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Agfa
Joined: 02 Nov 2022
Posts: 2
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| Posted: Tue Apr 23, 2024 4:22 pm Post subject: new g70 owner questions |
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Hi all, or those of you still here in 2024. I've been reading the forum for a while, it's a wealth of knowledge. I'm trying to iron out some final kinks with my G70 setup.
I got the projector a couple years ago now, but just got around to deploying it recently. Currently running a 72" 4:3 screen and watching both 4:3 and widescreen content. Getting a ton of enjoyment out of it overall through watching, and tweaking. Aligning different resolutions is actually kind of fun, though I did discover this hobby via the direct-view CRT enthusiast community.  I'm very happy with the image I've been able to get but there are a couple aspects where I'm seeking advice:
1. gamma and white balance
for some reason it's calibrating to an extremely low gamma, around 1.8-1.9, and my red and blue biases are all messed up. I'm able to mostly correct this with a software 3DLUT on my PC which is the main source I'm using, but I'm wondering if this is a hardware issue. The DAC I'm using is John Wyman's IFB DVI v2 card. Screenshot of my readings in HCFR:
2. focus
this may just be poor adjustment of MG focus and lens focus on my end, but it seems like it's not as sharp as it can be. I'm curious about the CRT rings and whether it's recommended to adjust them. It looks like they're still fixed with the goop from the factory. I've tuned convergence rings on color tubes, how does this compare in difficulty?
3. front IR receiver busted
not sure if it's just dead, but if I switch it to just front in the menu it's non responsive. Not a huge issue since I can used the remote wired or just aim at the screen and the reflected light hits the rear mounted receiver fairly reliably. I looked at the board and I'm not sure how to go about replacing just the receiver itself, looks like the whole piece needs to be swapped.
Thanks for any tips! Here's some bonus pics (from a few weeks ago before I improved convergence more)
https://i.imgur.com/ck1odgC.jpeg
https://i.imgur.com/6kckiwR.jpeg
https://i.imgur.com/hcyTVnv.jpeg
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AFryia
Joined: 09 Mar 2006
Posts: 965
Location: S.E. Michigan VPH-G70Q
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| Posted: Sat Apr 27, 2024 5:20 pm Post subject: Re: new g70 owner questions |
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| Agfa wrote: |
1. gamma and white balance
for some reason it's calibrating to an extremely low gamma, around 1.8-1.9, and my red and blue biases are all messed up. I'm able to mostly correct this with a software 3DLUT on my PC which is the main source I'm using, but I'm wondering if this is a hardware issue. The DAC I'm using is John Wyman's IFB DVI v2 card. Screenshot of my readings in HCFR:
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This sounds like my setup I used to run G-70 & John's IFB. I too tried modifying the LUT through the HTPC. I abandoned it because too much correction was messing with the color fidelity.
My best results <3 delta E was after taming the blue hump, lowering the RGB gains. Then grey scale tracking was very good, Gamma was any where from 1.8 to 2.4, fade to black was very good also. You will loose light output, so you want to be in a light controlled room for best results.
| Agfa wrote: |
2. focus
this may just be poor adjustment of MG focus and lens focus on my end, but it seems like it's not as sharp as it can be. I'm curious about the CRT rings and whether it's recommended to adjust them. It looks like they're still fixed with the goop from the factory. I've tuned convergence rings on color tubes, how does this compare in difficulty?
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The goop, I assume you are talking about the CPC tabs/magnets at the back of the CRT tube. This could help with beam astigmatism, I would leave this alone until you are sure everything else is set right. You are dealing with high voltage in that area.
Those are not convergence rings, those are for lens flapping, aka Scheimpflug, and optical focus. You need that set so the whole image is in focus. not just the center. Mind you the corners will never look as sharp as the center. IMO you need to set lens flapping and optical focus using Guy Kou's the phosphor grain technique.
| Agfa wrote: |
3. front IR receiver busted
not sure if it's just dead, but if I switch it to just front in the menu it's non responsive. Not a huge issue since I can used the remote wired or just aim at the screen and the reflected light hits the rear mounted receiver fairly reliably. I looked at the board and I'm not sure how to go about replacing just the receiver itself, looks like the whole piece needs to be swapped.
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I just got an inexpensive Nile repeater and plugged into the back I/R port, or maybe I used one of those emitters with the sticky tab.
| Agfa wrote: | Thanks for any tips! Here's some bonus pics (from a few weeks ago before I improved convergence more)
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Lens flapping, optical focus, mechanical toe. Go through the steps a couple if iterations because adjusting each one has an effect on the other. Get this right before any electronic convergence or adjustment.
this assume your rasters are reasonably centered and don't need adjustment.
Good Luck!
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