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CTC195 woes

Discussion in 'Electronic Repair' started by [email protected], Mar 7, 2007.

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    Yes, the dreaded JURB is back with another one.

    P46924, PTK195M chassis.

    Been through the training manual and everything on this one.

    Need to know first of all if one of my assumptions are correct. I went
    trough the "no relay click dead set" part.

    It says to look for 7.6V feeding the jungle IC. It doesn't mention
    anything about condition of the set, i.e. off or on. What I saw is
    that the 7.6 was only up in the on mode, that is when pin 19 of the T4
    is high.

    Upon AC power up it did come up momentarily and at that time there is
    clock and data at the jungle IC (43-44) I think. The EPROM, T4 and the
    jungle have all been replaced resulting in no change.

    The EPROM has been changed back to the original. Our guy with the
    chipper checker got there the next day. First of all it wouldn't ID
    the chassis. When the chassis was manually entered it found about
    twenty entries in the EPROM that are not default. Those were
    corrected.

    Now pin 19 of the T4 is high automatically, the 7.6V is always there
    and there is always data and clock at the jungle IC. This seems like
    the on state.

    So have I moved forward or backward here ? Was the handshake succesful
    before and that allowed the 7.6V to shut off ? And now it keeps trying
    for the jungle IC. That did not happen when the jungle IC was changed,
    it happened when those default values were restored. Data and clock do
    quiet down after a few seconds, but is constant at the jungle IC now.

    So I do have the correct new EPROM for the set, so I believe that the
    other conditions will be restored once that is reinstalled. I decided
    to let him restore those values because I believe it best to stick
    with the original EPROM to avoid aligning the thing.

    I'm running the job, but I don't have alot of experiene with the
    chipper checker. But t this point, if I have gone backwards, is there
    a way with the software to just get the default values fron the new
    EPROM and load them and them only into the original EPROM ?

    Of course that is after the thing works. It still won't fire up.

    Chipper check says it cannot communicate with the T4, but obviously it
    is finding the EPROM. It had three code 16s in it also, but everything
    I see digital is fine, pulses are at the rails. Nothing is less than
    full amplitude. Keyboard scan is fine, and of course I unplugged it
    anyway.

    Now about the code 16, I have seen alot of 195s that had that error
    code, but in almost every case I saw it, like after a flyback
    replacement or some other routine thing like that.

    Perhaps this is a real one ? And it's somewhere else ? But does that
    throw a code 16 ? Bus locked at zero, could that be possibly around,
    for example, the audio control IC ? It is bus controlled.

    Do I have to look at everything ? and then there's the gemstar, which
    has been swapped out. That I consider inconclusive because it was out
    of a 195D which uses a different T4 and EPROM. It was extremely
    similar, and did not change anything. The original was plugged back in
    and again it did not change anything. I looked at the data at startup
    and it looked the same, the timing ouf it and all.

    BTW, they say use 10uS to view it, no, crank it down to 1mS or
    something. You can't read all those pulses without a logic analyser
    anyway, but seeing the big picture that way lets you see the structure
    of it. I saw the structure change when certain things were done. I
    prefer 1 or 20 mS. I doubt I would see it any better at 10uS, in fact
    it would be worse, I know, I did it.

    Chipper can't communicate with the T4, but finds the EPROM. See now I
    tend toward the problem is local. Chipper check should be able to ID
    the chassis, but can not. In it's previous state It got up, talked to
    the jungle IC and whatever else and then went off mode. Why would the
    T4 go through the sequence of initializing the peripherals and then go
    deaf, dumb and blind ?

    Will it throw a code 16 if it fails to get data from a peripheral ?
    They are usually isolated by 100 ohm resistors.

    This is not three strikes, it is no strikes. No balls, no pitches.

    Don't beat your head on the wall too hard, but anything on this one
    would be great. If you beat your head on the wall and tip me off on
    this I would send you ABCs, which is aspirin, beer and condoms. Or
    whatever.

    JURB
     
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