Re: Star Trek pic waving?

Thank you John for your reply. You are always keen to help out and it is much appreciated. Thanks for the links and tips. I have been through the very useful faq in detail many times and I have taken its recommendations to heart. I did indeed install the extra grounding wires between the supply and the monitor and the game boards. I am using the original supply but I have yet to re-cap it, although I plan to do that very soon. I'm hoping that will solve the jitter problem. As far as I can comprehend, I have installed every upgrade known to mankind with respect to the monitor. I also have strapped the transformer to run the system at a slightly lower voltage.

William Boucher

  ----- Original Message -----
  From: John Robertson
  To: vectorlist@vectorlist.org
  Sent: Thursday, November 26, 2009 11:58 AM
  Subject: Re: VECTOR: Star Trek pic waving?

  William Boucher wrote:
    Just wondering if any Sega Star Trek experts out there might know what is causing my GO8-003 monitor to show a very slow kind of a jittery wave. The wave travels from right to left and also bottom to top about once per 5 seconds. The vectors are all correct and are nice and bright. The wave is not an absence of lines but is a shaking of them. The shaking tends to be only within about a 1 inch wide swath at a time. Vectors in other areas are rock steady. For example, when the 3D area is showing a green station, the lines separate from each other by about 1/8" as the wave passes by. The game is totally playable and the sounds are good.

    I just recently rebuilt the entire monitor, all new caps, diodes, transistors, many resistors, and all new headers and sockets and trifurcon wire terminals.
    My parts list for the monitor is available here: http://www.biltronix.com/arcade_electcomp_01.html#GO8_parts

    I have just today generated a Digikey order of components so that I can renovate the power supply. At present, it is not yet restored but all the outputs are bang on. I haven't checked the outputs for ripple yet (say due to bad caps).

    Anyways, just wondering if anyone has seen this problem before and knows the root cause and would care to share their experience.

    Thanks in advance...

    William Boucher
  Have you upgraded the ground connections from the power supply to the logic boards and monitor? I assume you are using the original power supply and not a switching power supply.

  You will need to fix this or you run the risk of damaging the monitor if the ground reference shifts enough to bias the drive transistors enough to blow them.

  See page 36 of the Electrohome GO-8 FAQ covers the ground upgrades and reasons:
  http://arcarc.xmission.com/PDF_Monitors/FAQ%20Electrohome%20G08%20Version%200.8%20dated%2025%20Feb%2020.pdf

  And power supply upgrades from the Sega XY FAQ @
  http://www.mikesarcade.com/cgi-bin/spies.cgi?action=url&type=info&page=segaxyfaq1.6.txt

  ===========
  Power supply
  ============

  Sega/Gremlin power supplies are not the most reliable. If you have a dead one,
  you have a few choices: you can repair it, or replace it.

  In most cases repairing these power supplies is straight forward. If you open
  it up, you'll see there's really not much to it. The voltage regulators are
  all mounted and can be easily replaced.

  If you decide to modernize your game and put in a switching power supply, there
  are a few things to consider:

  1) The Sega/Gremlin power supply has a built in audio amplifier. You'll need
     to provide your own if you replace it. I've had good luck with using the
     Bally Midway Dual audio amps as a replacement, but any audio amp should do.
  2) You'll need a 3VAC supply for the power-on reset. I've heard that using
     +5VDC as a substitution may work, but your milliage may vary.
  3) You'll need +5VDC, -5VDC, +12VDC, and -12VDC. John Robertson says you
     may be able to get by with substituting -5VDC for the -12VDC for the video,
     but you'll need to adjust your picture.

  Or if you wish, you can use a switching power to supply the more common
  voltages and keep the old power supply in there and use it for the things that
  may still work (audio amp, 3VAC, -12VDC). Just make sure if you do this to
  make the grounds common between the two power supplies.

  John :-#)#

-- 
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Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames)
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