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spitz
Joined: 26 Oct 2007
Posts: 26
Location: Indianapolis, IN
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| Posted: Wed Dec 17, 2008 3:31 am Post subject: Barco retro g808s filament supply problem |
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Hi guys,
Have any of you run into filament supply problems on Barcos? I finished watching a movie last week on my retrographics 808s, heard a pop, and watched my picture fade out. I pulled out the DMM and found I had no filament supply. Pulled the SMPS, found a blown 'FIL' fuse, and thought this was going to be an easy one. I replaced the fuse, fired it back up, and the fuse blew immediately. 
The remote works fine, I've got all green LED's, and the HV crackles like it should. All the filaments on my tubes measure 2.9 ohms so they don't appear to be shorted. Seems like the SMPS has something blown on the filament regulator but I can't find any schematics for mine. BTW, its an R7621706. Schematics or thoughts on where to look would be much appreciated.
Thanks!
Matt
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Z-Photo
Joined: 07 Mar 2006
Posts: 2749
Location: Huntsville - Alabama
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| Posted: Wed Dec 17, 2008 2:28 pm Post subject: |
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Check the +17.5 voltage
_________________
Engineer by Day
Photographer by Night
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The Only GOOD AMPRO - is a Dead AMPRO.
wait - are they not all DEAD already?
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Wed Dec 17, 2008 3:14 pm Post subject: |
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No, that's not it. I can repair it if you get stuck.
Cheers!
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spitz
Joined: 26 Oct 2007
Posts: 26
Location: Indianapolis, IN
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| Posted: Sat Dec 27, 2008 2:50 am Post subject: re: |
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Thanks for the offer Curt. If this goes on too much longer though, the Marquee is going back on duty, possibly with the P16s out of this retro!
Next question: Can I safely power up an 808s (MEC tubes) with J2 (the 6-pin conn. with the filament supply, G1, and G2 on it) disconnected from one or all of the neckboards? Will that cause any damage? My current guess is one of the caps on the neckboards is starting to break down. Normally I troubleshoot those by pumping a bunch of current into the rail until the bad component starts smoking but I really don't want to risk burning a hole one of these neckboards.
-Matt
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Ile
Joined: 09 Mar 2006
Posts: 1491
Location: Jyväskylä, Finland
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| Posted: Sat Dec 27, 2008 11:10 am Post subject: |
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Disconnect both cables from neck board. I have also disconnected hv cable from that same tube, but I think it's not needed.
Check C210 from smps, it's for filament and could be shorted. R7621706 have adjustable filament, so I think there is also some other elcaps near C210 for filament.
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spitz
Joined: 26 Oct 2007
Posts: 26
Location: Indianapolis, IN
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| Posted: Sat Dec 27, 2008 11:33 am Post subject: neckboards |
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Thanks Ile. I think I'm down to the neckboards now. I pulled the SMPS, then fed the FIL rails with my bench supply. I can't go over 2V without pulling more than 2A so I'm wondering if C43 and/or C44 on the neckboards is starting to fail. If that's not it, about the only thing left is the filaments themselves and I REALLY hope that's not the problem!
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spitz
Joined: 26 Oct 2007
Posts: 26
Location: Indianapolis, IN
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| Posted: Sat Dec 27, 2008 1:55 pm Post subject: |
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Got it! C43 on the red neckboard was shorted. Sorry for all the long posts. A broken projector this close to New Year's Day isn't fun!
-Matt
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