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

Check for wrong Transistors or transistors in the wrong socket.

Did you check to make sure
Q708 = 2N3716 - NPN
Q709 = 2N3792 - PNP
Don't forget to check for collector-->emitter shorts

Also check R720 and R721

Tim

-----Original Message-----
>From: Colin O'Brien <colin@onepointzero.com>
>Sent: Nov 30, 2009 2:28 PM
>To: vectorlist@vectorlist.org
>Subject: Re: VECTOR: 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
>> >>
>> >>
>> >>
>> ---------------------------------------------------------------------------
>> >> ** Unsubscribe, subscribe, or view the archives at http://www.vectorlist.org
>> >> ** Please direct other questions, comments, or problems to chris@westnet.com
>> >
>> >
>> ---------------------------------------------------------------------------
>> > ** Unsubscribe, subscribe, or view the archives at http://www.vectorlist.org
>> > ** Please direct other questions, comments, or problems to chris@westnet.com
>>
>> ---------------------------------------------------------------------------
>> ** Unsubscribe, subscribe, or view the archives at http://www.vectorlist.org
>> ** Please direct other questions, comments, or problems to chris@westnet.com
>
>---------------------------------------------------------------------------
>** Unsubscribe, subscribe, or view the archives at http://www.vectorlist.org
>** Please direct other questions, comments, or problems to chris@westnet.com

---------------------------------------------------------------------------
** Unsubscribe, subscribe, or view the archives at http://www.vectorlist.org
** Please direct other questions, comments, or problems to chris@westnet.com
Received on Mon Nov 30 20:12:40 2009