[TechAssist] Re: Samsung TXK2754 with repeat horizontal outputfailure
- From: "Christopher Barnak" <cbarnak@xxxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Wed, 18 Feb 2004 08:31:24 -0500
Bob,
I had that same problem with a different model Samsung. We have about 200
Samsung model TXB 2012 TV's in the school system. For some reason I had about
10 of these units continously being returned for blown HOT. I replaced
everything I could think of, but still these sets would always return. They
might work a week, month, or year, but they would ALWAYS return. Most did'nt
make it more than a month or two, and, it seemed like the HOT was blowing on
power on or off (which one, I'm not sure). It was driving me crazy. Then I
decided to lower the B+, an easy thing in this model. I replaced the STR30125
regulator with a STR30120. To my surprise, not one of these sets have failed
yet. But I still don't know why the extra +5volts made a difference. And why
the other 190 TV's don't have this problem. Now if I get a set in with a blown
HOT, I replace it with the 120V regulator as a precaution. Sometimes, things
are just too intermittent to troubleshoot and not worth the time unless you see
a string of them start coming in.
Christopher Barnak, CET
Norfolk Public Schools
School Plant Facilities
966 Bellmore Ave.
Norfolk, Va. 23504
Phone 757 628 3385
Fax 757 628 3392
cbarnak@xxxxxxxxxxxxx
>>> geminitv@xxxxxxxxxxxxxxxx 2/17/04 2:34:24 PM >>>
Yes I did the obvious! I did replace C414 (220mfd/35v) off the primary of
the horizontal driver transformer and also C427 (2.2mfd/250v) of the
horizontal yoke winding this morning. I had ordered a couple extra HOTs so I
put a new one in and the set is running. The question is for how long?
Bob Waterman, CET® #RI-28
Master Technician License #9109
Service Manager / Parts Manager
Gemini Computer, TV, & Security Alarms
(508)695-7302
(508)695-7769 FAX
geminitv@xxxxxxxxxxxxxxxx
geminitv@xxxxxxx
www.geminicomputertvsecurityalarms.com
----- Original Message -----
From: "Webster TV" <webstertv@xxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Tuesday, February 17, 2004 1:56 PM
Subject: [TechAssist] Re: Samsung TXK2754 with repeat horizontal output
failure
> Bob,
>
> Did you check the horiz. driver transformer for poor solder connections?
> Have run into this on numerous different brands, the unit will run
perfectly
> until the connection opens up and then the H.O.T. will short immediately.
> Just a thought if you haven't checked this.
>
> Dan Webster
> Webster's TV
> Shullsburg, Wi.
> ----- Original Message -----
> From: "Gemini Computer & TV" <geminitv@xxxxxxxxxxxxxxxx>
> To: "Techassist" <techassist@xxxxxxxxxxxxx>
> Sent: Monday, February 16, 2004 7:04 PM
> Subject: [TechAssist] Samsung TXK2754 with repeat horizontal output
failure
>
>
> > I currently have a Samsung TXK2754 that was serviced by another servicer
> in
> > the past about 4 or 5 times for a dead set according to the customer
(she
> > recently moved into my area). I found the horizontal output transistor
> > shorted and this had been replaced by the other servicer (I could find
no
> > evidence that any other parts had been replaced at any time). I ordered
> > parts directly from Samsung and installed them this past Thursday and
the
> > set ran continously until at least 1pm on Saturday when we closed (I
came
> in
> > this morning and found the unit dead again with the output transistor
> > shorted again). The B+ was rock steady at 135 volts, the horizontal
> waveform
> > was perfect, and the set was looking good prior to dying again. Here is
> the
> > list of parts I replaced:
> >
> > Q401 (HOT) (KSD5703, Samsung # 0502-001136
> >
> > T444S (Flyback) (FUH-29A001A, Samsung# AA26-00013A)
> >
> > D805 (135 V rectifier) (F10U60S, Samsung# 0402-001358)
> >
> > Does anyone have some suggestions as to why the HOT keeps shorting (and
it
> > is "normally" cool with no signs of overheating)?
> >
> > Bob Waterman, CET® #RI-28
> > Master Technician License #9109
> > Service Manager / Parts Manager
> > Gemini Computer, TV, & Security Alarms
> > (508)695-7302
> > (508)695-7769 FAX
> > geminitv@xxxxxxxxxxxxxxxx
> > geminitv@xxxxxxx
> > www.geminicomputertvsecurityalarms.com
> >
> >
>
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