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Vector G08 Series Faq

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The Evil, Infamous, Unreliable, Flaming...

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INTRODUCTION .............................................................................................................................. 2
MONITOR HISTORY........................................................................................................................ 3
PART DESCRIPTIONS ..................................................................................................................... 5
HOW IT ALL WORKS .................................................................................................................... 14
REPAIR PREPARATION................................................................................................................ 15
DEBUGGING THE MONITOR ...................................................................................................... 19
INSTALLING A CAP KIT .............................................................................................................. 26
MAKING THE MONITOR MORE RELIABLE............................................................................. 31
TUBE REPLACEMENT .................................................................................................................. 33
USING A G08-003 WITH COSMIC CHASM ................................................................................ 34
Appendix A: Common Ground Connections.................................................................................... 36
Appendix B: Testing Transistors ...................................................................................................... 37
Appendix C: Parts Lists .................................................................................................................... 39
REFERENCES ................................................................................................................................. 41
DOCUMENT HISTORY.................................................................................................................. 41
CAUTION: The Electrohome G08 monitor is extremely flammable. Do not operate around
combustible liquids or materials. This document should not be used to put out any flames caused by
Electrohome
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FAQ version 1.1
Oct 7th, 2002
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Summary of Contents for Vector G08 Series

  • Page 1: Table Of Contents

    The Evil, Infamous, Unreliable, Flaming... Electrohome _______ ________ ________ ____ ____ |__| | |____| | |_ ____ |___| | | |____| |____| \_______/ \________/ \________/ FAQ version 1.1 Oct 7th, 2002 Table of Contents INTRODUCTION ..........................2 MONITOR HISTORY........................3 PART DESCRIPTIONS ........................

  • Page 2: Introduction

    Ok, enough making fun of the G08 :-). It is actually a pretty strong monitor considering the work that it does, and when it is working it is a fairly impressive color vector monitor. There are horror stories about this monitor, and most of them are true (and the list is long), but on the other hand, there are others have had theirs for 15 years without it breaking down once.

  • Page 3: Monitor History

    Electrohome GO8. Don started at Sega/Gremlin in May 1981, while he was on recess from Cal Poly for the summer. He was hired initially to help design the Vector control and timing boards that are in the G-80 boardsets.
  • Page 4 They had already begun working on a game that they wanted to be vector, and decided they wanted it to be color as well. Initially, it reminded me of a vector version of Gorf, with the player being taunted by a weird alien during the game. None of the color routine was set up yet, (I think we were running a G05), and the game didn’t look very much like the final product at all.

  • Page 5: Part Descriptions

    G08 Vector Monitor Guide PART DESCRIPTIONS The following sections describe the different major assemblies of the Electrohome G08-003 vector monitor. Before we delve into the different parts of the G08 monitor, it is important to discuss the different schematics that exist. The best schematics to reference are included in the Tac/Scan, Zektor or Star Trek manuals.
  • Page 6 G08 Vector Monitor Guide The Input Clamp board has a pinout as follows: Pin # Description Specification Horizontal Input +/- 4V maximum Vertical Input +/- 3V maximum Common Ground Red Input +4V @ full brightness Green Input +4V @ full brightness...
  • Page 7 G08 Vector Monitor Guide Issue 5 deflection boards have places for resistors R636, R637, R736, R737 screened on top of the board. Issue 5 deflection boards may be found with or without diodes D601, D602, D701, and D702 populated. If your deflection board has these diodes, just leave them installed. They do not appear to make a functional difference.
  • Page 8 G08 Vector Monitor Guide The circuit of D409, R410, and R411, in combination with IC900 on the HV board, is a spot-killer that prevents the electron-beams from burning a hole in the phosphor surface of the CRT when the monitor is turned off.
  • Page 9 G08 Vector Monitor Guide • R635 and R735: Some G08 deflection boards have a ‘teepee’ of large ceramic resistors in these locations. As noted in the schematics, there should be a single 3-Ohm 20W resistor in each location. Some have been replaced with two 1.5-Ohm resistors in series. It is unclear why this modification was done to some G08-003 deflection boards (possibly cooling reasons?).
  • Page 10 150. However, the G08 uses +/-63 volts IDEALLY. So when the amplifier swings to the rail during a fast vector draw you have close to 125 volts. Remember I said IDEALLY? That is with the game plugged in to a 110-volt line, since that is what the Gremlin/Sega power transformer was designed for.
  • Page 11 The HV transformer (T901) is otherwise unavailable for replacement. These HV transformers are extremely reliable compared to all other vector monitors out there, but if yours does go bad, you will have to find another G08 HV cage for a replacement.
  • Page 12 G08 Vector Monitor Guide CRT Neck Board The CRT neck board is a 4” x 4” PCB with a large tube socket mounted directly in the middle of it. It connects to the end of the monitor tube. The board controls the color guns of the tube.
  • Page 13 G08 Vector Monitor Guide Part Number Summary This following list summarizes all the Electrohome part numbers for the G08 monitors. These numbers do not reflect the issue numbers between the deflection board revisions. Electrohome Monitor Part Number G08-001 Manual EHT Supply Assembly...

  • Page 14: How It All Works

    G08 Vector Monitor Guide HOW IT ALL WORKS Inputs come in from the game boards (most commonly the Sega G-80 system XY timing and control boards) and are fed into the input protection board. The input signals then go to the deflection board, and the deflection board does its stuff.

  • Page 15: Repair Preparation

    G08 Vector Monitor Guide REPAIR PREPARATION So you have a G08, and you have no idea of its condition. Well, let’s do a few basic things before we fire it up (“fire it up” might be a poor choice of words here ;-)).
  • Page 16 G08 Vector Monitor Guide Test the deflection transistors through the connectors. Please read the procedure in “Appendix B” before continuing. Unlike the Wells Gardner 6100 color XY monitor, which uses 2N3716 and 2N3972 transistors in a push-pull configuration, all the transistors in the G08 should be identical (unless you have an original G08-001 which used the MJ15003 for one set, and MJ15004 for the other set).
  • Page 17 G08 Vector Monitor Guide Most shorts will occur between the collector and either the base or emitter. If your test through the connector reveals a short, pull the transistor and test it separately. If it is good out of circuit, you may have accidentally shorted either the base or emitter against the heat sink, or the transistor socket may have been bent.
  • Page 18 G08 Vector Monitor Guide transistors on the deflection board do NOT TOUCH ANYTHING except the transistor it is trying to cool. Replace burnt resistors and loose capacitors. If you can, it is a good idea to replace all the electrolytic capacitors on the deflection board (except the LARGE ones), since these components tend to dry out and fail as they age.

  • Page 19: Debugging The Monitor

    G08 Vector Monitor Guide DEBUGGING THE MONITOR Ok, to debug the monitor, you will need a known working game boardset and power supply. Hook up the power and video inputs to the monitor. Now, unplug the connector that goes to the monitor yoke.
  • Page 20 G08 Vector Monitor Guide It is difficult to determine if it is the custom chip that is causing a problem. Here is a listing of the pins of the custom chip on the deflection board: Pin 1 wiper of height pot. Other inputs to pot are Y analog signal and Y yoke output...
  • Page 21 G08 Vector Monitor Guide WARNING: Working with monitors of unknown operating condition can be EXTREMELY dangerous. The Electrohome G08 is no exception. If fact, there are probably more horror stories about this monitor than any other. Proceed with extreme caution.
  • Page 22 G08 Vector Monitor Guide R918 on the HV unit. The HV unit may be shutting down because of the input signal sensitivity settings. Symptom: Fuse 600/700 blows Fuse 700: Check transistors Q703; Q704; Q705; Q706. Fuse 600: Check transistors Q603; Q604; Q605; Q606.
  • Page 23 Symptom: Occasional Extraneous Vectors On Right Side Of Screen Assuming you are using your G08 monitor with the Sega G-80 vector game boards, you will need to add the following two capacitors to the X-Y Timing board on the G-80 game boardset. Install two 100pF, 50V ceramic capacitors in locations C32 and C33.
  • Page 24 G08 Vector Monitor Guide Symptom: One Or More Colors Is Missing Check the transistors and diodes on the Input Clamp board for shorts or opens when one or more colors is missing from the display, and the G-80 boards are known to be good.
  • Page 25 G08 Vector Monitor Guide Voltages The following G08-003 voltages are measured during running of the monitor (taken from the Zektor manual): All Readings are DC Level Voltages B=BASE E=EMITTER C=COLLECTOR AN=ANODE CA=CATHODE D401 CA 63.0 D403 CA 63.0 D400 AN -63.0 D402 AN -63.0...

  • Page 26: Installing A Cap Kit

    G08 Vector Monitor Guide INSTALLING A CAP KIT Zanen Electronics Bob Roberts also sells cap kits. Bob provides a 5023 52nd Street kit for the G08 Vector Monitor. Lubbock TX 79414 806-793-6337 bob147@bellsouth.net Fax: 806-793-9136 http://www.therealbobroberts.com Zanen Kit #110 Key: •...
  • Page 27 G08 Vector Monitor Guide CAP KIT SUMMARY: There are some known problems with Zanen and Bob Roberts cap kits. Below is a recommended list of parts. Almost all of the suggested replacement capacitors are upgraded in terms of voltage rating and should make your G08 monitor last longer and run cooler. If you would like to make a...
  • Page 28 NOTE: The transistors shipped with the Zanen and Bob Roberts kits are 2N3716s. These transistors are not sufficient to work with the G08 monitor. Replace them with 2N6259s (if you can find them) or MJ15024s. Keep the 2N3716s for your other vector monitors! Deflection Transistors...
  • Page 29 G08 Vector Monitor Guide G08-003 DEFLECTION BOARD Not all of these parts are necessary for a monitor rebuild, but are good to have on hand. For capacitors, see “Cap Kit Summary” section above. NON-Zanen Deflection PCB Parts Location Part Description...
  • Page 30 G08 Vector Monitor Guide G08-003 HIGH VOLTAGE UNIT Not all of these parts are necessary for a monitor rebuild, but are good to have on hand. For capacitors, see “Cap Kit Summary” section above. NON-Zanen HV PCB Parts Location Part Description...

  • Page 31: Making The Monitor More Reliable

    G08 Vector Monitor Guide MAKING THE MONITOR MORE RELIABLE Ok, so now you have a working G08 monitor (hopefully). Here are just a few things you can do to the monitor to prolong its life just a bit longer. Input Clamp Board Modification Replace the tape on the back of the input protection board with a strip of electrical tape or other non-conductive material to prevent it from shorting to the metal bar it is typically mounted on.
  • Page 32 G08 Vector Monitor Guide (Pretty bad drawing huh?) The 0.39-ohm resistor allows the transistors to be hooked in parallel without one transistor going into thermal runaway and trying to drive the whole load itself. (A good place to find out more...

  • Page 33: Tube Replacement

    You can replace the tube. As mentioned before, the tube is the same as the one used in the Wells- Gardner 6100 series color XY monitors. You can also buy a brand new color vector tube (19VLUP22) from Richardson Electronics (1-800-222-2787) for around $165. It will not come with the tinted gel, nor a deflection yoke or convergence rings, so you will have to transfer those from the broken tube and reconverge the monitor colors.

  • Page 34: Using A G08-003 With Cosmic Chasm

    G08 Vector Monitor Guide USING A G08-003 WITH COSMIC CHASM Cosmic Chasm uses the G08-105 monitor, which takes slightly different inputs and is basically a better version monitor than the G08-003. It is, however, hard as hell to find the G08-105 monitor.
  • Page 35 G08 Vector Monitor Guide 5) Using a short piece of wire-wrap wire connect the each pot's #3 lead to the IC's #4 pin (- 15V). 6) Connect a 90.1K resistor between pin #2 of the IC and #2 lead of the pot for each.

  • Page 36: Appendix A: Common Ground Connections

    Vector mail-list got the following response from me...: Vector monitors blow up because the ground reference for the monitor drifts relative to the logic boards (MPU and video) when the power supply connections overheat. This will then bias the input signals offset enough to overdrive the outputs.

  • Page 37: Appendix B: Testing Transistors

    G08 Vector Monitor Guide Appendix B: Testing Transistors Most of the failures in the Electrohome G08 monitor (as is the case with most electronic devices) are semiconductor failures, specifically, the transistors. All transistors discussed in this document can be tested in the same way; it does not matter if they are the large chassis-mounted transistors or the tiny PCB-mounted transistors.
  • Page 38 G08 Vector Monitor Guide TESTING TRANSISTORS WITH A DIGITAL MULTI-METER Set your meter to the diode test. Connect the red meter lead to the base of the transistor. Connect the black meter lead to the emitter. A good NPN transistor will read a JUNCTION DROP voltage of between 0.45v and 0.9v.

  • Page 39: Appendix C: Parts Lists

    G08 Vector Monitor Guide Appendix C: Parts Lists The Input Clamp Board is only discussed in the Preliminary G08-003/004 Service Manual. Included below is the parts list. Not all of these parts a re necessary for a monitor rebuild, but are good to have on hand.
  • Page 40 G08 Vector Monitor Guide The Current Limiter boards are attached to the deflection board and are only discussed in the Preliminary G08-003/004 Service Manual. Included below is the parts list. Not all of these parts are necessary for a monitor rebuild, but are good to have on hand.

  • Page 41: References

    G08 Vector Monitor Guide REFERENCES 1. The 'Wiretap' Arcade Game Collector's Archive - http://www.spies.com/arcade/ Contains information about G-08 system games, as well as schematics for the monitor and game boards. 2. Star Trek Manual This manual contains the most up-to-date information on the Electrohome G08-003 model monitor.

This manual is also suitable for:

G08-003

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