[TechAssist] Re: Envision Flat Panel Monitor
- From: peggs <peggs@xxxxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx, <techassist@xxxxxxxxxxxxx>
- Date: Thu, 06 May 2004 10:57:04 -0700
I'm now thinking I have some sort of Logic problem.
It's back to the Power light coming on automatically,most times Yellow but
sometimes Green,and it won't turn off by the Power Switch.
Also no Video,and the Screen doesn't light-up OR
Flash at all(which it did yesterday).
I don't have anywhere near 200-250 volts going IN to the Lamp PCB.
I see the DC-DC section on the Lamp PCB,but my only plug going TO this
PCB has 3.3v,and (2) 12v supplies.
The B+ Supply to this Monitor is a 12v supply.It comes in to the
Main/Power Supply PCB and feeds a
AIC
1084-33CM
103F1
which I think is a 3.3v regulator.
The 12v also feeds a
XM21AC
LM2596s
which I think is a 5v Regulator.
If I'm right about these regulators,their voltages are fine.
I've tried unpluggiong the Input to the Lamp PCB to see if the Logic(Power
Switch)
would Turn the unit On and Off properly,but I have the same symptom.
I found a 'borderline' SM capacitor,replaced it,but I have the same symptoms.
Peggs
At 05:27 AM 5/6/04, Damon wrote:
>I think you can use your scope probe to pick up the DC-DC pulse generated
>from the ballast/driver board...just like they do with IHVT pulses on the
>transformer....I've seen on most units a spark gap that fires during start
>up but I'm working on Sony, Phillips, and Samsung units, not Envision...
>
>And since MOST boards look like they came out of a Sony....I suspect one or
>two suppliers/builders of the board, same with the lamp, just different lamp
>frames and lamp sizes/shapes. Sure wish they'd REALLY universal-ize the
>Lamps, I'd carry one or two on the truck then....
>
>Anyways back to your problem.....you can ONLY test the input voltage to the
>Ballast/driver board, and I would expect around 200 - 250 volt input.
>Normally after the fans start, you will see or hear a spark gap fire on the
>lamp driver board, fires at a quick rate for about 2-3 seconds,
>pauses....fires another 2-3 seconds....If you don't see/hear this, then just
>replace the Lamp driver board, but I see MORE LAMPS BAD than LAMP DRIVER
>BOARDS.
>
>----- Original Message -----
>From: <majorthom@xxxxxxxxxxxxx>
>To: <techassist@xxxxxxxxxxxxx>
>Sent: Wednesday, May 05, 2004 11:02 PM
>Subject: [TechAssist] Re: Envision Flat Panel Monitor
>
>
>| Careful of lamp voltages as they're in KV -they are generated by a DC/DC
>convertor ckt w/overload shutdown[protection] I have this model in shop and
>gave up on it temporarily,As far as customer support Envision is cool KDS
>sucks.AS to the specifics of why ask and I'll tell you.How are we ddoing so
>far...Pete
>| peggs <peggs@xxxxxxxxxxxxx> wrote:The main PS board is part of the Main
>PCB(i hope that made sense:-)
>| There are a few Radial Caps,but they ESR fine.
>| There are also some SM Caps I've yet to check.
>| The other board in here is the Lamps Driver/PCB.
>| Any ideas what voltages I should be looking for on the Lamp PCB ???
>|
>| Peggs
>|
>| At 05:46 PM 5/5/04, Jim Shupe wrote:
>| >Peggs...
>| >
>| > I would warm the thing's power supply slowly and
>| >observe for any changes in symptoms...if there are
>| >then you know you should ESR all the caps.
>| > Nowadays, I find that the most common component
>| >failures are electrolytic capacitors leaking and
>| >drying out.
>| >...just my two cents.
>| >
>| > Jim Shupe, CET
>| > Lloyd's TV
>| > Yucca Valley, CA
>| >
>| >peggs
>| wrote:My first flat panel
>| >to work on.
>| >model EN-7100s
>| >FCC ID: ARSLM782T
>| >This thing has 5 warranty stickers inside here.#6 is
>| >on the Back.
>| >I guess they were expecting in-warranty troubles.
>| >Anyway,when it was dropped off,we hooked it up and it
>| >was
>| >stuck in stand-by(yellow power light) and couldn't
>| >turn it off.
>| >Now,with the back removed Power light comes on and off
>| >properly,but still
>| >it's stuck in the stand-by mode,with a slight Flash by
>| >the Screen periodically.
>| >
>| >I don't know what the Voltages should be on the Lamp
>| >or on the PCB that
>| >drives it.
>| >Would this Lamp cause it to stay in stand-by ???
>| >
>| >Peggs
>| >Peggs' Electronics
>| >1519 West 2nd Street
>| >Owensboro,KY 42301
>| >270-926-4968
>| >fax 270-686-7399
>| >peggs@xxxxxxxxxxxxx
>| >
>| >
>|
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>| Peter Neal
>| Neal Electronics
>| 1905 E. Wm.Cannon
>| Austin,TX 78756
>|
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