G05-801 Blinking Spot Killer Plays Blind

neopolss

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Here's what I initially came into: The game pcb would be lit, would play blind, spot killer would light here and there, no picture, good neck glow.

I turned the machine on and off a few times, checking various things, changing brightness, contrast (turning both down), checking x & y output. No changes.

I turned the machine on again, now the machine would sound like it is beeping, timed with the spot killer light flashing, lights on the control panel flashing at the same speed. No picture, good neck glow.

I powered off and on a few times while taking voltage readings. +5v to the game board was around 4.80v I adjusted up to around +5, now the game is playing blind again.

It's back to square one. The spot killer light faintly comes on, back off, comes on. neck glow is constant. You can almost hear a sound like it trying to do something, coming from the Power section of the G05 (not the HV cage).

My first guess is to shotgun the power supply board on it. It's disgusting. I'm frankly not sure how it even ran. Two of the caps are for sure bulging on it. I will probably replace the transistors too. Beyond that I figured I'd go ahead and replace the caps on the deflection board and the bridge rectifier. There's no blown fuses or burned components anywhere. In fact, aside from the power supply board, the rest of the cab and pcbs are very clean.

Does anyone else have any thoughts on what may be happening?
 
Is this an Asteroids or a Lunar Lander ?

Sounds more like a board problem or edge connector problem or maybe even a big blue problem but I would still rebuild the PS, the monitor and replace those 2 huge caps on the regulator board.

Edit: if it's an Asteroids get the HS save kit.
 
Its an early asteroids. Serial 8000 or so, with owl door. Ill replace big blue for good measure, good call on checkng the harness. I overlooked it.
 
Re-seat all the chips on the motherboard. If the game is a keeper then go through it all. Make sure your fuse holder is solid and grabbing the fuses tight and the fuses are not corroded.
 
Haven't seen this on a G05, but bad caps in the V2000 spotkiller circuit can cause it to enable when it shouldn't.
 
I have seen this several times, and typically it has been an issue with the video output on the board. Test your board in another Asteroids if you know someone that may have one before messing with your monitor.

I learned that lesson the hard way...
 
Guru, i believe that you are correct and thatthis is a board issue.

Update on this:

Recapped deflection board, power board, replaced bridge rectifier, changed out transistors on the power board. Absolutely no change in behavior. Monitor has good neck glow. Spot killer light is on. Nothing burning or sparking. You can hear a faint beeping sound. Player buttons are rapidly blinking. Main pcb board has solid red light. X out measures 12v and y out is at 7.5v, but z out has very little voltage, maybe .10v at best. Havent recapped the oard but plan to. Harness is good and snug, checked all the pins and voltages from the a board are spot on.

Any thoughts?
 
Guru, i believe that you are correct and thatthis is a board issue.

Update on this:

Recapped deflection board, power board, replaced bridge rectifier, changed out transistors on the power board. Absolutely no change in behavior. Monitor has good neck glow. Spot killer light is on. Nothing burning or sparking. You can hear a faint beeping sound. Player buttons are rapidly blinking. Main pcb board has solid red light. X out measures 12v and y out is at 7.5v, but z out has very little voltage, maybe .10v at best. Havent recapped the oard but plan to. Harness is good and snug, checked all the pins and voltages from the a board are spot on.

Any thoughts?

Sounds like a PCB problem. What happens in test mode?
 
I am going to try it out tonight. The game is not with me but with a friend. I will post the results. I'm also going to try the pcb in a working asteroids just to narrow it down.
 
I swapped it out into a working asteroids cabinet. Same issue on it. Spot killer is lit, player buttons blink. I swapped back the working board and now it is having issues too. awesome. Somehow I disturbed its zen state.
 
Test mode gives three beeps and one low beep. Also, i see that a leg is cut on the chip at C4. Any ideas?
 
Yes, it is a speed up hack. Confirmed also that the board blows the 3 amp fuses on the power brick. It did this in my good machine also. What does that mean?
 
Yes, it is a speed up hack. Confirmed also that the board blows the 3 amp fuses on the power brick. It did this in my good machine also. What does that mean?

Those fuses protect the 36VAC lines. Those go straight from the brick to the PCB. See the attached diagram for what they're used for. Check those 4 rectifier diodes first, but it's possible another component, or some damage or bent pins/components, is causing it. You should be able to verify the problem by measuring a very low resistance between those edge pins (X & 20) on the PCB.
 

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X and Y out should not have very much (if any) DC voltage... they should swing between 4 and 6 volts AC. That plus the blown fuses would suggest the three-legged voltage regulators 7805, 7812, 7815 and 7915. If the fuse does not blow immediately, you can carefully measure their output to find the bad one. They each get 23 volts going into one of the pins, ground on another, and then +5V, +12V, +15V and -15V respectively. Or just replace them - they're about $1 each.

If they were bad they may have also killed the TL081 and/or TL082 (the eight pin chips).
 
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