Re: Speaking of Vectorbeam/Cinematronics...

Rodger Boots wrote:
>
> Banded end is cathode.
>

Details, details...

Opps!

Thanks,

John :-#)#
> On Jan 18, 2011 2:26 PM, "John Robertson" <pinball@telus.net
> <mailto:pinball@telus.net>> wrote:
> > John Huie wrote:
> >> I've sworn off working on this one but I'm curious what those "in the
> >> know" think.
> >>
> >> I've got a Cine monitor that works but is missing the vertical
> >> deflection. I tested the deflection transistors on the heat sinks and
> >> two of them were bad. Upon replacing them, it behaved exactly the
> >> same way but one of those previously bad transistors heats up veeery
> >> quickly. So hot that you don't want to touch it.
> >>
> >> If this were your monitor, what would you suspect as the cause for
> >> overheating one of those transistors? I've double checked to be sure
> >> it's not grounded out. I'm thinking the thing should just be sent off
> >> to someone who has more background than myself but it is interesting
> >> to me to hear your thoughts anyway.
> >>
> >> John
> >>
> > Hi John,
> >
> > Try my voltage checks that I have just posted earlier today (Tech
> Tips -
> > Vectorbeam...). Remember to unplug the yoke for doing these tests to
> > avoid damaging components.
> >
> > Do you understand what the Diode Test is? Rather simple - most modern
> > digital multimeters have a diode test built in. The switch position
> > shows a diode... The negative lead is often the anode (banded end of a
> > diode) and the positive lead is then the cathode (other end) - if you
> > put the meter leads across a good diode you should see something like
> > 0.3xx (Germanium ) to 0.8xx volts (Silicon diodes) when the leads are
> > one way and open when the leads are reversed.
> >
> > Power OFF!!
> >
> > Now if you take the leads and check a transistor you will find that if
> > the leads are across the Emitter and Collector of a transistor you
> > should have roughly 0.7xx V or higher (open is often the case - a meter
> > reading being blank or whatever the meter shows for not connected),
> > anything around 0.0xx is likely a shorted transistor. Now find the Base
> > of the transistor and put the leads between the Base and Collector
> > (reverse leads if no reading) - should be around 0.7xx V, and repeat
> for
> > the Base and Emitter (roughly the same 0.7xx voltage). Sometimes you
> > will have a lower reading and you may have to remove the transistor to
> > see if the rest of the circuit is causing anomalous readings (small
> > value resistor for example) - if it checks OK out of circuit then it is
> > /probably/ OK and can be put back.
> >
> > Check ALL transistors and diodes for shorts or weird readings - with
> > these monitors the readings should be similar between the two channels
> > (X &Y deflection) comparable transistor/diodes.
> >
> > Or you can send the chassis off to someone to fix - I'm sure there may
> > be someone close to you (I'm in Canada) that can help.
> >
> > 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 <http://www.flippers.com>
> > "Old pinballers never die, they just flip out"
> >

-- 
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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