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  • C64/C128 changing TV channel as it gets warm

    From Christian Johansson@c64@combort.se to comp.sys.cbm on Friday, July 11, 2003 20:15:30
    From Newsgroup: comp.sys.cbm

    Hi!

    In 1986 I got a C64, which I had connected to a TV set. The C64 later broke down and I got a new one on the warranty. Last year, I bought an old C128, which I also connected to a TV set. These computers all have in common that
    as the computer heats up after it has been turned on, the channel that it transmits on increases until after a while it stabilizes somewhere between channel 36 and 37. It seems to be different from computer to computer how
    much the channel increases until it stabilizes. Some computers change
    channels so much so that if you let the TV stay at the original channel,
    after a while you can't read the text on the screen and only hear noise. I
    find it a bit annoying that I have to fine tune the TV channel on the TV set until the computer has become heated up and the channel has stabilized. This problem has occurred with several different TV sets so it is not a problem
    with the TV set. It has also occurred with all C64/C128 computers I have
    tested with so it seems like it is a general problem. However, when I in the 80s mentioned this problem to other C64 users, they didn't recognize the problem. I find this very strange since I have had it with all my C64s/C128s (except for my newest C128 since I have only had that connected to a monitor
    so I don't know if the problem occurs when connecting it to a TV set). Is
    this really a general problem or have I only had extremely bad luck with all
    my C64s/C128s (the latter seems pretty improbable I think)?

    /Christian (change "combort" to "comhem" in my e-mail address if responding
    via e-mail)


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  • From Peter van Merkerk@merkerk@deadspam.com to comp.sys.cbm on Saturday, July 12, 2003 01:06:20
    From Newsgroup: comp.sys.cbm

    In 1986 I got a C64, which I had connected to a TV set. The C64 later
    broke
    down and I got a new one on the warranty. Last year, I bought an old C128, which I also connected to a TV set. These computers all have in common
    that
    as the computer heats up after it has been turned on, the channel that it transmits on increases until after a while it stabilizes somewhere between channel 36 and 37. It seems to be different from computer to computer how much the channel increases until it stabilizes. Some computers change channels so much so that if you let the TV stay at the original channel, after a while you can't read the text on the screen and only hear noise. I find it a bit annoying that I have to fine tune the TV channel on the TV
    set
    until the computer has become heated up and the channel has stabilized.
    This
    problem has occurred with several different TV sets so it is not a problem with the TV set. It has also occurred with all C64/C128 computers I have tested with so it seems like it is a general problem. However, when I in
    the
    80s mentioned this problem to other C64 users, they didn't recognize the problem. I find this very strange since I have had it with all my
    C64s/C128s
    (except for my newest C128 since I have only had that connected to a
    monitor
    so I don't know if the problem occurs when connecting it to a TV set). Is this really a general problem or have I only had extremely bad luck with
    all
    my C64s/C128s (the latter seems pretty improbable I think)?

    The problem is caused by the cheap RF modulator used inside the C64/C128.
    It's design doesn't make any attempt to keep the output frequency constant.

    I can think of a couple of explanations why other C64 users didn't
    experience the problems your described:
    1. They used the video output instead of the RF modulator (which gives a
    better picture quality as well);
    2. They used a TV set with a (better) AFC feature, which keeps the set automatically tuned even when the output frequency of the RF modulator (slightly) drifts;
    3. They kept their C64 running 24/7;
    4. I read somewhere that early C64 models used a better RF modulator.


    --
    Peter van Merkerk
    peter.van.merkerk(at)dse.nl


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  • From Steppe@steppe_not_for@spam_demodungeon.com to comp.sys.cbm on Saturday, July 12, 2003 01:24:35
    From Newsgroup: comp.sys.cbm

    Christian Johansson wrote:
    These computers all
    have in common that as the computer heats up after it has been turned
    on, the channel that it transmits on increases until after a while it stabilizes somewhere between channel 36 and 37.

    That's very strange, I never had this problem, not even slightly. And from
    1986 to 2003 I used about 8 different C64s, none of them showed that
    behaviour.

    /Steppe


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  • From Christian Johansson@c64@combort.se to comp.sys.cbm on Sunday, July 13, 2003 11:33:19
    From Newsgroup: comp.sys.cbm

    Thank you for your response.

    1. No, they used the RF output.

    2. No, I don't think this is the explanation either. I have had the same problem with three TV sets: one from 1973, one from 1985 and one from 2001.
    The one from 2001 should at least have a good AFC feature I think.

    3. No, they didn't keep their C64s running all the time so this is not the explanation either.

    4. Almost all my friends had an old "breadbin" C64 while I have only used
    C64C and C128 so this could possibly be at least a part of the explanation.

    /Christian


    "Peter van Merkerk" <merkerk@deadspam.com> skrev i meddelandet news:benfuc$76h1e$1@ID-133164.news.uni-berlin.de...
    In 1986 I got a C64, which I had connected to a TV set. The C64 later
    broke
    down and I got a new one on the warranty. Last year, I bought an old
    C128,
    which I also connected to a TV set. These computers all have in common
    that
    as the computer heats up after it has been turned on, the channel that
    it
    transmits on increases until after a while it stabilizes somewhere
    between
    channel 36 and 37. It seems to be different from computer to computer
    how
    much the channel increases until it stabilizes. Some computers change channels so much so that if you let the TV stay at the original channel, after a while you can't read the text on the screen and only hear noise.
    I
    find it a bit annoying that I have to fine tune the TV channel on the TV
    set
    until the computer has become heated up and the channel has stabilized.
    This
    problem has occurred with several different TV sets so it is not a
    problem
    with the TV set. It has also occurred with all C64/C128 computers I have tested with so it seems like it is a general problem. However, when I in
    the
    80s mentioned this problem to other C64 users, they didn't recognize the problem. I find this very strange since I have had it with all my
    C64s/C128s
    (except for my newest C128 since I have only had that connected to a
    monitor
    so I don't know if the problem occurs when connecting it to a TV set).
    Is
    this really a general problem or have I only had extremely bad luck with
    all
    my C64s/C128s (the latter seems pretty improbable I think)?

    The problem is caused by the cheap RF modulator used inside the C64/C128. It's design doesn't make any attempt to keep the output frequency
    constant.

    I can think of a couple of explanations why other C64 users didn't
    experience the problems your described:
    1. They used the video output instead of the RF modulator (which gives a better picture quality as well);
    2. They used a TV set with a (better) AFC feature, which keeps the set automatically tuned even when the output frequency of the RF modulator (slightly) drifts;
    3. They kept their C64 running 24/7;
    4. I read somewhere that early C64 models used a better RF modulator.


    --
    Peter van Merkerk
    peter.van.merkerk(at)dse.nl




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