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zenith t.v. model # pv4655lk9

Discussion in 'Electronic Repair' started by CTORO, Jul 26, 2005.

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  1. CTORO

    CTORO Guest

    i have no picture, after it was on for about a month...I just go
    it...then the picture went out...i still have sound....anyone out ther
    familiar with these types of t.v.'s
     
  2. bz

    bz Guest

    I am working on a different zenith with same symptoms.
    There is a solder in, 2 amp fuse that feeds dc to the HV/horizontal
    section. Mine is blown, and blows immediately when I replace it.

    An online database says I should replace the flyback.
    If the fuse were not blown, there are a couple of solder connections and a
    diode, and a capacitor that they recommend replacing.




    --
    bz 73 de N5BZ k

    please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
    infinite set.

    remove ch100-5 to avoid spam trap
     
  3. It has sound with no horizontal output? That's rare...

    Tom
     
  4. bz

    bz Guest

    Why am I so lucky as to get the 'rare ones'?

    1993 Zenith TV. model number SL3585BT (zenith C8 Chassis)
    Serial Number 381-34431174
    Blows FX3403 (2A) fuse in HV / horizontal circuit.
    I do not have a schematic. None are available [so zenith says].
    the board has the number 204-2755-09 on the edge.
    http://www.euras.com/repair_tips_1/Zenith/SL3585BT/SL3585BT_Zenith.htm
    Suggests 'replace flyback transformer'
    I am looking for replacement flyback or an exchange on the entire board.

    --
    bz 73 de N5BZ k

    please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
    infinite set.

    remove ch100-5 to avoid spam trap
     
  5. Andy Cuffe

    Andy Cuffe Guest


    Have you checked the horizontal output transistor?
    Andy Cuffe

    <-- Use this address until 12/31/2005

    <-- Use this address after 12/31/2005
     
  6. bz

    bz Guest

    Not yet. Any idea where / which one it is? No schematic.

    I have been poking around with a curve tracer and haven't found any obvious
    problems.




    --
    bz

    please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
    infinite set.

    remove ch100-5 to avoid spam trap
     
  7. Guest

    Whoa, wait a minute. You are poking around a tv set and cannot
    identify the horizontal output transistor?

    Please pick up any book on tv repair (post 1985) and do a good quick
    reading before you go any further. People here can help, if you have
    some basic understanding of what you are looking at inside the tv set.
    www.repairfaq.org might also be of some use. I am sure any community
    college library that offers vocational electronics will have one
    available.

    The module number that is on the board starts with a 009-xxxxx-xx
    number and is usually on a label somewhere near the system controller
    ic. In case you cannot find the module number, download z-tips here:
    http://orpheuscomputing.com/technicians/tech_downloads.html and look up
    the model number. There may even be some specific tips for that
    chassis.

    It might be cost/time effective to send the module out to PTS for them
    to repair it. At least check on the price. Sometimes on the older
    Zenith modules with limited parts availability, they are the least
    troublesome way to get the tv repaired.

    One thing that comes to mind is the pin and horizontal shaping coils,
    as I remember one of those commonly goes bad in that set and takes out
    several other parts.
     
  8. bz

    bz Guest

    Being able to 'guess' which one it is and knowing are two different things.
    I have 'some idea' of the basics, Texas Electronics Association Certified
    Electronic Technican #TEX-173 in audio, radio-TV and industrial electronics.
    I used to have an fcc 1st phone and 2nd telegraph license w/ radar
    endorsement. I owned a shop in Texas in the early 70s.
    TVs have changed a bit since I was working on them every day.
    I will check.
    Will look again.
    Some interesting information:
    C8 chassis
    service manual CM-145
    9-1270-02 HOR/VERT Sweep & SMPS
    a few. No pictures so far.

    C8-L series [no idea which series I have, yet]

    location TX3204 (95-4134-09)
    REPLACE FLYBACK WITH PART# 95-4134-11. PARTS INFORMATION SHOWS REPLACEMENT TO
    BE A -10. THIS IS WRONG.
    The set was working normally one moment and the picture disappeared.
    Sound still ok. No HV, no raster, the 2 amp fuse blown. Replacement blows
    immediately.

    Thanks for the info.


    --
    bz

    please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
    infinite set.

    remove ch100-5 to avoid spam trap
     
  9. kip

    kip Guest

    Take the TV to a shop and get an estimate before you kill yourself.

    It definitely shows that you don't have a clue as to what you are doing.



    jmo
    kip
     
  10. bz

    bz Guest

    Have you ever taken a 48 inch tv anywhere? Last time I tried to move the
    thing, with three helpers, it almost killed us.
    I taught basic electronics, Radio TV repair, and Avionics in the early 70s.

    Top posting your comments shows you don't know how to use usenet. You also
    missed my 05:54 reply to dkuhajda, which would have set your mind at rest
    as to my killing myself.

     
  11. kip

    kip Guest

    Yes I move Pro Sets every week Thats My Job...
    Call somebody in for an estimate of costs...Then you will know.

    kip
     
  12. bz

    bz Guest

    Thank you for your advice.




    --
    bz 73 de N5BZ k

    please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
    infinite set.

    remove ch100-5 to avoid spam trap
     
  13. bz

    bz Guest

    My first guess is QX3208, but, as I said, I don't have a schematic.

    I am 'poking around' with a simple curve tracer that applies an ac voltage
    across the device under question. One axis on the scope shows the voltage
    across the device, the other shows the current through it [as sensed across
    a series resistor]. I built it from an article in a radio tv mag back in
    the early 70s. I used it for a lot of trouble shooting when I was fixing
    radar and other equipment on ships and boats on the mississippi in the mid
    70s and later when I was doing board repair on minicomputer and instruments
    in the late 70s. Often you can test 'in circuit' with it. Sometimes, when a
    low resistance/inductance or high capacitance is in the circuit, you need
    to cut traces or unsolder stuff.

    Anyway, That is what I am using to troubleshoot the chassis, which I have
    pulled out of the TV.
    The only such number I see is on a paper tag on the OTHER board.
    9-1235-2

    That board has the tuners and controller stuff. I haven't looked at it
    carfully.
    It sould SURE help to have a road map, layout and schematic. Surely someone
    has such for the zenith C8 chassis.

    I have fixed many things without schematics, but I hate it.



    --
    bz

    please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
    infinite set.

    remove ch100-5 to avoid spam trap
     
  14. Guest

    Since your experience is pre-1985 you are probably use to working with
    a separate high voltage output tube and/or a horizontal output tube.
    You should know what a flyback is even from that experience.

    Most tv sets from the early 1980s up to but not including the tv sets
    that use high scan technology, HDTV, use a common horizontal output
    transistor to generate the horizontal sweep and the high voltage
    through the flyback. You should be able to identify it by finding the
    larger transistor (as it needs to pass a lot of current 1.0 amps and
    some rf and the horizontal sweep) that is on a heatsink near the
    flyback. In fact the collector of the transistor will be directly
    connected to one pin of the flyback.

    I think Sams photofacts lists most all Zenith models and chassis:
    http://www.samswebsite.com/
    You can also see if your local library in your nearest large city has
    those in the reference section. Many libraries do have Sams
    subscriptions and you can photocopy the sections you need.

    FYI the horizontal output transistor need only be checked C-E junction.
    They cannot be checked normally all the way around as there is an
    internal 40 ohm resistor between the B-E junction.
     
  15. bz

    bz Guest

    We had both tube and transistor TVs back in the 70s.

    Both solid state HV Rectifiers and Vacuum Tube HV rectifiers.

    The HV was rectified from the flyback transformer. No separate supplies in
    any TV I have ever seen, including some old, round CRT, B/W TV's I salvaged
    as a kid, collecting parts.
    Certainly. They are hard to miss. They kind of 'reach out and grab your
    attention'. :)
    There are several.

    Good hint.
    They didn't list the model number SL3585BT. I asked.

    They may have the zenith C8 Chassis.
    I live in Baton Rouge, LA.
    I even called zenith. When I got past their 'we only sell to technicians',
    I got 'that manual is no longer available'.
    THAT is important to know. Thanks.
    I would have said 'bad transistor'.


    --
    bz 73 de N5BZ k

    please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
    infinite set.

    remove ch100-5 to avoid spam trap
     
  16. Sorry...a 1993 TV with no H output should not have audio.

    Tom
     
  17. bz

    bz Guest

    Apparently this set doesn't know the rule.
    http://www.euras.com/repair_tips_1/Zenith/SL3585BT/SL3585BT_Zenith.htm
    lists 'has audio, no raster, no HV' as one of the possible symptoms.

    The set has three different fuses. The one that is blowing IS NOT the main
    fuse.

    Do you have the Zenith C8 Chassis schematic and or roadmap?




    --
    bz

    please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
    infinite set.

    remove ch100-5 to avoid spam trap


    --
    bz 73 de N5BZ k

    please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
    infinite set.

    remove ch100-5 to avoid spam trap
     
  18. Guest

    Since that set was a module level repair under warranty and the module
    cost up until recently was low enough that component level repair would
    cost more in time and effort for the big failure, many shops simply did
    not bother with the full service manual/schematic set.

    The H.W.Sams reference should come up with the CM-145 chassis
    designation.
    Realize that it might not be 100% exact as Zenith would use the basic
    same chassis and make some changes for specific models.

    http://www.ptscorp.com/ should be able to get you a repaired module.
    They also have a tech tip section and on the C8 chassis it indicates
    that the picture tube should be checked as a G1 short can damage the
    power supply. In every case of the horizontal output transistor B+
    fuse going open with a good flyback and shaping coils wound up being a
    bad picture tube, in the 32" and 35" Zeniths.

    The big picture tube failures Zenith had was the 25" and 27" size
    tubes, but I did see a few (less than 5) on the larger tube sizes.
    It might be beneficial to get a hold of a good recent crt tester and
    verify the picture tube before spending too much time on the set.
     
  19. bz

    bz Guest

    Found several C8 chassis under cm145. I just ordered the microfisch for A and
    C. Hope that will be close enough. Will have to scan the fisch when I get it
    so I can read the thing. Oh well. Cheaper than paper. Too bad they don't
    have on line for download.
    :) or too much money. I doubt it is worth replacing the Picture tube.


    Sounds like good advice. I thank you!

    A G1 short should show up with an ohm meter check, shouldn't it?




    --
    bz

    please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
    infinite set.

    remove ch100-5 to avoid spam trap
     
  20. I saw a Philips that would do the same also, some years back.
    Generally, though, TV's have most supplies derived from the H
    scan...no H, no power. Even those with switching supplies usually will
    not have power when the horizontal is out.

    Tom

    Tom
     
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