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THE MOD
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racerxnet



Joined: 20 Jun 2007
Posts: 362
Location: Illinois


PostLink    Posted: Wed Aug 30, 2017 1:40 pm    Post subject: Reply with quote


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I have a ground wire (White-top left hand side) in the pic which the old boards did not have and I do not see a tab for the quick connect. Any ideas where to secure?



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gjaky



Joined: 05 Jun 2010
Posts: 2655
Location: Budapest, Hungary


PostLink    Posted: Wed Aug 30, 2017 3:10 pm    Post subject: Reply with quote

Every neckboard came with those two grounding cables from factory. The one you ask should tied near the VNB power connector, there are two tabs on the lower part of the cage, one is even visible on your picture, between the red video cable and the corner of the VNB power connector...
Also make sure to connect the G2 lead to pin2.

_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB
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racerxnet



Joined: 20 Jun 2007
Posts: 362
Location: Illinois


PostLink    Posted: Wed Aug 30, 2017 6:19 pm    Post subject: Reply with quote

Thanks.

Just making sure to install as Ehome did.

MAK
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jbmeyer13



Joined: 03 Dec 2010
Posts: 1131



PostLink    Posted: Fri Sep 08, 2017 1:45 pm    Post subject: Reply with quote

When are we going to see some screen shots? I've been patient enough..lol
_________________
Projector: Modded 9501LC ULtra- MP VIM, Vold VNB, ETECH LVPS, Silver VIM Cables, HD10F's & a V1 case!
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racerxnet



Joined: 20 Jun 2007
Posts: 362
Location: Illinois


PostLink    Posted: Fri Sep 08, 2017 3:27 pm    Post subject: Reply with quote

jbmeyer13 wrote:
When are we going to see some screen shots? I've been patient enough..lol


Just got back from vacation. I'll be finishing it up after my work week. I've had several PM's from others that are looking forward to some information. Also others who have said the mod's are very good. How about you, any shots from your set up?

MAK
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jbmeyer13



Joined: 03 Dec 2010
Posts: 1131



PostLink    Posted: Fri Sep 08, 2017 6:14 pm    Post subject: Reply with quote

Only thing I shoot screen shots of is test patterns because it's not dependent on a proper calibration. IMO, that is the only useful way to evaluate BW performance for a video chain. All other attributes have to be seen in person to understand the results. Getting a camera to come remotely close to displaying what is onscreen is not something I have interest in and is a hobby all to itself.

_________________
Projector: Modded 9501LC ULtra- MP VIM, Vold VNB, ETECH LVPS, Silver VIM Cables, HD10F's & a V1 case!
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gjaky



Joined: 05 Jun 2010
Posts: 2655
Location: Budapest, Hungary


PostLink    Posted: Fri Sep 08, 2017 7:56 pm    Post subject: Reply with quote

jbmeyer13 wrote:
Only thing I shoot screen shots of is test patterns because it's not dependent on a proper calibration. IMO, that is the only useful way to evaluate BW performance for a video chain.


I can agree, providing the input parameters are known for the specific test pattern screenshot, ie. what pixel clock was it when the picture was taken.

_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB
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jbmeyer13



Joined: 03 Dec 2010
Posts: 1131



PostLink    Posted: Sat Sep 09, 2017 8:17 pm    Post subject: Reply with quote

gjaky wrote:
jbmeyer13 wrote:
Only thing I shoot screen shots of is test patterns because it's not dependent on a proper calibration. IMO, that is the only useful way to evaluate BW performance for a video chain.


I can agree, providing the input parameters are known for the specific test pattern screenshot, ie. what pixel clock was it when the picture was taken.

That shot was 1080p/72 and the pixel clock was 195mhz. The clock runs that high to shift the ringing out of the image via porch adjustment.

_________________
Projector: Modded 9501LC ULtra- MP VIM, Vold VNB, ETECH LVPS, Silver VIM Cables, HD10F's & a V1 case!
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gjaky



Joined: 05 Jun 2010
Posts: 2655
Location: Budapest, Hungary


PostLink    Posted: Sun Sep 10, 2017 10:02 am    Post subject: Reply with quote

jbmeyer13 wrote:

That shot was 1080p/72 and the pixel clock was 195mhz. The clock runs that high to shift the ringing out of the image via porch adjustment.


For that it is suprisingly good, actually it looks perfectly resolved.
Knowing the phisical constraits of the VNB it is impossible to reach such bandwidth without extra peaking (or preemphasis if you like that phrase better) involved in the preamplifier stage.
I am not a fan of that kind of peaking thing, it may look good at test pattern but it also introduce distortion and noise to the signal. My boards will never look that well resolved, I try to aim for frequency flatness wich is IMO the purest presentation of the video signal.
The AD835 VNB-DB has a -1dB roll off at 1080P 72Hz (~200MHz pixel clock) and a selected modified VNB will add another -2dB roll off that is -3dB overall roll off. With the ULTIMATE VNB-DB (AD834) it is possible to resolve 1080P 72Hz at preamplification level with no loss (-0dB), but still there is the loss at the VNB.

_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB
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mp20748



Joined: 12 Sep 2006
Posts: 5359
Location: Maryland

TV/Projector: 9500LC Ultra / Super 02 and 03 VIM


PostLink    Posted: Sun Sep 10, 2017 11:34 am    Post subject: Reply with quote

gjaky wrote:
jbmeyer13 wrote:

That shot was 1080p/72 and the pixel clock was 195mhz. The clock runs that high to shift the ringing out of the image via porch adjustment.


For that it is suprisingly good, actually it looks perfectly resolved.
Knowing the phisical constraits of the VNB it is impossible to reach such bandwidth without extra peaking (or preemphasis if you like that phrase better) involved in the preamplifier stage.
I am not a fan of that kind of peaking thing, it may look good at test pattern but it also introduce distortion and noise to the signal. My boards will never look that well resolved, I try to aim for frequency flatness wich is IMO the purest presentation of the video signal.
The AD835 VNB-DB has a -1dB roll off at 1080P 72Hz (~200MHz pixel clock) and a selected modified VNB will add another -2dB roll off that is -3dB overall roll off. With the ULTIMATE VNB-DB (AD834) it is possible to resolve 1080P 72Hz at preamplification level with no loss (-0dB), but still there is the loss at the VNB.



I agree here, and have been using peaking on most of my boards. But the slightest form, because I enhance the performance of the AD835 overall in other areas. And the other thing that makes the peaking slightly needed is the modified neck boards I use with the VIM. So with the slight peaking, I was not able to notice any distortion, using any of my test patterns for it, nothing by scope either. And you are right, the flat is the best way to go, because you'll be maintaining natural signal integrity for the best overall HD. And you can go along ways using the AD835, but you have to clean-up all connections to it.



Quote:
but still there is the loss at the VNB


I'm glad someone else agrees with me on this, because I'm burning out trying to convince someone else those boards are limited, as you also pointed out. And that is what I've been saying when I said they were not designed to do 1080P 72hz fully resolved, so there will be roll-off.

The AD834 is a better chip for first stage or pre-amplifier as you put it, and has an amazing flat response. But is a noisier chip to work with. It's higher bandwidth windows also allows hash or trash noise to be a problem, that usually shows on the screen as being a dust or cloud in the image. The stock neck boards will respond better to a flatter bandwidth than -3db though.

I really like reading your commentary and data on this stuff as I've told you before. Nothing you post is wishful thinking and that says a lot about you.

_________________
We're no longer offering Mods. There are other options available from other sources these days. We are still supporting any previous work.
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gjaky



Joined: 05 Jun 2010
Posts: 2655
Location: Budapest, Hungary


PostLink    Posted: Sun Sep 10, 2017 9:00 pm    Post subject: Reply with quote

There could be more drastical modifications made to the VNB those may enable some more bandwidth. One is to substitute the 400 Ohm Caddock power resistors with a similar but 330 Ohm type, this could speed up the turn off time of the VNB by ~17%, but on the other hand the heat dissipation of the transistors would increase by this 17% as well (while maintaining the same output level), and the transistors would operate at their maximal allowable dissipation level, which may be a concern...
An other possibility would be to use a so-called charge pump circuitry but this would mean several high speed transistors added to the PCB of the VNB which may be difficult to achieve beacuse of the strict layout of the VNB.

_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB
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mp20748



Joined: 12 Sep 2006
Posts: 5359
Location: Maryland

TV/Projector: 9500LC Ultra / Super 02 and 03 VIM


PostLink    Posted: Mon Sep 11, 2017 11:21 am    Post subject: Reply with quote

gjaky wrote:
There could be more drastical modifications made to the VNB those may enable some more bandwidth. One is to substitute the 400 Ohm Caddock power resistors with a similar but 330 Ohm type, this could speed up the turn off time of the VNB by ~17%, but on the other hand the heat dissipation of the transistors would increase by this 17% as well (while maintaining the same output level), and the transistors would operate at their maximal allowable dissipation level, which may be a concern...
An other possibility would be to use a so-called charge pump circuitry but this would mean several high speed transistors added to the PCB of the VNB which may be difficult to achieve beacuse of the strict layout of the VNB.


Yes, but achieving higher bandwidth has already been done here. And even without changing those resistors, on a board set that can do 300mhz+, the six transistors still run very hot. So hot that I had put tape over the openings on the tube covers, as to get the most air to the neck boards. I also remove and leave off the neck board covers for best ventilation.

I don't run the boards that high anymore, but still cover the holes on the tube covers, because at the 200mhz window that I'm now using, they still run hotter. I run them at 200mhz for best noise floor. Going above that increases the image hash noise, and would not be necessary at all.

You should visit the states and spend a day here. I've been working on my shop and would love to share some of what I've been doing and let you see how I look at things in the video chain.

The stock boards have several problems. The NPN pre-driver is one of the worse. It is a 2GHZ Wide Band transistor, that should have been higher in that stage... but the real problem with it was my discovery. It fails from heat and drive. And it would be the main reason the boards loose bandwidth. Using it there is also why they had to peak (C54 - R4) the input of it. And you know the last place to use peaking would be on the neck boards.



.

_________________
We're no longer offering Mods. There are other options available from other sources these days. We are still supporting any previous work.
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gjaky



Joined: 05 Jun 2010
Posts: 2655
Location: Budapest, Hungary


PostLink    Posted: Mon Sep 11, 2017 1:59 pm    Post subject: Reply with quote

Yes, I also played with that predrive transistor but my results are mixed. I use the 2SC3613 as an upgrade, but the improvement in rise time was up to 200ps but once I got even worse result that with the original transistor. But I also noticed that once I removed and put back the MRF transistor it remained functional, but eventually lost its speed, so it is a sensitive part indeed.
As for the speed while the switch on time of the CRT amplifier is affected by the transistor's speed, the turn off time is dominated by the parasitic collector capacitance of the upper transistor (the common base) which is around 5-6pF (which is not much at all!) and the power resistor, here 400 ohm. The time constant is around 5ns therefore. This can be tuned slightly by the inductor peaking, and is around 4ns in reality, but again this is a barrier that is independent from the speed of the used transistors. For proper (non peaked) 1080P 72 Hz we would need 2.5 ns switch on/off times on the neckboard.

_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB
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jbmeyer13



Joined: 03 Dec 2010
Posts: 1131



PostLink    Posted: Wed Sep 20, 2017 2:08 pm    Post subject: Reply with quote

racerxnet wrote:
jbmeyer13 wrote:
When are we going to see some screen shots? I've been patient enough..lol


Just got back from vacation. I'll be finishing it up after my work week. I've had several PM's from others that are looking forward to some information. Also others who have said the mod's are very good. How about you, any shots from your set up?

MAK


Hey MAK-

You've gone dark on us; any updates?

_________________
Projector: Modded 9501LC ULtra- MP VIM, Vold VNB, ETECH LVPS, Silver VIM Cables, HD10F's & a V1 case!
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CIR Engineering



Joined: 25 Aug 2008
Posts: 3887
Location: Chicago USA & Berlin Germany

TV/Projector: Sony G90 – RadiancePro 4446 - Moome FullHDv2 3D


PostLink    Posted: Wed Sep 20, 2017 11:20 pm    Post subject: Reply with quote

jbmeyer13 wrote:
Only thing I shoot screen shots of is test patterns because it's not dependent on a proper calibration. IMO, that is the only useful way to evaluate BW performance for a video chain. All other attributes have to be seen in person to understand the results. Getting a camera to come remotely close to displaying what is onscreen is not something I have interest in and is a hobby all to itself.

THANK YOU. I have said that so many times...

Thumbs Up
craigr

_________________
JETI Specbos 1211 Spectroradiometer
Photo Research PR-650 Spectroradiometer
Klein K10-A Laboratory Grade Colorimeter
Murideo Fresco SIX-G HDMI 2.x Multimedia Generator
Murideo Fresco SIX-A HDMI 2.x Analyzer
*NEW Light Illusion LightSpace XPT Pro Version 10.x Color Calibration Software
ChromaPure3 Pro Color Calibration Software
Sencore CR7000 CRT Tube Analyzer / Rejuvenater
Audyssey MultEQ Pro Audio Calibration System
Authorized Dealer for Lumagen & just about everything else Wink
www.CIR-Engineering.com - craigr@cir-engineering.com
Phone: 865-405-6892
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CIR Engineering



Joined: 25 Aug 2008
Posts: 3887
Location: Chicago USA & Berlin Germany

TV/Projector: Sony G90 – RadiancePro 4446 - Moome FullHDv2 3D


PostLink    Posted: Wed Sep 20, 2017 11:23 pm    Post subject: Reply with quote

gjaky wrote:
For that it is suprisingly good, actually it looks perfectly resolved.
Knowing the phisical constraits of the VNB it is impossible to reach such bandwidth without extra peaking (or preemphasis if you like that phrase better) involved in the preamplifier stage.
I am not a fan of that kind of peaking thing, it may look good at test pattern but it also introduce distortion and noise to the signal. My boards will never look that well resolved, I try to aim for frequency flatness wich is IMO the purest presentation of the video signal.

Thank you too. I have also been saying the same thing for almost 20 years!

craigr

_________________
JETI Specbos 1211 Spectroradiometer
Photo Research PR-650 Spectroradiometer
Klein K10-A Laboratory Grade Colorimeter
Murideo Fresco SIX-G HDMI 2.x Multimedia Generator
Murideo Fresco SIX-A HDMI 2.x Analyzer
*NEW Light Illusion LightSpace XPT Pro Version 10.x Color Calibration Software
ChromaPure3 Pro Color Calibration Software
Sencore CR7000 CRT Tube Analyzer / Rejuvenater
Audyssey MultEQ Pro Audio Calibration System
Authorized Dealer for Lumagen & just about everything else Wink
www.CIR-Engineering.com - craigr@cir-engineering.com
Phone: 865-405-6892
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CIR Engineering



Joined: 25 Aug 2008
Posts: 3887
Location: Chicago USA & Berlin Germany

TV/Projector: Sony G90 – RadiancePro 4446 - Moome FullHDv2 3D


PostLink    Posted: Wed Sep 20, 2017 11:27 pm    Post subject: Reply with quote

mp20748 wrote:
gjaky wrote:
jbmeyer13 wrote:

That shot was 1080p/72 and the pixel clock was 195mhz. The clock runs that high to shift the ringing out of the image via porch adjustment.


For that it is suprisingly good, actually it looks perfectly resolved.
Knowing the phisical constraits of the VNB it is impossible to reach such bandwidth without extra peaking (or preemphasis if you like that phrase better) involved in the preamplifier stage.
I am not a fan of that kind of peaking thing, it may look good at test pattern but it also introduce distortion and noise to the signal. My boards will never look that well resolved, I try to aim for frequency flatness wich is IMO the purest presentation of the video signal.
The AD835 VNB-DB has a -1dB roll off at 1080P 72Hz (~200MHz pixel clock) and a selected modified VNB will add another -2dB roll off that is -3dB overall roll off. With the ULTIMATE VNB-DB (AD834) it is possible to resolve 1080P 72Hz at preamplification level with no loss (-0dB), but still there is the loss at the VNB.



I agree here, and have been using peaking on most of my boards. But the slightest form, because I enhance the performance of the AD835 overall in other areas. And the other thing that makes the peaking slightly needed is the modified neck boards I use with the VIM. So with the slight peaking, I was not able to notice any distortion, using any of my test patterns for it, nothing by scope either. And you are right, the flat is the best way to go, because you'll be maintaining natural signal integrity for the best overall HD. And you can go along ways using the AD835, but you have to clean-up all connections to it.



Quote:
but still there is the loss at the VNB


I'm glad someone else agrees with me on this, because I'm burning out trying to convince someone else those boards are limited, as you also pointed out. And that is what I've been saying when I said they were not designed to do 1080P 72hz fully resolved, so there will be roll-off.

The AD834 is a better chip for first stage or pre-amplifier as you put it, and has an amazing flat response. But is a noisier chip to work with. It's higher bandwidth windows also allows hash or trash noise to be a problem, that usually shows on the screen as being a dust or cloud in the image. The stock neck boards will respond better to a flatter bandwidth than -3db though.

I really like reading your commentary and data on this stuff as I've told you before. Nothing you post is wishful thinking and that says a lot about you.

I think a little peaking can be a good thing... as long as the ringing can't be seen from the viewing position.

I had a ringing mod on the old Mitsubishi CRT projectors of which I literally calibrated over 1000 units. The video output amplifier had a peaking circuit built in and I would remove an inductor on their VNB and replace it with a variable inductor. I would then tune the inductor such that with a 30 IRE window pattern I could just start to see a bit of ringing right at the screen.

Those were the days...

craigr

_________________
JETI Specbos 1211 Spectroradiometer
Photo Research PR-650 Spectroradiometer
Klein K10-A Laboratory Grade Colorimeter
Murideo Fresco SIX-G HDMI 2.x Multimedia Generator
Murideo Fresco SIX-A HDMI 2.x Analyzer
*NEW Light Illusion LightSpace XPT Pro Version 10.x Color Calibration Software
ChromaPure3 Pro Color Calibration Software
Sencore CR7000 CRT Tube Analyzer / Rejuvenater
Audyssey MultEQ Pro Audio Calibration System
Authorized Dealer for Lumagen & just about everything else Wink
www.CIR-Engineering.com - craigr@cir-engineering.com
Phone: 865-405-6892
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mp20748



Joined: 12 Sep 2006
Posts: 5359
Location: Maryland

TV/Projector: 9500LC Ultra / Super 02 and 03 VIM


PostLink    Posted: Thu Sep 21, 2017 6:46 am    Post subject: Reply with quote

CIR Engineering wrote:
jbmeyer13 wrote:
Only thing I shoot screen shots of is test patterns because it's not dependent on a proper calibration. IMO, that is the only useful way to evaluate BW performance for a video chain. All other attributes have to be seen in person to understand the results. Getting a camera to come remotely close to displaying what is onscreen is not something I have interest in and is a hobby all to itself.

THANK YOU. I have said that so many times...

Thumbs Up
craigr



I always say they can only be used as an idea of what's on the screen, because there is no way you can involve cheap cameras and other processing in a accurate image evaluation. There are just far too many variables that will cripple any real results.

And as much as this has been mentioned over the years, yet over on another forum, there are almost weekly comparison shots of any shots I post, being side by side or top and bottom comparisons to show how much better one setup is to the other. And it goes further, they are now able to determine the amount of light output of my shots based of some strange science.. Rolling Eyes Rolling Eyes Rolling Eyes

It would be the equivalent of a bunch of Hi Fi enthusiast gathering in a room, to evaluate sound systems from around the world, by playing back and listening to what each individual recording captured on various and cheap audio recordings and using them for comparison.

_________________
We're no longer offering Mods. There are other options available from other sources these days. We are still supporting any previous work.
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gjaky



Joined: 05 Jun 2010
Posts: 2655
Location: Budapest, Hungary


PostLink    Posted: Thu Dec 14, 2017 8:12 pm    Post subject: Reply with quote

Out of interest I performed frequency response measurements on the ULTIMATE VNB-DB board. The response have some waviness but remains within a +/-2dB window throughout the end, and the -3dB roll off point is around 670MHz. That would be enough for 4K at any framerate... Laughing

AD834->2N3906->LMH6703 (with 430Ohm feedback resistors)



AD834_1.png
 Description:
Frequency response of the ULTIMATE VNB-DB
 Filesize:  9.97 KB
 Viewed:  5186 Time(s)

AD834_1.png



_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB
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View user's photo album (1 photos)
gjaky



Joined: 05 Jun 2010
Posts: 2655
Location: Budapest, Hungary


PostLink    Posted: Mon Dec 18, 2017 3:03 pm    Post subject: Reply with quote

Further experiments showed that increasing the feedback resistance of the opamp to 475 Ohm, the frequency response remained flat within +/-1.5dB up to 550MHz, with upper -3dB point at 610MHz „only”.


AD834_LMH6703_475R.png
 Description:
 Filesize:  10.04 KB
 Viewed:  5094 Time(s)

AD834_LMH6703_475R.png



_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB
Back to top
View user's photo album (1 photos)
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