Re: identical G05-802 problem with 2 different deflection PCBs

Yes, I checked the chassis. Even at multiple stages, with and without
the screws etc.

Colin

On 30 Nov 2009, at 14:09, COLIN DAVIES wrote:

> I know you said you checked for shorts on the looms.... but I saw no
> mention of the chassis... So....
> Are any of the Chassis Transistors (body or leads) shorted to the
> chassis iself ?... ( The Screws should be insulated and you need to
> use a mica insualtor if it were misssing... That would be sure to
> cause trouble....
>
> Regards, Colin Davies
>
>
> --- On Mon, 30/11/09, Colin O'Brien <colin@onepointzero.com> wrote:
>
> From: Colin O'Brien <colin@onepointzero.com>
> Subject: Re: VECTOR: identical G05-802 problem with 2 different
> deflection PCBs
> To: vectorlist@vectorlist.org
> Date: Monday, 30 November, 2009, 11:42
>
>
> I did in the beginning, but since then I've only re-metered the
> sections that connect directly to the deflection PCB side without
> finding anything.
> I'll give it another thorough going through just to be sure.
>
> Colin
>
>
>
> On 30 Nov 2009, at 11:06, Pinx wrote:
>
> > Have you meter'd all your looms for dead shorts ?
> >
> > Pinx
> > ----- Original Message ----- From: "Colin O'Brien" <colin@onepointzero.com
> >
> > To: <vectorlist@vectorlist.org>
> > Sent: Sunday, November 29, 2009 11:18 PM
> > Subject: VECTOR: identical G05-802 problem with 2 different
> deflection PCBs
> >
> >
> >>
> >> Hello,
> >>
> >> I've been a lurker here for a while, quietly absorbing the
> insight but I've hit a problem that has me (and my limited
> knowledge) baffled.
> >>
> >> I have a working asteroids game board (2 actually), with which I
> can play fine on the scope (also when grabbing the signal from
> P100 instead of the test points)
> >>
> >> When I initially got the machine, I had problems with the monitor
> (G05-802) having no horizontal deflection and the spot killer being
> active. After checking the PCB, I replaced a couple of transistors
> on the board a well as the Q708 & 709 chassis transistors.
> >>
> >> Upon powering up, I would lose the 2 chassis transistors in
> question and sometimes the F700 fuse. I practically inspected every
> single component on the board, but found no extra faults. I looked
> for shorts, tested voltages (95V at P500, 30-35 VAC coming in at
> P100 pins 7 & 10, 12kV for HV etc) but found nothing that looked
> suspicious to me.
> >>
> >> I recently got a new known working/tested deflection PCB as a
> comparison/reference point, hoping that would help me see what was
> wrong or, at the worst, serve as a working board. Well, no luck
> there, when I plugged it in the spot killer was on and I had no
> horizontal deflection. I guess I can deduce from this that my
> problem is outside the PCB itself?
> >>
> >> Powering it up a second time to take some readings, the spot
> killer was still on but I'd lost the picture, turning brightness/
> contrast up only produced a faint haze towards the top of the screen.
> >>
> >> Inspection of the PCB revealed R713 was burnt to a crisp as well
> as its neighbours Q705 and Q706 both being shorted. I checked the
> chassis transistors, they were fine, I looked for shorts in the
> sockets, plugs and cables leading to them but found nothing wrong
> either.
> >>
> >> I replaced the dead components but powering it up now blows F700
> when I'm lucky or the chassis transistors. I'm weary of powering it
> up again as I don't feel like destroying components for the fun of
> it.
> >>
> >> I'm at a loss now, not sure where to look outside the PCB. Could
> the yoke be at fault? I'm in unknown territory here and would
> appreciate any pointers I can get.
> >>
> >> Thanks!
> >> Colin
> >>
> >>
> >>
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> >
> >
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Received on Mon Nov 30 09:28:09 2009