What's wrong with my V2000/G05 B&W vector monitor?
Okay, a lot of folks seem to be confused about how these things work. These monitors are very simple and easy to work on, but are a bit different from their raster breathren. In my experience, the single most common failure bad solder joints on the P100/500/600/700 Molex headers. Simply reflowing those fixes a staggering number of issues with these monitors.
[size=+4]Things you should know[/size]
[size=+4]Monitor Models[/size]
[size=+4]Troubleshooting[/size]
I have...
[size=+4]Further reading[/size]
Okay, a lot of folks seem to be confused about how these things work. These monitors are very simple and easy to work on, but are a bit different from their raster breathren. In my experience, the single most common failure bad solder joints on the P100/500/600/700 Molex headers. Simply reflowing those fixes a staggering number of issues with these monitors.
[size=+4]Things you should know[/size]
- Unlike raster monitors, the filament voltage comes from a secondary winding in the cabinet's main transformer, not the flyback. So presence of neck glow does not indicate that the flyback & associated circuitry is functioning.
- The chassis transistors should have no continuity between the casing and the monitor frame when the harness is unplugged fromt the deflection board. If they do, you're likely to blow F600/F700 or the frame transistors.
- A correctly operating vector monitor produces "chatter" -- high-pitched intermittent sound from the yoke, as current flows and reverses to deflect the beam. A raster monitor has a similar sound, but more regular, as the beam is always deflected in the same pattern. A vector monitor deflects the beam arbitrarily, so the sound changes based on the image being displayed.
- Confoundingly, the LEDs on vector monitors are off when they are operating correctly, and on when there is a problem, which is the inverse of nearly everything else.
- The big ceramic resistors at R100/R101 were removed in later revision of these monitors, and are not necessary for correct functioning. I generally leave them alone if they aren't faulty, and bypass them if they've failed. Solder 18ga wire across their pads on the bottom of the PCB if you want to bypass them.
- Most adjustments are on the game PCB, not the monitor.
- Lots of problems can be caused by faults on the game PCB. When in doubt, swap PCBs/monitors with a known good part and see if the symptom follows.
[size=+4]Monitor Models[/size]
- Electrohome G05-801. 19" only. First version of this monitor, commonly found in Lunar Lander and early Asteroids. There are three PCBs in this monitor: power (center), HV (left), and deflection (right). These can be hacked to accept components from other models, but are the oddball of this family and have some difficult to replace components.
- Electrohome G05-802. 19". New design with two PCBs; HV cage on the left, deflection board on the right.
- Electrohome G05-805. 15". Identical to the -802, except resistors R604/R704, which are both 750Ω instead of 910Ω & 820Ω, respectively. You can convert between -802 and -805 by replacing these resistors.
- Wells-Gardner 19V2000. 19". These are very similar to the G05-802, and all the parts are interchangeable.
- Wells-Gardner 15V2000. 15". Unlike the Electrohome, the V2000 deflection board is the same for 19" & 15" models. Instead, the 15V2000 yoke has higher resistance to create a smaller image. Everything except the yoke is interchangeable with the other monitors.
[size=+4]Troubleshooting[/size]
I have...
- No image at all, and...
- No neck glow
Reflow P500 header, check fuses at the brick & continuity to the monitor; the pins in the molex at the power brick sometimes slip out. Filament voltage is not fused in the monitor; the fuse is on the power brick. Check it. - The spotkiller LED on the deflection board is lit
You have power, but no video signal. Reflow P600/P700 headers, check frame transistors, make sure F600/F700 are not blown & are correct values. - Spotkiller is off, I can hear deflection chatter, but have no static on tube face
HV problem. Reflow headers, check F102, replace HV diode. - Monitor has glow, spotkiller off, no deflection chatter
Monitor power problem. Check input power, fuses F100/F101, DB100. - Monitor completely dead
Monitor and/or cabinet power problem. Check input power, fuses F100/F101, DB100, P500 header, fuses for filament on power brick.
- No neck glow
- Bright dot in the center of the display
No video signal. Turn brightness down before you ruin the tube. Start over at "The spotkiller LED on the deflection board is lit." - Partial image, missing one or more quadrants of the image OR horizontal/vertical collapse
Reflow P600/P700 headers, check frame transistors, check F600/F700. - I can see parts of the image (like bullets/saucers), but not others
Adjust the brightness and contrast pots up. - Spiderwebs connect everything
Adjust the brightness and contrast pots down. - Image is jumpy
Replace linearity pots. - Image "breathes," getting larger and smaller
Bypass R100/R101, replace HV diode, replace lytic caps. - Image is too large, but size is steady
Adjust size on game PCB, replace lytic caps. - Parts of the image fade in/out
Bad caps in the spotkiller. Look in the back & if you see the spotkiller LED lighting up / flashing / pulsing, that's a giveaway. You can just replace the caps in the 500 section, but you may as well do them all. - Some other problem
Welp, time to break out the schematic. Turn the brightness up and see if you can see anything that would give you a clue. Lots of issues can be caused by failed components in the preamp circuits, in particular Q602/3/4/5/6/7, Q&02/3/4/5/6/7. Passive components can also fail, so start testing things one at a time in the circuit you suspect.
[size=+4]Further reading[/size]
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