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km987654
Joined: 25 Jul 2007
Posts: 2874
Location: Australia
TV/Projector: Barco BG809s
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| Posted: Sun Oct 05, 2008 8:07 am Post subject: Barco RGB Output Amps |
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Having all sorts of problems with the RGB Output Amps from my barco. The Amp part number is R762173 the 75mhz variety from an 801.
The problem is that the screen fills with the color of the tube (blue in this case) just like a raster showing scan lines. There seems to be no gain. I have made NO adjustments to the board or should I say boards as I have 3 in this condition.
These boards have been put into an BD1100.
I have swaped out the board and things have gone back to normal but as mentioned three of these boards have gone the same way.
Can they be repaired?? If so can anyone help with what to replace??
Thanks
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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| Posted: Sun Oct 05, 2008 11:39 am Post subject: |
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Are the amps the same on both boards the original and the new you want to add? not all op amps work with the same gain and you need to get data sheets for the original and then a data sheet for the other set. Also the rest of the video chain might not work with a new board, it may designed for the other board and not be compatible. I think Curt mentioned this to you in another post, boards from the newer Barcos cant be swaped into the old BD1100 like you have.
Athanasios
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km987654
Joined: 25 Jul 2007
Posts: 2874
Location: Australia
TV/Projector: Barco BG809s
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| Posted: Sun Oct 05, 2008 9:44 pm Post subject: |
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| Nashou66 wrote: | Are the amps the same on both boards the original and the new you want to add? not all op amps work with the same gain and you need to get data sheets for the original and then a data sheet for the other set. Also the rest of the video chain might not work with a new board, it may designed for the other board and not be compatible. I think Curt mentioned this to you in another post, boards from the newer Barcos cant be swaped into the old BD1100 like you have.
Athanasios |
Athanasios
The set is basically a BG800 with 9inch tubes. As I understand parts from an 800 or 801 are interchangable in the 1100. The barco spreadsheets indicate that this should be the case. Same chassis number, SMPS etc. I purchased all the RGB amps from Curt. When they arrived one was already in this condition but two others have gone the same way. Perhaps something else in the set is causing the problem. Can the amps be adjusted without damaging the tubes??
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Tom.W
Joined: 09 Mar 2006
Posts: 6635
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| Posted: Sun Oct 05, 2008 9:49 pm Post subject: |
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Do those use 2SK511's for video amps ?
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km987654
Joined: 25 Jul 2007
Posts: 2874
Location: Australia
TV/Projector: Barco BG809s
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| Posted: Mon Oct 06, 2008 1:07 am Post subject: |
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VPH06
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km987654
Joined: 25 Jul 2007
Posts: 2874
Location: Australia
TV/Projector: Barco BG809s
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| Posted: Mon Oct 06, 2008 8:50 am Post subject: |
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Ok during testing today something interesting. The tube with the suspect Amp went to normal for a while and then back to no gain. The tube also went very bright at which point I shut it down and put the old amp back in and all returned to normal.
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Ile
Joined: 09 Mar 2006
Posts: 1491
Location: Jyväskylä, Finland
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| Posted: Mon Oct 06, 2008 11:58 am Post subject: |
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Those 801 amps and 801 driver board have IBCL feed back circuit that lover gain when tubes are driven too hard. Amps sends IBCL signal to decoder board, that is decreasing gain when cathode is driven too hot signal. It might be that 801 amps (IBCL signal level) aren't compatible with 800 driver board. Can't remember does that 800 driver board have IBCL circuit at all.
You have to compare those IBCL circuits from both schematics.
Also decreasing contrast might help to lower signal level at cathode to level where IBCL wont cut signal.
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km987654
Joined: 25 Jul 2007
Posts: 2874
Location: Australia
TV/Projector: Barco BG809s
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| Posted: Tue Oct 07, 2008 12:40 am Post subject: |
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The 800 does have IBCL circuit. I have the 800 service documents and the RGB Output amp section does not provide a circuit diag but does describe IBCL.
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geisemann
Guest
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| Posted: Thu Oct 09, 2008 3:26 pm Post subject: |
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These boards are flakey. I have a few new ones.
The VPH06 chips always fail.
On the 800 they used a SCR that failed and you had to replace that.
IF you need some let me know I can get you a few.
www.eisemann-theater.com
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Tom.W
Joined: 09 Mar 2006
Posts: 6635
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km987654
Joined: 25 Jul 2007
Posts: 2874
Location: Australia
TV/Projector: Barco BG809s
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| Posted: Sat Oct 11, 2008 5:47 am Post subject: |
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| geisemann wrote: | These boards are flakey. I have a few new ones.
The VPH06 chips always fail.
On the 800 they used a SCR that failed and you had to replace that.
IF you need some let me know I can get you a few.
www.eisemann-theater.com |
Thanks for looking at this.
How much for three replacements and are you replacing with same part??
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