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damien55
Joined: 20 Oct 2008
Posts: 101
Location: UK
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| Posted: Fri Feb 13, 2009 1:42 pm Post subject: BG808 - streaking problem - R7621735 |
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Hi,
I have a problem with My BG808 (not a S ). I just changed my 3 RGB amps because the old ones were not calibrated properly and had the abl broken.
I then Adjusted the G2 following the LED method and the picture is much better now with the new amps.
but now I have streaking in my picture. Is there a way to get rid of it or at least reduce the problem.
Thanks
Damien
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secstate
Joined: 20 Mar 2006
Posts: 720
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| Posted: Fri Feb 13, 2009 2:11 pm Post subject: Re: BG808 - streaking problem - R7621735 |
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| damien55 wrote: | Hi,
I have a problem with My BG808 (not a S ). I just changed my 3 RGB amps because the old ones were not calibrated properly and had the abl broken.
I then Adjusted the G2 following the LED method and the picture is much better now with the new amps.
but now I have streaking in my picture. Is there a way to get rid of it or at least reduce the problem.
Thanks
Damien |
If you are talking a horizontal streak when you have a bright spot over a darker (but usually not black) background then that is a known problem with those boards. It varies from projector to projector and tube to tube but is there to some extent in every Barco I have seen that uses those boards and MEC tubes. On my Data 808s (uses same neckboards more or less) it is hardly noticeable. The only solution I have seen is to disable the ABL by removing the circuitry (Ile did that). Another alternative, but more expensive and hard to find is to use the newer neckboards form a 1208s/2 or 808 Retrographics.
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damien55
Joined: 20 Oct 2008
Posts: 101
Location: UK
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| Posted: Tue Feb 17, 2009 12:03 am Post subject: |
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Hi,
I might be able to get some BG808S RGB amps (R762721) to put in my BG808.
I have a few questions related to that:
Is it possible?
Do I need to change other cards? (Analogue switch board R762719 from the "S" ?? or Driver board R762720 from the "S" ??)
Is it difficult?
Will this mod get rid of the streaking?
Thanks
Damien
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secstate
Joined: 20 Mar 2006
Posts: 720
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| Posted: Tue Feb 17, 2009 1:20 am Post subject: |
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| damien55 wrote: | Hi,
I might be able to get some BG808S RGB amps (R762721) to put in my BG808.
I have a few questions related to that:
Is it possible?
Do I need to change other cards? (Analogue switch board R762719 from the "S" ?? or Driver board R762720 from the "S" ??)
Is it difficult?
Will this mod get rid of the streaking?
Thanks
Damien |
The BG808S boards will not work, at least not without modification. You need the MEC 8" versions that, as far as I know were used only in the Barco 1208s/2 (and later models) and the Barco Retrographics 808s (which used MEC tubes unlike its front projection counterpart). The boards you are looking for are R762746. The pinout on the Sony tubes is different but modification may be possible. But I have never tried so I cannot comment.
For a non-S version I don't know I think it has been done. I had to make no modification to my Data 808s which came with same neckboard and streaking as your projector.
With the right boards the swap is easy. You basically remove the old amps and neckboard and the astig magnetic rings which need to be removed to install the extra bracket needed to support the new boards.
And yes this completely removes the streaking and increases your RGB bandwidth some (but I don't buy Barco's specs as the difference between the two boards resolution wise was less than I would have expected).
As I said I did this mod using the R762746 boards and it was very easy and worked perfectly on my Data 808s.
As far as I know this and removing the ABL are the only two options that work (other than getting a new projector).
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damien55
Joined: 20 Oct 2008
Posts: 101
Location: UK
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| Posted: Tue Feb 17, 2009 1:39 am Post subject: |
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Thanks again for your help secstate,
The amps I could get are the R762721 and not the R762746 you are talking about. Is that a problem?
I guess you mean that the R762721 would only work on the sony tubes.
Thanks
I guess I'll have to wait for a set of R762746 from a retro or a 1208s/2
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secstate
Joined: 20 Mar 2006
Posts: 720
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| Posted: Tue Feb 17, 2009 2:02 am Post subject: |
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| damien55 wrote: | Thanks again for your help secstate,
The amps I could get are the R762721 and not the R762746 you are talking about. Is that a problem?
I guess you mean that the R762721 would only work on the sony tubes.
Thanks
I guess I'll have to wait for a set of R762746 from a retro or a 1208s/2 |
The R762721 is essentially the same as the R762746 with the exception that the tube socket is wired differently. So yes unless you rewire the tube socket, the R762721 will only work with Sony tubes which is what came in the BG808s. The R762721 are much easier to find because folks tend to part out the Sony tubed projectors because the tubes are so hard to find. You can find the R762746 your are looking for from time to time on Ebay (assuming Curt has no stock).
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Ile
Joined: 09 Mar 2006
Posts: 1491
Location: Jyväskylä, Finland
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damien55
Joined: 20 Oct 2008
Posts: 101
Location: UK
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| Posted: Tue Feb 17, 2009 10:41 am Post subject: |
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Thanks Ile and secstate for your help,
PS: Ile, you have a pm
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Decibel
Joined: 31 May 2007
Posts: 904
Location: Roma - Italia
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| Posted: Sun Apr 05, 2009 6:23 pm Post subject: |
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If you want change R7621735 RGB amps (75 mhz) with R762721 boards (120 mhz) you MUST (!!!!) to modify pinout because they're different.
For fully working of modify you must swap these boards also:
R7622685 ----> R762808 (Sync + Vertical Deflection)
R7621745 ----> R762719 (Quad Decoder. + RGB Amp + Input Switch)
R762546 ----> R762720 (RGB Driver)
R7621735 ----> R762721(mod) or R762746 (RGB Out 120 MHz)
You must to swap Eprom Ver. 7.XX in controller board
In the photo you can see newer version of convergence driver also.
sorry for language 
_________________
Domenico (Barco fan!)
Last edited by Decibel on Sun Apr 05, 2009 11:12 pm; edited 1 time in total
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RogueChili
Joined: 31 Mar 2008
Posts: 162
Location: Westfield, MA
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| Posted: Sun Apr 05, 2009 8:28 pm Post subject: |
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More streaking problems, I thought that was unique to 1292's. Is there a schematic available for the neck board? I have some experience tracking down streaking problems and would like to take a look.
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Ile
Joined: 09 Mar 2006
Posts: 1491
Location: Jyväskylä, Finland
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| Posted: Mon Apr 06, 2009 7:47 am Post subject: |
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| RogueChili wrote: | | More streaking problems, I thought that was unique to 1292's. Is there a schematic available for the neck board? I have some experience tracking down streaking problems and would like to take a look. |
Here's rgb amp schematics and my solution was to remove ABL to get rid of streaking.
http://www.curtpalme.com/forum/viewtopic.php?p=154857#154857
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RogueChili
Joined: 31 Mar 2008
Posts: 162
Location: Westfield, MA
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| Posted: Wed Apr 08, 2009 1:55 am Post subject: |
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| Ile wrote: | | RogueChili wrote: | | More streaking problems, I thought that was unique to 1292's. Is there a schematic available for the neck board? I have some experience tracking down streaking problems and would like to take a look. |
Here's rgb amp schematics and my solution was to remove ABL to get rid of streaking.
http://www.curtpalme.com/forum/viewtopic.php?p=154857#154857 |
Ile, is there any reason to restore the ABL? Looking at the schematic I notice the drive circuit suffers from a similar defect as the 1292 that can cause ringing on the sync pulse. The 1292 streaking mod addresses this issue and was designed to fit either the 1292 or the G90 however it may be possible to accommodate the 808. Just a thought..
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AnalogRocks
Forum Moderator
Joined: 08 Mar 2006
Posts: 26706
Location: Toronto, Ontario, Canada
TV/Projector: Sony 1252Q, AMPRO 4000G
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| Posted: Wed Apr 08, 2009 2:19 am Post subject: |
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I wonder if your streaking mod can be added to my RCA RPTV? It streaks so much on dark scenes it can make you blush.
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HD done right!
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Elaine Benes
Joined: 25 Apr 2006
Posts: 1416
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| Posted: Wed Apr 08, 2009 3:03 am Post subject: |
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Just wanted to add there were some BG808S's built with the 120Mhz neckboards and Panasonic tubes. I have one. It was a SEOS projector that I've converted back to normal. I guess all these fancy boards in it explains why its so damned sharp...
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Ile
Joined: 09 Mar 2006
Posts: 1491
Location: Jyväskylä, Finland
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| Posted: Wed Apr 08, 2009 8:40 am Post subject: |
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| RogueChili wrote: | | Ile, is there any reason to restore the ABL? |
Haven't found any good reason to have ABL.
G2 adjustment don't have those fancy leds anymore, but those wasn't very accurate in old sets.
I also think that removing ABL also bump BW bit higher.
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secstate
Joined: 20 Mar 2006
Posts: 720
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| Posted: Wed Apr 08, 2009 12:14 pm Post subject: |
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| Elaine Benes wrote: | | Just wanted to add there were some BG808S's built with the 120Mhz neckboards and Panasonic tubes. I have one. It was a SEOS projector that I've converted back to normal. I guess all these fancy boards in it explains why its so damned sharp... |
It is the high resolution CRTs more than anything. With the exception of the neckboards the video chain in a BG808s is the same as a Data 808s. The post above is how to mod a non-S to S projector. The video chain is improved on the S models but with the exception of the SEOS units and late model Cine projectors, the 8 series projectors did not get those high resolution tubes (they were installed in most S model 1208s). I swapped the 120 MHz neckboards into my Data 808s and it did get rid of the streaking but otherwise the effect was very subtle. Except on the computer desktop and video you would have never noticed the difference but for the streaking.
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