Re: Amplifone monitor - still stumped on bright dot in middle.

Hey John, I am by no means a guru here, but do you have access to a
rejuvinator? They can tell you a few things about the condition of the tube.
Shorts being one of them.

Jordan B

On Sun, Jul 24, 2011 at 8:38 PM, John Huie <jehuie@sbcglobal.net> wrote:

> John said, "I suspect that signal is your problem though. Either it is not
> coming from the board or it is not amplified by the monitor chassis or
> possibly the picture tube has a cathode short and this negates the Z-axis
> level completely. Not sure about that last hypothesis though..."
>
> Thank you John. I'm focusing on that last part you said now because it
> makes sense to me. I'm thinking that you mean if I measure the voltages on
> either of the 3 color signals from the SW CPU board that will indicated my Z
> signal, correct? Which is why I really need a scope.
>
> However, since both my SW boards do the same thing and work fine in my
> other SW game, they are clearly generating the Z signal. Which leaves the
> other two options.
>
> It seems unlikely that all 3 colors would be having problems amplifying by
> the monitor chassis. And since the dot in the middle is pure white, I think
> we can negate that possibility. I'm not sure this is true but I'm not
> getting a lot of feedback so that's my best guess.
>
> So that leaves me with a short in the monitor as being my most likely
> culprit. I tested for a short at the pins and only found a short going from
> the heater pins to pin 4. I'm still not sure if that is ok or not though.
> And if it's a problem, whether there is a work around or if it means I'm
> screwed and need a new tube.
>
> Help. Pretty please!
>
>
>
> --- On *Sat, 7/23/11, John Robertson <pinball@telus.net>* wrote:
>
>
> From: John Robertson <pinball@telus.net>
> Subject: Re: VECTOR: Amplifone monitor - still stumped on bright dot in
> middle.
> To: vectorlist@vectorlist.org
> Date: Saturday, July 23, 2011, 7:51 PM
>
> John Huie wrote:
>
> Just to refresh...this monitor on this Star Wars works good and the
> graphics are all there and everything but there's a constant bright dot in
> the middle. If I turn the brightness down enough for the dot to go away
> then I can't see the other graphics at all.
>
> Here's what I've tried so far:
>
> - Bought a whole slew of components from Bob Roberts to rebuild the
> deflection board and HV board
> - HV is good.
> - B+ is good.
> - Adjusting color drives doesn't help. Brightness down and the color
> drives up still won't let me turn down dot enough to see graphics well.
> - I don't have any spare parts to swap in. I only have 6100 vectors other
> than this.
> - double checked continuity from focus block wiring, all connections under
> boots are good. Good continuity back to HV board and color drives on
> deflection board are good.
> - Pins on neck not shorted to heater pins. (Except pin 4 which isn't used
> - could this be a problem?)
> - W jumpers are all long gone.
> - Resistors in neck board/ring are good.
> - Does same thing with known working PCB set.
> - Reflowed J103 and tested continuity along wires.
> - Ground to neck board/ring is good.
>
> Still not sure how to check Z signal. What components should I be looking
> at that are common to all 3 colors that could be causing this?
>
> Any other idea?
>
> Thanks everyone. I'm working on this for a friend of mine and just about at
> the end of my rope.
>
> Z-Signal is the brightness. What sort of test equipment do you have? A
> 'scope would be best - you could check that the signal is varying. An AC
> setting on your multimeter will give you an idea if there is change on that
> signal, but I do not know what the result should be for your meter or
> situation. If someone here has a voltmeter and can see what reading they get
> on the Z-level when the board is on a set screen test that would help you
> figure out if yours is working properly.
>
> I suspect that signal is your problem though. Either it is not coming from
> the board or it is not amplified by the monitor chassis or possibly the
> picture tube has a cathode short and this negates the Z-axis level
> completely. Not sure about that last hypothesis though...
>
> John :-#)#
>
> --
> John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
> Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames)
> www.flippers.com
> "Old pinballers never die, they just flip out"
>
>

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Received on Sun Jul 24 23:44:23 2011