TECH: TZ clock motor board voltages? (repost)

Archived from groups: rec.games.pinball (More info?)

(I asked this here in April, but didn't get a single answer. Since I've
searched the Google groups with no luck, I'll repost this just this one
time)

After having one of the TZ clock optos changed the clock stopped working -
it won't run. I don't know if this was a consequence or just or coincidence,
but in the clock test nor during the game the clock won't run at all. The
optos register fine, so this time they shouldn't be the ones to blame.

While running the clock test, I measured the voltages from the "D.C. Motor
Control Assembly" (A-16120) and the J2 connector appeared to give only +-1-2
(fwd/rev slow) or +-3-4 (fwd/rev fast) VDC when it should, according to the
manual, give +20 VDC. The J1 connector seemed to receive about +13 VDC from
the power board, when it should get +12 - is this within acceptable limits?
Is it safe to assume that there's something wrong with this board? Any
guesses of which component is failing, if any?

What should I check next? My DMM skills are pretty much limited to voltage
measuring and continuity testing, so please be specific.

The picture of the board can be found in
http://www.marcospecialties.com/mmMS/Images/A-16120.jpg , the schematics of
the board (according to the manual) in
http://home.flipperit.net/jarkko/temp/tz_a-16120.png . The parts on the
A-16120 board are

1254: ----5 5768-13402-01 pcb-motor control 0
1255: ----5 5070-09054-00 diode-1N4004 1.0a 0
1256: ----5 5010-09061-00 res 680 1/2W 5% 0
1257: ----5 5010-10255-00 res 10 1/2W 5% 0
1258: ----5 5010-08997-00 res 2.7k 1/4w 5% 0
1259: ----5 5010-09085-00 res 1.5k 1/4w 5% 0
1260: ----5 5043-08980-00 cap 0.01m 50v +80-20 axial 0
1261: ----5 5043-08996-00 cap 0.1UF 50v +/-20 axial Z5U 0
1262: ----5 5043-12807-00 cap 1mfd 50v axial 0
1263: ---4 5791-12273-04 4h str sq lck .156 0
1264: ---4 5791-12273-05 5h str sq lk .156 0
1265: ---4 5671-13732-00 led dspl red 0
1266: ---4 5551-09822-00 ind 4.7 uh 3a 0
1267: ---4 5040-10974-00 cap 100M 35V radial 0
1268: ---4 5370-13342-00 ic 3a dmos bridge driver 0
1269: ---4 5490-10892-00 ic opto isolator 4N25 0
1270: ---4 5250-09157-00 reg 7805 1.0A 5V 0
1271: ---4 5281-09500-00 ic 74LS32 quad or 0

Thanks in advance,

--Jarkko
(please remove .nospamplease and .invalid if you reply by email)
7 answers Last reply
More about tech clock motor board voltages repost
  1. Archived from groups: rec.games.pinball (More info?)

    13V is within tolerances for the 12V supply

    There is no way that the circuit can deliver 20V from a 12V supply -
    the manual is incorrect.

    These motors are low voltage motors.Your voltages look low, but this is
    possibly because the clock speed is controlled by rapidly pulsing the
    motor. This will confuse meters.

    So I suspect that your clock is probably seized. Lubricant on the gears
    can do this. I would suggest removing the motor from the clock, you can
    do this without disassembling the clock, and see if the motor runs
    without the gear train connected. You can also check the resistance of
    the motor by measuring across pins 1 and 4 of J2 - expect a fairly low
    reading. If the reading is high, you have a motor problem.
  2. Archived from groups: rec.games.pinball (More info?)

    Yes, I was thinking about a different motor! You have to pretty much
    strip the clock to get to the screws so a cheap test motor is a good
    idea. The original gears will probably be OK once they are cleaned up.
    I did find that the new ones sit tighter on the shaft. If you do decide
    to replace all the gears (if they won't clean up or are broken, but
    youprobably don't need to) there's one gear that is used twice.
  3. Archived from groups: rec.games.pinball (More info?)

    The way the board works is the drive pin at J1 pins 1 and 2 on the
    board are driven low by a solenoid driver transistor on your driver
    board. When pin 1 is driven low by the driver board, the motor spins
    one way, when 2 is low it spins the opposite. This is an easy place to
    start measuring. Go into the appropriate solenoid test menu, into the
    solenoid tests, select the motor drive solenoids and make sure voltage
    is switching low during the test. If so, progress further into the
    A-16120 board.
    For a quick explanation of the way it works I'll just use pin 1 for an
    example. When the motor is told to run, voltage on pin 1 of J1 is
    driven low by the power driver board, when this happens voltage goes
    low on the output of the opto U1 pin 5, low on pin 7 of the L6203
    driver IC, then low on pin 3 output to motor, the other pin is at 12v
    so the motor turns one direction. If the motor needs to turn the other
    dirrection then instead of pin1 on J1 being driven low, the machine
    drives pin 2 low then the same exact thing happens on the A16120 board
    with the other opto, and opposite pins on the IC.
    Basically the outputs on pins 1 and 3 of the L6203 driver follow the
    inputs so if both inputs at pins 5 and 7 are high both outputs are high
    at 12v, so no motor rotation, when one input goes low, it's
    corresponding output goes low, so motor turns one dirrection. When the
    opposite input pin is driven low, the opposite output is driven low so
    the motor turns the other dirrection. There is also the enable pin at
    pin 11 of the IC, which needs to be high for the IC chip to function.
    That's it in a nutshell. Maybe a little technical, but everything is
    easily checked with a meter. Same exact board is used on NGG and mine
    quit so I got a little unwanted experience with it. Look closely at the
    2 coils L1 and L2, of of mine broke one lead flush with the board, not
    visible at first glance.
  4. Archived from groups: rec.games.pinball (More info?)

    My clock gears were siezed when I got my clock. You should be able to turn
    the gears by hand. Mine were locked up.

    The manual is your friend here. Spend a little time with the clock assembly
    diagram and text and become familiar with how it is put together.

    I had to totally disassemble and very lightly file the hubs of the gears.
    Careful here because you don't want to take too much off--take off just
    enough so they turn freely by hand. There are also some of the gears
    available new at the usual suspects. Also be careful not to lose the axles
    that the gears turn on. I did not use any lube when reassembling and my
    clock has worked perfectly for about 18 months.

    Thanks to Joel at Pinliz for helping me troubleshoot this as his boards at
    the time had not solved the problem. He also helped me get the gears back
    together. The manual is very specific on how they go back in. You have to
    find the small index marks on the gears. It's all in the manual.

    Hth.

    Otto

    CARGPB11

    My web page: http://home.bellsouth.net/p/PWP-Ottoslanding

    "martin" <martin.reynolds@gmail.com> wrote in message
    news:1119858805.173525.105750@g43g2000cwa.googlegroups.com...
    > So I suspect that your clock is probably seized. Lubricant on the gears
    > can do this. I would suggest removing the motor from the clock, you can
    > do this without disassembling the clock, and see if the motor runs
    > without the gear train connected. You can also check the resistance of
    > the motor by measuring across pins 1 and 4 of J2 - expect a fairly low
    > reading. If the reading is high, you have a motor problem.
    >
  5. Archived from groups: rec.games.pinball (More info?)

    Martin has a good suggestion about removing the motor from the clock to see if
    it runs. However, you'll have to remove the back panel from the clock and a
    few gears in order to reach the mounting screws for the motor. An easier test
    is to grab one of the 12 volt motors that Radio Shack sells for a couple of
    bucks and connect that to the output of the motor control board using a couple
    of jumper wires. You can find a motor that's very close to the original size
    (check Google for Mike Saunder's Indiana Jones owners page - he lists an RS
    motor that folks have used as a replacement for the Path of Adventure).

    Joseph "Tony" Dziedzic

    In article <1119858805.173525.105750@g43g2000cwa.googlegroups.com>, "martin"
    <martin.reynolds@gmail.com> wrote:
    >13V is within tolerances for the 12V supply
    >
    >There is no way that the circuit can deliver 20V from a 12V supply -
    >the manual is incorrect.
    >
    >These motors are low voltage motors.Your voltages look low, but this is
    >possibly because the clock speed is controlled by rapidly pulsing the
    >motor. This will confuse meters.
    >
    >So I suspect that your clock is probably seized. Lubricant on the gears
    >can do this. I would suggest removing the motor from the clock, you can
    >do this without disassembling the clock, and see if the motor runs
    >without the gear train connected. You can also check the resistance of
    >the motor by measuring across pins 1 and 4 of J2 - expect a fairly low
    >reading. If the reading is high, you have a motor problem.
    >
  6. Archived from groups: rec.games.pinball (More info?)

    Try a light bulb instead of a motor - a 44 or a 555. If the bulb
    lights, the motor should go.

    If the bulb does not light, it may be that one of the outputs is bad
    (the broken choke wire, for example). You can test this by connecting
    one side of the bulb to ground, and connecting the other side of the
    bulb to the motor leads and running the motor in both directions. of
    the four permutations, two should light the bulb.
  7. Archived from groups: rec.games.pinball (More info?)

    RonKZ650 wrote:
    > The way the board works is the drive pin at J1 pins 1 and 2 on the
    > board are driven low by a solenoid driver transistor on your driver
    > board. When pin 1 is driven low by the driver board, the motor spins
    > one way, when 2 is low it spins the opposite.

    Thanks, guys, for your answers so far.

    I did some additional measuring and the clock test drives J2 (not J1,
    which is the one getting voltage from the Power Driver Board) pin 1 or
    pin 4, depending on the direction, with appr. +-1-2 (slow) or +-3-4
    (fast) volts. This is normal, as RonKZ650 explained. I measured the
    volts in the wires that were disconnected from the clock motor base.

    However, with wires reconnected, the motor poles both (!) give the same
    voltages for one direction and zero voltage for the other. Does this
    indicate that the motor is 'shorting' or something, or is this just
    normal behaviour? I'll see if I can find another motor for testing
    purposes, as suggested.

    I don't think the clock gears are seized. The clock motor used to work
    without any problems, and I'm recalling it did run for a short while
    even after the latest disassembly/assembly.

    --Jarkko
    (please remove .nospamplease and .invalid if you reply by email)
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