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Post by Casethecorvetteman on Dec 23, 2017 6:22:36 GMT -5
It would be pretty straightforward to do that tube swap. The key is to collect the right yokes together those match to the XG electronics and can fit on a 9" tube. The deflection yoke is the most important to get matched, that should be a Sony G90 yoke or maybe a 1292. The rest is machine work and find out the proper wiring of the coils. Wont need much machine work, ill whack it all into a Barco 909 chassis and fit all the boards into that. The mounting of 9" LC housings into an XG would never be easy, but fitting XG boards into that massive Barco chassis wouldnt be too much trouble. There would be a bit of jiggery pokery, but i reckon fitting all that into a larger chassis is doable. The top two boards would be the hardest part, but not impossible. The power supply can go on the underside of the chassis when it goes on the ceiling if need be. |
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Post by Casethecorvetteman on Dec 23, 2017 6:25:57 GMT -5
If i had a G90 or 1292 i wouldnt bother, but i want that high brightness for video game light guns, and the 8" set is driven really hard to push past an 85" screen bright enough for the guns to see well, and the gun games dont work on the Cine 9 because of the 32kHz minimum scan rate.
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Post by gjaky on Dec 23, 2017 6:48:24 GMT -5
If i had a G90 or 1292 i wouldnt bother, but i want that high brightness for video game light guns, and the 8" set is driven really hard to push past an 85" screen bright enough for the guns to see well, and the gun games dont work on the Cine 9 because of the 32kHz minimum scan rate. Understand, then convince Greg to sell his 1292 to you  Or better yet get some Barco 1209 (those are really cheap these days) and you are good to go. I don't mention the Marquees because I've heard they are quite rare down under, otherwise those have the best bang for the buck factor. |
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Post by gjaky on Dec 23, 2017 15:34:40 GMT -5
BTW how many different light gun system do you have? Perhaps it is not too difficult to modify the gun, to make it more sensitive?
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Post by Casethecorvetteman on Dec 24, 2017 20:28:23 GMT -5
If i had a G90 or 1292 i wouldnt bother, but i want that high brightness for video game light guns, and the 8" set is driven really hard to push past an 85" screen bright enough for the guns to see well, and the gun games dont work on the Cine 9 because of the 32kHz minimum scan rate. Understand, then convince Greg to sell his 1292 to you Or better yet get some Barco 1209 (those are really cheap these days) and you are good to go. I don't mention the Marquees because I've heard they are quite rare down under, otherwise those have the best bang for the buck factor. Yeah mate, theyre all rare down here. NECs and smaller Sonys are the more common, even Vidikrons come up as often as 9" Barcos |
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Post by Casethecorvetteman on Dec 24, 2017 20:36:40 GMT -5
BTW how many different light gun system do you have? Perhaps it is not too difficult to modify the gun, to make it more sensitive? Most of them, except SNES, ive pretty near got every gun for every other console up to Dreamcast and PS2. I think the Dreamcast and PS2 guns WILL work with certain games that are 640x480p, but not all of them do run at that. There are certain guns that work fine on the XG, like the Namco Guncons and the Predator 2 ( as well as variants, but only the Guncon compatable versions ) |
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Post by gjaky on Apr 19, 2018 16:09:49 GMT -5
Some crappy screenshots this time... All of them are blurry due to camera settings, and also because the projector was not set up properly. the source was HTPC (HDMI) and a slightly modified version of the $20 white chinese HDMI converter (that only supposed to accept up to 1080P 60Hz signals, ahem...). Ultimate VNB-DB: It is built upon a ~'97 Rev. 5 "classic" VNB, Only FB3 was removed, and the entire input section was bypassed, so the ULTIMATE VNB-DB board directly drives Q19. Although there is no intentional peaking in the setup, the system peaks around the 1080P 72Hz clock rate, bandwidth both at lower and higher clock rates look less. 1080P 72Hz:  Regular VNB-DB: It is built upon a similar ~'97 built Rev.5 classic VNB, it has some performance modifications too: changed R22 to 130Ohm, added extra (2u2) ceramic capacitors to the CLC449's rails, removed R90, FB3 and C53. The board seems to loose some bandwidth from very low clock rates, ie. 1080P 60Hz is not fully resolved (but 1080i 60Hz does), the effect is not dramatic however, what is more interesting this does not worsen, not even a tiny bit, even at 1080P 95Hz (mind the chinese HDMI converter too) 1080P 60Hz:   1080P 72Hz:   1080P 85Hz:   1080P 95Hz:   |
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Post by stridsvognen on Nov 7, 2018 12:20:33 GMT -5
AD835 DB board moome card 1080P 72fps 195Mhz Behaves extremely linear from black to full white, and only a very light roleoff. Ill concider this a new bandwidth reference. There is 0 visible difference between 1080P 60fps 148Mhz and 195Mhz on the SMPTE test.   |
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Post by gjaky on Aug 1, 2019 3:26:32 GMT -5
Not that modifying CRT projectors are still a hot topic, but I have to entertain myself with something... Here is a new development waiting for trial. This is a modification board specifically for Marquee projectors. This daughter board follows the conventional circuit topology like the original VIM: signal switch followed by a variable gain amplifier. But with all new components, this is not based on the AD834/835 multipliers anymore, instead a variable gain amplifier called VCA824. Regarding bandwidth the previous VNB-DB boards were already as good as needed, but it is somewhat difficult to deal with as it needs the VIM, VNB, LVPS and HDM modified to various extent. While the later two is a recommended modification to any Marquee anyway, it is still somewhat demanding to carry out such modification. This new board is aimed to overcome this weakness, it again contains all signal processing on a single PCB, but this time located on the VIM, with retaining the miniRCA connectors it would be possible to upgrade the signal path is a simple way. The board is so much self contained that only minimal modification would be needed to the VIM: adding only three resistors and tapping certain control signals, and of course the video input. The VCA824 multiplier has 700MHz bandwidth (even better than the AD834, while cheaper than that!) and offers easily adjustable gain (beyond unity), which was torublesome on the AD834 and non exsitent with the AD835. Also very low noise. The signal switch is called TMUX154E, which also appears to be an excellent switch with good isolation (which is further augmented by double switching scheme), 900MHz bandwidth, while having low on channel resistance and low input capacitance.
Overall I'd expect similar bandwidth performance as possible with AD834 at a lower cost and labour.
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Post by stridsvognen on Aug 1, 2019 6:23:55 GMT -5
Nice work there, and super exiting to see how it will work.
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Post by gjaky on Aug 2, 2019 14:23:52 GMT -5
And the actual PCB...  |
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Post by gjaky on Sept 25, 2019 5:37:54 GMT -5
Yesterday the first prototype of the VIM-DB came alive on the bench. It works good and the bandwidth is apparently very high, I barely could detect any signal degradation to the test signal on my oscilloscope, and my scope is 250+ MHz, compared to the VNB's 100-120MHz.
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nidi
Junior Member
Posts: 72
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Post by nidi on Sept 30, 2019 11:41:49 GMT -5
Gabor, any exciting news on the VIM-DB??
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Post by gjaky on Oct 1, 2019 0:56:35 GMT -5
Gabor, any exciting news on the VIM-DB?? I guess the meaning of the term "exciting" varies wildly... 
Anyway, over the weekend I made a hybrid test rig with red channel taken over by VIM-DB and geen channel was left original, this way I was able to compare the mod channel to the stock VIM - VNB channel, and it looked like they are functionally interchangeabl, meaning it is doing what it should do. Here is a picture of the fully assembled board. I should put this on a VIM and send it to Denmark for critical performance testing.
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nidi
Junior Member
Posts: 72
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Post by nidi on Oct 14, 2019 10:27:27 GMT -5
any news on your latest work?
Gabor, has your latest work gone north-west by post yet?
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Or better yet get some Barco 1209 (those are really cheap these days) and you are good to go. I don't mention the Marquees because I've heard they are quite rare down under, otherwise those have the best bang for the buck factor.
