Weird problem with WG 19K6100 monitor (LONG)

I have a weird problem with a XY monitor (WK19K6100).

HV P316
Defl P314
Neck P328 (on a little white sticker, yes I do have the purple wire to HV).

I have no history with this, it was DOA when I got it and appears to have
stumped the previous owner judging by the mess I had to clean up.

I've fixed some problems on the deflection pcb and installed an LV2000.
HV is 18.8KV, which seems pretty close.

In short, I have what I think is a neck board problem but it also affects the
operation of the game pcb which is really odd.

Nearly all the time all you see on the screen is a rainbow like image
indicating what looks like a lack of focus (unless you have focus cranked
way down in which case the screen is blank).

Additionally, upon first powering up, I hear a distinct buzzing/sparking
noise from the neck pcb -- I think from the tube socket, but it's hard to
tell.

This lasts for about 30 seconds, regardless of the setting of the screen
(brightness) or focus controls. Depending on the level of the brightness
control, you may start seeing vectors at this point, if you do, it'll soon
start sparking again.

With the brightness set lower, the sparking noise always stops completely
about 30 seconds after power-up.

I have taken a short MPEG of this:
http://www.tonyjones.com/games/tempestscreen.mpg

There is a fair bit of background noise (PC fans etc) but you can hear the
sparking, which stops for a couple of seconds towards the end, but then starts
again (because I have the brightness cranked up too high).

Interesting point is that whenever you hear the sparking noise, the spot
killer is on and the game pcb isn't running correctly (see solid player 1/2
LEDs in MPEG).

As soon as the sparking ends, the spot killer goes off and the player 1/2 LEDs
start flashing at the normal speed. At this point, the game plays fine blind.

At this point, if you crank up the brightness, the sparking noise starts again
(until you lower the brightness), spot killer lights and the player 1/2 LEDs
go solid, or flash very fast. One time upping the brightness level like this,
I blew F100 (I know a bad C503 can blow fuses).

http://www.tonyjones.com/games/tempestscreen2.mpg

In this one you can see vectors start to appear as the brightness is cranked
up and then towards the end, the spark noise starts (spot killer lights, game
board goes south -- player 1/2 LEDs will go solid if in attract, if playing a
game, start hearing weird sounds etc). I'm guessing the reason I'm seeing
vectors at times is because I have the brightness level high enough to
overcome the spot killer circuitry.

The pcb board is 100% rock solid (REALLY!!!), plays fine with the monitor
installed into the cabinet, though I'm reluctant to keep on running these
tests in case it ceases to be. I just plugged the game board back into the
working monitor in the cabinet and it's been running fine for over an hour.

I removed the back portion of the neck socket to expose the white wire.
With the neck board unplugged, you hear the spark noise forever (spot killer
lit, game board player 1/2 LEDs solid). I couldn't see any sparking on
either the white wire or at any of the neck pins.

Unsure how to remove the rest of the plastic casing around the neck socket
to fully expose the underneath of the neck pins, is it possible ? Didn't want
to break it.

Anyone have any troubleshooting tips?

- I was thinking of a) swapping a known good neck board into this chassis and
  b) installing this deflection board into a known working chassis, but
  havn't yet as I'd hate to damage known good equipment. How likely is this?

- I havn't played with any of the potentiometers on the neck board.

Tony

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Received on Sat Mar 15 13:07:34 2003