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

So, I finally got through the whole cab checking for shorts and didn't
find anything suspicious as far as I could see.

This is where it gets interesting, after plugging everything back in,
I no longer have the spot killer on and I get a picture on the screen.
So, I'm guessing I "fixed" a bad connection this way. Which also means
it might re-appear.

However, if I leave it on for a minute or so, the brightness starts
varying/pulsing and the center beam dot appears along with the
increase, this gradually and randomly increases until I get retrace
lines which finally stay on. The contrast and brightness pots have
less and less effect until it reaches full strength and they have no
effect at all. This happens with the 2 different deflection PCBs and
the spot killer never turns on.

I measured voltage at Z on P100 over a few minutes but saw no gradual
increase.

Any idea on my new problem? :)

Thanks again,
Colin

On 01 Dec 2009, at 09:46, Colin O'Brien wrote:

>
> Yes, all checked and at the right places (several times even, as
> powering up blows them :) ).
>
> Last night, I started going through everything looking for dead
> shorts, no luck at the moment but there's a lot left. After taking
> the power brick out to check below the case, I did notice the
> transformer is a replacement and has been spliced in. Initial
> comparison with the wiring diagrams seem to indicate it's all done
> correctly but I'm going to give it a lengthier check tonight.
>
> Colin
>
>
>
> On 01 Dec 2009, at 02:12, teeray wrote:
>
>> 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
>>>>>>
>>>>>>
>>>>>>
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>>>>>
>>>>>
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Received on Sat Dec 5 18:53:46 2009