Funny repeat problem with a 60 inch RCA PTK195AC (model P60812BL)

Discussion in 'Electronic Repair' started by eganders@yahoo.com, Jan 4, 2006.

  1. Guest

    This is a continuing saga of a 60 inch rear projection RCA TV. It has
    a chassis number of
    PTK195AC and is model P60812BL. I have now had a repair technician
    over and it worked like a charm while he was here and for a couple of
    hours after he left. Then it returned to the absolutely black picture
    it had when the problem first surfaced a few days ago. The repair
    technician feels he should change the EPROM. Can an EPROM problem
    result in NO output from a projection tube?

    This is the sequence of events.

    The other day one minute it was working perfectly (as it has for 8
    years). All of a sudden I walked into the room and the screen is black
    (none of the projection tubes are putting out any light).
    Turning it off, using the DVD and many other attempts to get a picture
    failed. I let it stay off for a while, then turned it on. It would have
    a
    picture for a short time that looked like an old 60's horizontal hold
    problem with a partial, shrunken picture. After a while the picture
    would be stable enough to be able to read letters, but totally
    distorted. I was afraid to leave it on long figuring I might stress
    the conditon. I called a repair technician and he came over today.

    The repair technician went into the service mode of the TV and changed
    a number of parameters stored in the EPROM and finally got it looking
    as good a new. He also used an external alignment generator and the
    grid looked straight and proper. Colors were true and bright. As I
    said, this lasted about a couple of hours after he left and then the
    screen went black (non of the projection tubes are generating any
    output) which is exactly the condition that happened when the problem
    first started. The filaments in the projection tubes glow and the
    sound and power-on sequence is just as it should be. So far I have
    not been able to get any type of picture back. I tried to get into a
    service mode per the instructions to push the menu power and +vol
    button. I have no picture and that did not give me one to be able to
    see any setup procedure. Again, would a bad EPROM result in NO output
    from the projection tubes?


    Anyone have any ideas where to start?
    , Jan 4, 2006
    #1
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  2. Asimov Guest

    "" bravely wrote to "All" (03 Jan 06 18:26:35)
    --- on the heady topic of "Funny repeat problem with a 60 inch RCA PTK195AC
    (model P60812BL)"

    eg> From:
    eg> Xref: core-easynews sci.electronics.repair:353850

    eg> This is a continuing saga of a 60 inch rear projection RCA TV. It has
    eg> a chassis number of
    eg> PTK195AC and is model P60812BL. I have now had a repair technician
    eg> over and it worked like a charm while he was here and for a couple of
    eg> hours after he left. Then it returned to the absolutely black picture
    eg> it had when the problem first surfaced a few days ago. The repair
    eg> technician feels he should change the EPROM. Can an EPROM problem
    eg> result in NO output from a projection tube?

    eg> This is the sequence of events.

    eg> The other day one minute it was working perfectly (as it has for 8
    eg> years). All of a sudden I walked into the room and the screen is
    eg> black (none of the projection tubes are putting out any light).
    eg> Turning it off, using the DVD and many other attempts to get a picture
    eg> failed. I let it stay off for a while, then turned it on. It would
    eg> have a
    eg> picture for a short time that looked like an old 60's horizontal hold
    eg> problem with a partial, shrunken picture. After a while the picture
    eg> would be stable enough to be able to read letters, but totally
    eg> distorted. I was afraid to leave it on long figuring I might stress
    eg> the conditon. I called a repair technician and he came over today.

    eg> The repair technician went into the service mode of the TV and changed
    eg> a number of parameters stored in the EPROM and finally got it looking
    eg> as good a new. He also used an external alignment generator and the
    eg> grid looked straight and proper. Colors were true and bright. As I
    eg> said, this lasted about a couple of hours after he left and then the
    eg> screen went black (non of the projection tubes are generating any
    eg> output) which is exactly the condition that happened when the problem
    eg> first started. The filaments in the projection tubes glow and the
    eg> sound and power-on sequence is just as it should be. So far I have
    eg> not been able to get any type of picture back. I tried to get into a
    eg> service mode per the instructions to push the menu power and +vol
    eg> button. I have no picture and that did not give me one to be able to
    eg> see any setup procedure. Again, would a bad EPROM result in NO
    eg> output from the projection tubes?


    eg> Anyone have any ideas where to start?


    Could be the tuner shield ground problem where the solder cracks along
    the edge of the PCB. This has many different symptoms. Some people
    were being waken in the middle of the night with the TV blasting at
    full volume on a blank channel. Some had the sound muted permanently.
    For some the tv would turn itself off. They thought their tv was
    possessed. Others had the HOT fail repeatedly. Still others had a
    corrupted eprom. There is a FAQ for the GE/RCA/Thompson bad tuner
    shield ground problem. Good luck.

    A*s*i*m*o*v

    .... This message transmitted on 100% recycled photons.
    Asimov, Jan 4, 2006
    #2
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  3. Kev Guest

    Try Replacing RN14501 in frame section.
    Kev, Jan 4, 2006
    #3
  4. John-Del Guest

    Sounds like a coolant leak. Look at the front of the signal board for
    any clear liquid. I had several that caused intermittent picture.

    John
    John-Del, Jan 4, 2006
    #4
  5. I'd be looking for a coolant leak. About half of the problems that we have
    seen on the 195 chassis have been related to coolant on the boards. It can
    be hard to find but the first thing to look for is a dark goo on top of the
    board.

    Leonard

    <> wrote in message
    news:...
    > This is a continuing saga of a 60 inch rear projection RCA TV. It has
    > a chassis number of
    > PTK195AC and is model P60812BL. I have now had a repair technician
    > over and it worked like a charm while he was here and for a couple of
    > hours after he left. Then it returned to the absolutely black picture
    > it had when the problem first surfaced a few days ago. The repair
    > technician feels he should change the EPROM. Can an EPROM problem
    > result in NO output from a projection tube?
    >
    > This is the sequence of events.
    >
    > The other day one minute it was working perfectly (as it has for 8
    > years). All of a sudden I walked into the room and the screen is black
    > (none of the projection tubes are putting out any light).
    > Turning it off, using the DVD and many other attempts to get a picture
    > failed. I let it stay off for a while, then turned it on. It would have
    > a
    > picture for a short time that looked like an old 60's horizontal hold
    > problem with a partial, shrunken picture. After a while the picture
    > would be stable enough to be able to read letters, but totally
    > distorted. I was afraid to leave it on long figuring I might stress
    > the conditon. I called a repair technician and he came over today.
    >
    > The repair technician went into the service mode of the TV and changed
    > a number of parameters stored in the EPROM and finally got it looking
    > as good a new. He also used an external alignment generator and the
    > grid looked straight and proper. Colors were true and bright. As I
    > said, this lasted about a couple of hours after he left and then the
    > screen went black (non of the projection tubes are generating any
    > output) which is exactly the condition that happened when the problem
    > first started. The filaments in the projection tubes glow and the
    > sound and power-on sequence is just as it should be. So far I have
    > not been able to get any type of picture back. I tried to get into a
    > service mode per the instructions to push the menu power and +vol
    > button. I have no picture and that did not give me one to be able to
    > see any setup procedure. Again, would a bad EPROM result in NO output
    > from the projection tubes?
    >
    >
    > Anyone have any ideas where to start?
    >
    Leonard Caillouet, Jan 4, 2006
    #5
  6. Also look around the red connector at the front of the board on the right.

    Leonard

    "John-Del" <> wrote in message
    news:...
    > Sounds like a coolant leak. Look at the front of the signal board for
    > any clear liquid. I had several that caused intermittent picture.
    >
    > John
    >
    Leonard Caillouet, Jan 4, 2006
    #6
  7. Guest

    Well, I thought you-all were pulling my leg about coolant. What is the
    origin of this coolant? I looked around on top of the boards (and my
    service repair guy also had the chassis out and did not mention
    coolant--but I will ask him about that) and I see only a light dust
    over the surface of the boards (chassis is quite clean for something
    not touched in 8 years). Since I have the service manual, could you
    give me a number/letter coordinate to locate this possible leak? The
    boards are labeled Main Circuit Board, Convergence Circuit Board, etc.


    I hear your suggestions, but since the repair technician is headed
    toward replacing the EPROM, I would like your evaluation as to whether
    that makes sense or not. By the way, apparently there are TWO EPROMS
    from what I am reading in the service manual.
    , Jan 4, 2006
    #7
  8. Guest

    John-Del wrote:
    > Sounds like a coolant leak. Look at the front of the signal board for
    > any clear liquid. I had several that caused intermittent picture.
    >
    > John


    I agree, it really sounds like a simple case of crt coolant leaking
    somewhere on a circuit board. Trying to tell someone a specific
    location to look is not going to help as the coolant could be anywhere.
    It will take a good visual inspection of the boards.

    A second possibility is some glue under a surface mount capacitor could
    have gone conductive on the clock or data lines. Another hard one to
    find for someone who has not had to sit and troubleshoot the light box
    for weeks in the shop.

    An eeprom is 99% sure not the problems here.

    David
    , Jan 4, 2006
    #8
  9. James Sweet Guest

    wrote:
    > Well, I thought you-all were pulling my leg about coolant. What is the
    > origin of this coolant? I looked around on top of the boards (and my
    > service repair guy also had the chassis out and did not mention
    > coolant--but I will ask him about that) and I see only a light dust
    > over the surface of the boards (chassis is quite clean for something
    > not touched in 8 years). Since I have the service manual, could you
    > give me a number/letter coordinate to locate this possible leak? The
    > boards are labeled Main Circuit Board, Convergence Circuit Board, etc.
    >
    >


    The coolant is glycol based and is used between the face of the
    projection CRTs and the optics. It conducts heat away from the tubes to
    a heatsink around the rim where the lense assembly bolts on. Very old
    projection sets were air cooled, but just about anything made in the
    last 20 years will be liquid cooled.
    James Sweet, Jan 5, 2006
    #9
  10. Guest

    I looked very carefully in the area below the CRT to optic interface
    and then all over the boards. I also ran my finger under and around
    the plastic cover area over the projection tubes where I would think
    there would be residue if there was a leak. I then looked over both
    the main boards. I sure don't think there is a leak. The boards look
    very clean except a very slight dust due to the years of just sitting
    around.

    Again, do you think that the EPROM could cause a complete lack of the
    projection tubes putting out any light? The only evidence that the TV
    is working is the regular starting sequence, normal sound and a glow of
    the filiments from the projection tubes.
    , Jan 5, 2006
    #10
  11. Guest


    > Again, do you think that the EPROM could cause a complete lack of the
    > projection tubes putting out any light? The only evidence that the TV
    > is working is the regular starting sequence, normal sound and a glow of
    > the filiments from the projection tubes.


    And again, 99% sure the EEprom is NOT the cause of the problem. The
    technician needs to take the light box into the shop where it can be
    properly troubleshot and repaired. If the tech still thinks it is the
    eeprom and wants to just throw parts at the set, I would suggest you
    ask if the servicer has a bench tech who can work on the set when the
    light box is taken in. I do hope the servicer was RCA authorized and
    attended all the factory training.

    The ctc195 series is a PIA to troubleshoot and it is prone to lots of
    intermittent issues. There are also multiple service bulletins that
    need to be checked for the specific set to see what serial number range
    it falls under.

    99% of the time an eeprom looking problem on that chassis winds up
    being glue that has become conductive underneath a surface mount
    component on the clock or data lines. I have repaired several hundred
    of that chassis with this very specific problem over the last 6 or so
    years.
    , Jan 5, 2006
    #11
  12. Guest

    Ohhh boy. I hope the technician is right and we are wrong. Just for
    reference, the Service # is P60812BLLG2. The number on the metal tag
    on the main board is CTC195A JR47344C9D. The # on the digital
    convergence board is PTK195AC 0 7355K2D
    A number below that (which looks like a serial number) is
    59835735521092RWB-TCE.

    The technician said that the service number was the important number
    for ordering the EPROM.

    Which of these numbers have significance to any of you?
    , Jan 5, 2006
    #12
  13. kip Guest

    Its not an EPROM problem...
    Get somebody in that has chipper checker and get IT tested.


    <> wrote in message
    news:...
    > Ohhh boy. I hope the technician is right and we are wrong. Just for
    > reference, the Service # is P60812BLLG2. The number on the metal tag
    > on the main board is CTC195A JR47344C9D. The # on the digital
    > convergence board is PTK195AC 0 7355K2D
    > A number below that (which looks like a serial number) is
    > 59835735521092RWB-TCE.
    >
    > The technician said that the service number was the important number
    > for ordering the EPROM.
    >
    > Which of these numbers have significance to any of you?
    >
    kip, Jan 6, 2006
    #13
  14. Guest

    The so called technician hasn't a clue and is guessing. You need to
    call someone out while the set is non-functional to hook up the
    computer interface and read any error codes and ping the data bus
    connected devices in the set.

    Or, you can waste your time and money having the same technician keep
    guessing on your set until it is beyond economical repair.
    , Jan 6, 2006
    #14
  15. Guest

    Last night I turned on the TV --still no output from projection tubes
    -- and rapidly pluged in the AC plug and disconnected it. Don't ask me
    why I did it, I guess I thought I might simulate the original cause?
    Anyway, the projection tubes "flashed" on for a split second, so it
    looks like they are just "turned off" somehow. The technician told me
    that the projection picture tube filiments are powered from the
    horizontal circuit, so that circuit must be working since the filiments
    are glowing.

    We are still waiting for the EPROM to come in. I have mentioned the
    things you-all have talked about, and he does not discount them, so
    that is good. His rationail that the EPROM is the problem is that it
    was corrupted when he first looked at it. It is in the state it was
    when the original problem occurred before it "kind of" came out of it
    and present enough of a picture that he was able to see enough of the
    picture to get it working normally.

    Is there a major problem in changing the EPROM and that NOT being the
    primary problem? Would that create a larger problem in getting the
    parameters back? Does he have to somehow download the old EPROM
    parameters into the new EPROM? Does the new EPROM come loaded with
    some "default" parameters so the TV is able to provide a picture if the
    EPROM is the problem?

    Can and should he bring out the chipper checker when he comes?
    , Jan 7, 2006
    #15
  16. Guest

    I started another thread since I thought this would continue. In it I
    wrote

    Today the technician came and changed the EPROM and as you-all pretty
    well told me, it was not the EPROM. After I mentioned the coolent
    problem, he homed in on that and found a couple of drops and after that

    pretty well gave up saying that the board was as good as gone. Since
    now the TV is so much garbage unless I find an answer to this, I tore
    into it tonight.

    Well, to make a long story short, what I did fixed it (at least for
    now). You can read about the details below:

    Yes, there is a drop or two (and a drop or 2 is not
    an exaggeration). There is a drop or two on a wire and some evidence
    in of it (a slight film on the top surface of the components) in the
    vertical deflection section on the right rear side of the main board).
    There is NO evidence that any corrosion has started anywhere I can see
    on the main board. I took the main board out of the plastic tray and
    examined both sides with high power magnifiers and the circuitry looks
    clean and bright.


    Very interesting finding, however. The large chip behind the tuner
    (UT16201) was soldered in by someone and there is a lot of solder flux
    around the chip. It appears that their was some circuit damage when it

    was replaced. Now, I have never had a repair person in to look at the
    TV, so this must have happened at the factory (TV bought in June of
    1998).


    Anyway, I am cleaning the underside of the board carefully with some
    circuit board cleaner in the area of the UT16201, the EPROM and the
    vertical deflection section as well as the Micro (U13101) in the rear
    of the main circuit board. I assume that the possibility of conductive

    glue mentioned around the clock and data lines described in the
    previous postings would be in this area (described as the service micro

    on the board).


    I will now reassemble the TV and try it out. If what I have done does
    not demonstrate improvement, do you-all think it wise to remove the
    chassis and find a knowledgeable repair person to look at it? How do I

    find THAT person? This outfit I used was listed as a factory
    authorized repair service.


    Again, for reference, the service # is P60812BLLG2. The number on the
    metal tag
    on the main board is CTC195A JR47344C9D. The # on the digital
    convergence board is PTK195AC 0 7355K2D
    A number below that (which looks like a serial number) is
    59835735521092RWB-TCE.


    Thanks again everyone for your comments and suggestions.
    , Jan 10, 2006
    #16
  17. Guest

    Its now nearly a month later and my RCA 60" TV is still working. The
    picture is great. I think the convergence could use some improvement
    in the lower left corner, but not having a color/bar/dot generator and
    not wanting to push my luck, I am very happy with it right now. The
    technician sent me $150 of the $250 back and so I guess I learned some
    things and hopefully have a working TV for a few years until I have to
    go to HDTV.
    , Feb 3, 2006
    #17
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