 ·
OK, I`ll probably have to overscan a bit and use blanking. Maybe there is a resistor or something that can be changed as on some of the EH-models?


Gunnar
 

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There is an easy fix!


The BG808s has an optional "convergence on green" module that causes this problem, check your convergencemenu for this option. This board can be removed without problem, and whoops, you get enough adjustment too obtain correct anamorphic squeeze.


This is also covered by Henry at crtprojectors.co.uk in his excellent FAQ.

http://www.crtprojectors.co.uk/crt_faq.htm


Scroll down until you see the link called:


Will all Barco digital chassis projectors do both 4:3 and 16:9 geometry?


Click and read :)


Frode
 

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Discussion Starter · #8 ·
Frode,

Unfortunately there isn`t any "convergence on green" menu item on my BG-808s.


Gunnar
 

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I took a brief look myself a couple of days ago. I think what I remember considering was pulling a 10k resistor in the green circuit coming from V-AMP and inserting a resistor and POT in its place just like those in the parallel red/blue circuits - looked too easy so I might have misinterpreted it. It sort of begs the question if the vertical size of red and blue can be shrunk enough to fit in the first place though.


Mark
 

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Mark,


rather than putting a pot in the Green circuit, then backing off on all 3 to fit, it's better to insert a pot in the main V-AMP supply chain that drives all 3, then just continue to use the R and B as offsets to balance the G.


I could tell you the precise spot to do this on a BG800, if I checked my service manual, but you'd have to locate the corresponding location for the 808s.


Replacing a single resistor is also a viable option, if you're short on time or cash, but I prefer the flexibility a trim-pot provides.


- Tim
 

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Hello


Ok I spent some time on it.

On the sub unit of the vertical deflection board is a digital potmeter that adjust the vertical size (IC2).

The Dig pot is feed with an couple of resistors coming from a 3V power supply resistors are R365 1k82-R366 1k-367 150 an a signal from an op-amp.

Try to adjust the 1k r366 a bit to 1k2 or 820.

I didn't try it so do it at your own risk.


Rob
 
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