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

Colin O'Brien wrote:
> FInally got some spare time to check this out today. The voltage at G1 is climbing, others (G2 etc) are stable.
>
> Thoroughly inspected the board but all components check out ok, even replaced a few just to be sure. The thing is this voltage increase seems to be coming into the board from G1.
>
> If I set both pots to 0, I start out with 0V at Pin 2 of P500 (G1). Then it starts climbing, I remain at 0 or close to 0 on the pot side of R518 but on the P500 side it keeps growing to about 50V when I cut it off to avoid damage. At that point everything is very bright and retrace lines are visible. A quick check to other pins shows no change.
>
> Not sure where to go from here.
>
> Thanks,
> Colin
>
>
This sounds like a problem with the HV section. Can you pull it out and
set it on the bench and feed it 35VDC to see if the HV and other
voltages are stable? I put the HV lead into a ceramic cup to avoid
shocks, and leave a HV probe touching it to monitor the HVDC...if it
changes, turn off the HV and then feel the HV diode - as it is not
connected to a picture tube there will be no stored charge - it should
only be around room temperature or warm to the touch, hot means it is bad.

A quick side question - are you sure that you are using two IDENTICAL
monitor boards? Electrohome and Wells Gardner both made B&W chassis that
look similar but (AIR) can't be plugged into the others chassis.

John :-#)#
>
> On 07 Dec 2009, at 23:39, Colin O'Brien wrote:
>
>
>> Indeed, the voltage to G1 (P500 pin 2) is slowly climbing. Other voltages on that connector seem relatively stable.
>>
>> I'm going to pull the board and check components in its path. As I have 2 boards exhibiting the same symptom I guess it's possible that my previous problems could have damaged the same area on both.
>>
>>
>> Colin
>>
>>
>> On 07 Dec 2009, at 19:23, shenlung@verizon.net wrote:
>>
>>
>>> Sounds like the screen voltage is whats changing. Effects the beam current of tube, more beam current brighter lines. Do the normally on lines get brighter with the retrace? if so something unstable in screen grid (brightnest circuit). If only retrace appears and drawn lines stay same, I guess something maybe in the Z circuit. If the HV changes the pic normally will be blurry and start blooming. sounds like the HV is fine. I haven't worked on one of these in awhile but back in the 80's I used to fix them all the time. Also maybe the tube has low emission and the gain is cranked up to compensate, as the tube warms up the emission increases then its overdriven.
>>>
>>> Thad
>>>
>>>
>>> Dec 7, 2009 05:50:19 PM, vectorlist@vectorlist.org wrote:
>>>
>>> ===========================================
>>>
>>>
>>>
>>> I'll give it a go. I did clean the fuse block and replace the fuses
>>> back in the beginning but didn't touch the molex connectors. I
>>> measured a steady 6.3 but never looked at it over time either.
>>>
>>> Last night I reflowed a few connections just in case, but had no luck.
>>>
>>> On the other hand, the problem may be linked to heat somewhere. If I
>>> leave the game off for a while, it takes longer to to reach the
>>> visible retrace lines point than if I power it back on shortly after a
>>> previous session.
>>>
>>> I measured the HV and it starts at 12.64 (which seems a bit high) and
>>> slowly creeps up to 12.73 when the retrace lines show up. It may go
>>> higher but I don't want to damage the tube so I power down at that
>>> point. Not sure if such a change can be considered within acceptable
>>> limits or not.
>>>
>>> Colin
>>>
>>>
>>>
>>>
>>>
>>> On 06 Dec 2009, at 21:53, Matt J. McCullar wrote:
>>>
>>>
>>>> It's a long shot, but try checking/cleaning the fuse blocks as well
>>>> as all
>>>> the in-line Molex connectors. I once had an _Asteroids_ cabinet
>>>> that had a
>>>> flaky fuse in the 6.3 VAC secondary of the power transformer; it lit
>>>> up the
>>>> lights in the coin door, but it also went to the heater in the
>>>> picture tube.
>>>> The fuse itself was weak and had enough of a voltage drop that the
>>>> picture
>>>> tube wouldn't light up. Replacing that fuse fixed the whole thing
>>>> but it
>>>> took me a while to find.
>>>>
>>>> Matt J. McCullar
>>>> Fort Worth, TX
>>>> ***************************
>>>>
>>>> -----Original Message-----
>>>> From: owner-vectorlist@vectorlist.org
>>>> [mailto:owner-vectorlist@vectorlist.org]On Behalf Of Colin O'Brien
>>>> Sent: Saturday, December 05, 2009 5:54 PM
>>>> To: vectorlist@vectorlist.org
>>>> Subject: Re: VECTOR: 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
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>

-- 
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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