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PJMoore
Joined: 05 Oct 2006
Posts: 99
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| Posted: Sat May 03, 2008 6:02 pm Post subject: Meter testing Marquee HVPS? |
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I am going over to help a friend troubleshoot his dead marquee. Is there a place I can meter to see if the LVPS and or HVPS is functioning using a Fluke DVM? I know I read about thisa recently on the forum, but I sure can't seem to locate it again. It was describing what voltage to expect at what location for various values of G2 and drive as I recall. My searches have been fruitless so far.
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Tim in Phoenix
Joined: 21 Oct 2006
Posts: 4409
Location: Phoenix
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| Posted: Sat May 03, 2008 6:34 pm Post subject: |
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Troubleshooting Marquee Video Problems Without A Scope
One does not always have the luxury of a dual trace scope on the road,
here are a few norms to test for if your Marquee has high voltage and
picture problems, like flashing, or no pix at all:
Vim Mini Coax Levels, Unplugged From VNB:
With CONT of 40 and BRITE of 40, the tip of the mini coax feed
gives 110mv with internal stairstep, 255mv on white field.
Internal Pattern Sequence is 1) Hatch plus Dots,
2) Dots Only, 3) Stairstep, 4) Full White, 5) Source
G2 Values and Voltage, measured at tip of VNB R76:
G2 of 40 gives +375vdc
45 +415vdc
50 +462vdc
55 +510vdc
60 +555vdc
65 +600vdc
70 +646vdc
Fluke DVM dc limit is 655vdc and goes into alarm mode.
Brightness Control Line to VNBs, P13 Pin 8:
BRITE of 0 gives +2.02vdc
10 +1.59vdc
20 +1.19vdc
30 +0.81vdc
40 gives +0.37vdc
50 - 0.02vdc
60 -0.44vdc
We have observed Marquees with leaking glycol where this control
voltage was shorted to +5v on the MB and as a result the tubes shut
down for no apparent reason; you would think you had a bad VIM
or neckboard but it was not so.
Tim at E-Tech Systems 480 368 7434 http://www.etechvideo.com/
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Tom.W
Joined: 09 Mar 2006
Posts: 6635
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Tom.W
Joined: 09 Mar 2006
Posts: 6635
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PJMoore
Joined: 05 Oct 2006
Posts: 99
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| Posted: Sat May 03, 2008 8:04 pm Post subject: |
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Got it - it was Tim's post. Thanks to Tim and Tom both!
now as Mr. Natural said: "Onward - into the fog!"
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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: Sat May 03, 2008 9:34 pm Post subject: |
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From what I\ve seen, the G2 starts in the sealed HV section of the block, so if you have good G2 voltages, then your HV should be OK too.
I'd pay money for a test jig to fire up a MArquee HVPS outside of the chassis, I should look into making that...
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PJMoore
Joined: 05 Oct 2006
Posts: 99
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| Posted: Sat May 03, 2008 9:54 pm Post subject: |
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and thanks as well to Curt, of course.
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Tim in Phoenix
Joined: 21 Oct 2006
Posts: 4409
Location: Phoenix
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| Posted: Sun May 04, 2008 12:35 am Post subject: |
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| Curt Palme wrote: |
I'd pay money for a test jig to fire up a MArquee HVPS outside of the chassis, I should look into making that... |
An Amphenol edge connector or part of the Marquee internal harness, the rearmost half inch from a dead hvps board, a spool of 20 gauge hookup wire and your soldering iron should handle it.....
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Tom.W
Joined: 09 Mar 2006
Posts: 6635
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