[TechAssist] Re: NEC DT-4861S Projection TV goes into shutdown.
- From: "Peter oliver" <oliver_peter1@xxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Mon, 07 Oct 2002 03:29:54 +0000
Basic Physics sugests that you can't get more out than what goes
in..especially if you consider diode and line drops/attenuation but, if one
of the timming caps for the horizontal or another part goes bad ( either in
the drive or on the return side of the fbt {yoke or collector timing caps})
incressing the oscilation frequency it would corespondingly increse the
voltage out of the fbt. But immediate shutdown doesn't allow you to reach
steady-state on the electronics so you may be measuring the effect from the
startup pulse or it is dificlult to tell unless you are on at least for 2-3
sec. So my two best bets would be to measure the input b+ voltage and
mesure/Test etc the componets involved in timing the horizontal But that is
drawing from direct view sets since in the US NEC went out of the consumer
electronics business (TV,VCR..) about 10 years ago and stopped all parts
avalibility 3 years ago ( 7 years after last sales)
Peter Oliver
Tucson Radio TV
From: kevinstv <kevinstv@xxxxxxx>
Reply-To: techassist@xxxxxxxxxxxxx
To: TECH-ASSIST <techassist@xxxxxxxxxxxxx>
Subject: [TechAssist] NEC DT-4861S Projection TV goes into shutdown.
Date: Sun, 06 Oct 2002 18:43:15 -0700
NEC DT-4861S Projection TV goes into shutdown.
Hi fellow techs,
Working on this projection TV. After much head scratching and testing, have
discovered that this set is going into shutdown because of excessive HV.
Measured HV first coming out of flyback, but set shut down too quickly to
measure. Then days later (today, to be exact) measured HV coming out of HV
block or splitter and found it to be 35 KV, before it went into shutdown.
HV should be 31 KV from service manual. Is it possible for HV block to
produce more voltage than going in? Or is my flyback producing the
excessive HV? B+ is good. Is there any method to test the HV splitter out
of circuit? Thankyou.
Kevin Wilks
Kevin's TV and Video Repair
Penticton BC Canada
kevinstv@xxxxxxx
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