Re: G08 Star Trek with no HV

Well, I just found that Q202 and D201 were bad and replaced. Powered
up with no results. The other parts on the X-axis current limiter
tested ok.

Jeff

On Jan 21, 2007, at 1:04 PM, John Robertson wrote:

> At 9:06 PM -0600 1/20/07, Jeff Klammer wrote:
>> The saga continues. I replaced Q701-704 today for fun and
>> something interesting happened when I powered up. It sounded like
>> the high voltage fired up (didn't get to the front of the machine
>> quick enough) and then seconds later, a red hot ember dropped from
>> somewhere near Q703. I immediately pulled the plug to
>> investigate. It almost looks like paint off of the cap just to
>> the right of Q703 fell off and burned up when it hit the
>> motherboard. I didn't see any burned components. I got my fire
>> extinguisher ready and powered up again and everything tests the
>> same as my original post. I can hear the deflection chatter, but
>> still no voltage on pin 2. Could the paint chip have shorted
>> something to Q703 that would have fired up the high voltage?
>>
>> I used my transistor tester on my meter to check the ones that I
>> pulled earlier, and they all seem to test ok.
>>
>> Jeff
>
> Sounds to me like a tantalum capacitor failed. They can catch on
> fire/explode when they short if they are allowed too much current
> (over-fused?).
>
> You might want to figure out what burned before turning that
> monitor on again...
>
> John :-#)#
>
>> On Jan 14, 2007, at 6:52 PM, Jeff Klammer wrote:
>>
>>> Still no luck with this G08 chassis. How much would you charge
>>> me to fix it? I'm hoping to have it running by February 3rd for
>>> my kids birthday party. I think I may have hit my limit on
>>> troubleshooting this one. I saw a chassis on ebay, but it
>>> looked overpriced to me. How much should a working chassis go for?
>>>
>>> http://cgi.ebay.com/ws/eBayISAPI.dll?
>>> ViewItem&ih=016&sspagename=STRK%3AMEWA%
>>> 3AIT&viewitem=&item=260074424452&rd=1&rd=1
>>>
>>> Thanks,
>>> Jeff Klammer in St. Paul (White Bear Lake)
>>>
>>> On Dec 29, 2006, at 6:15 PM, Hans O wrote:
>>>
>>>> Yes, no voltage indicates trouble in the X deflection. If you
>>>> hear deflection chatter, you should have enough signal to
>>>> display something on the monitor. Usually the HV unit will still
>>>> fire up with one side of the deflection collapsed.
>>>>
>>>> Some things to check:
>>>> Cold solder joints, especially on the connector, HV transformer
>>>> pins, and T900. Reflow them even if they look good.
>>>> Check for approx. 100v coming out of the little HV board.
>>>> Measure the end of R307 nearest the screw hole.
>>>> Check Q900 (would it still be called the HOT?)
>>>> If so far, so good, then you need to start probing the
>>>> oscillator circuit. May be hard to do without a scope. Start
>>>> with Pin 9 on the IC. If there is no signal at pin 9, then the
>>>> IC is probably bad. Before you chuck it, fix the X section and
>>>> retest.
>>>>
>>>> If you have oscillation at pin 9, follow the signal through
>>>> Q901, Q902 (on the back of the board), and Q903. Next stop is
>>>> the end of R327 nearest the coil. Last stop is the Collector of
>>>> Q900 (yellow wire, I think).
>>>>
>>>> If you have oscillation up to the HV transformer, 100v feeding
>>>> it, and no cold solder joints, then the last suspect is a bad HV
>>>> transformer (highly unlikely).
>>>>
>>>> Hope this helps.
>>>> Hans O in Chicago
>>>> (If you get totally stumped, I can probably look at it for you.
>>>>
>>>>
>>>> Jeff Klammer wrote:
>>>>> Greetings. I just acquired a Star Trek with no picture on the
>>>>> G08 monitor. You can play the game blind and with the back
>>>>> cover off, you can hear vector chatter. The high voltage
>>>>> doesn't seem to be coming on. Here's the voltage readings on
>>>>> the 10 pin to the HV board.
>>>>> 1. Approx +2.4VDC
>>>>> 2. No voltage
>>>>> 3. -9VDC
>>>>> 4. +9VDC
>>>>> 5. GND
>>>>> 6. GND
>>>>> 7. No Voltage
>>>>> 8. 118VDC
>>>>> 9. 10. No Voltage
>>>>> I've done some initial troubleshooting on the G08 chassis
>>>>> (installed Bob Roberts kit), but I don't find any bad parts
>>>>> yet. Can I assume that no voltage on pin 2 means that the
>>>>> problem is in the X part of the deflection board? This is my
>>>>> first time troubleshooting a vector monitor. I'm hoping to find
>>>>> someone in MN with a good Star Trek or G08 vector game so I can
>>>>> narrow down the problem to the Star Trek hardware or the G08.
>>>>> I have read all of the archives and found one similar problem
>>>>> from Dec. 27 of 2005, but it looks like that problem was never
>>>>> solved (or at least never posted a solution). I've posted this
>>>>> on vaps.org also, but so far have not found the solution. I
>>>>> should have my scope up and running in a week or so which may
>>>>> also help troubleshoot.
>>>>> Thanks,
>>>>> Jeff Klammer
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>>>
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>>
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>
>
> --
> 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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Received on Tue Jan 23 18:57:24 2007