[TechAssist] Re: Zenith 27" TV - SF5729W2 - C3 - Other Problems
- From: Al Gutz <alg@xxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Fri, 06 Feb 2004 22:53:36 -0500
David
With the set pluged in not turned on measure volts on C and B of horz
dirver trans, should be zero.
Since the horz driver transformer was burned I suggest you replace
QX3401 2n3904. You may already have damaged the horz transformer you
replaced.
Al G
Al's TV-Electronics
Pembroke Ont.
Canada
David Lessard wrote:
>
> This TV is half alive and possessed. The SMPS was always working the
> entire time and not the problem; I can see that another tech had done
> the 3.3uf & 10uf cap replacement in the SMPS circuitry.
>
> A fellow tech sent me a schematic of the sweep and SMPS circuits and the
> hunt was on. At first I thought I had horizontal pulses, well, at least
> coming out of the jungle IC however the pre-driver transistor, the one
> that drives the horizontal output transformer was open between the base
> and emitter. I temporarily replaced that with an ECG399 (it's all I had)
> and good pulses were present at the primary of the transformer but there
> was little pulses (less then half a volt) at the secondary where it
> drives the HOT, possible shorted (intermittent) secondary so I swapped
> it with another similar one (but not the exact replacement) and the TV
> came on, it sort of surprised me because there was a 1-2 second delay
> after the ON button was pressed, probably caused by the characteristics
> of the transformer, not really sure.
>
> Anyway this TV has other problems; first the picture width fluctuates
> slightly every once and awhile. The raw +B seems to fluctuate in sync
> with the horizontal width fluctuations. Also, and this problem is the
> possessed part, the TV when first plugged in makes a few speaker noises,
> buzzing and popping and occasionally you can hear the audio from the
> tuned channel coming out of the speakers but the TV is not turned ON.
> Question: When this TV is first plugged in you can hear a relay click,
> is this normal? Then the intermittent buzzing and noises start, etc.
>
> Sorry for the lengthy follow-up report but I'm really trying to learn
> more about this chassis. Thanks for all the help so far.
>
> David Lessard
> Alexandria Electronics
> 50 Harrison Street
> Alexandria, Ontario
> K0C-1A0
> mr_fixit@xxxxxxxxxxxx
>
>
> -----Original Message-----
> From: techassist-bounce@xxxxxxxxxxxxx
> [mailto:techassist-bounce@xxxxxxxxxxxxx] On Behalf Of Intrepid Video
> Support
> Sent: Wednesday, February 04, 2004 6:21 PM
> To: techassist@xxxxxxxxxxxxx
> Subject: [TechAssist] Re: Zenith 27" TV - SF5729W2 - C3
>
> David,
> >From Tech Repair CD:
> ZENITH\SF5729S\RELAY CLICKS* WON'T POWER UP* GETS WORSE WITH
> TIME\\\\C3407(100/25V) ON POWER PCB-BESIDE
> LARGEST CAP\\\\\\\\
>
> Jeff Dougherty
> Intrepid Video TV/VCR
> 263 S Front St
> Steelton PA 17113
> fax...717-564-4952
> www.intrepid-video.com www.tech-repair.net
>
> ----- Original Message -----
> From: "David Lessard" <mr_fixit@xxxxxxxxxxxx>
> To: <techassist@xxxxxxxxxxxxx>
> Sent: Wednesday, February 04, 2004 3:34 PM
> Subject: [TechAssist] Re: Zenith 27" TV - SF5729W2 - C3
>
> This TV is on the bench now. When first plugged in, relay clicks, then a
> soft buzzing sound is heard from speakers. I can turn the TV off using
> the ON/OFF button on the front panel but can not turn the TV back on,
> must unplug set. I've changed the caps in the SMPS with no change. +B in
> standby is +135V and +140V with the set turned ON. Horizontal drive
> pulses are present, +B 140V present at HOT. Occasionally while this TV
> is powered ON you can hear the audio buzz and click come and go. I have
> no idea what is going on here. Any help would be appreciated as I don't
> work on many Zeniths.
>
> Thanks in advance,
>
> David Lessard
> Alexandria Electronics
> Alexandria, Ontario
> K0C-1A0
> mr_fixit@xxxxxxxxxxxx
> > ---Good luck---
> >
> > I don't like the sounds of that, is this going to be a dog? I don't
> work
> > on many Zenith TV's around here. Does anyone have information on this
> > chassis: dead with just a clicking relay when switched on and off. God
> > Bless America (North and South)!
> >
> > Thanks in advance
> >
> > David Lessard
> > Alexandria Electronics
> > Alexandria, Ontario
> > K0C-1A0
> > mr_fixit@xxxxxxxxxxxx
> >
> >
> > -----Original Message-----
> > From: techassist-bounce@xxxxxxxxxxxxx
> > [mailto:techassist-bounce@xxxxxxxxxxxxx] On Behalf Of Bill Grabowski
> > Sent: Monday, February 02, 2004 5:39 AM
> > To: techassist@xxxxxxxxxxxxx
> > Subject: [TechAssist] Re: Zenith 27" TV - SF5729W2 - Chassis# ??
> >
> > It's a C3 chassis using a 9-825-01 for main and 9-822-01 for Hor/Vert
> > sweep and SMPS........GoodLuck.......
> >
> > Bill Grabowski
> > Triangle Appliance
> >
> > David Lessard wrote:
> > > Does anyone know what the chassis number is for this model? I'm
> trying
> > > to gather some information before visiting the customer. TV is dead,
> > > that's all I have. Are there any common problems for this model
> being
> > > dead?
> > >
> > > Thanks in advance,
> > >
> > > David Lessard
> > >
> > > Alexandria Electronics
> > > 50 Harrison Street
> > > Alexandria, Ontario
> > > K0C-1A0
> > >
> > > mr_fixit@xxxxxxxxxxxx
> > >
> > >
> > >
> >
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> > --
> > *****************************
> > Bill Grabowski
> > Triangle Appliance
> > Kenosha,Wi 53142
> > 262-694-6500
> > 262-694-6523 fax
> > bgrabowski@xxxxxxxxx
> > *****************************
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