Re: G08 Star Trek with no HV

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
>>>---------------------------------------------------------------------------
>>>** 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

-- 
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"
---------------------------------------------------------------------------
** Unsubscribe, subscribe, or view the archives at http://www.vectorlist.org
** Please direct other questions, comments, or problems to chris@westnet.com