Solved Asteroids Help

[the-hat]

Hi guys,

Im trying to put my Asteroids together with the pile of parts I have, anyway the brick I have is from Battlezone and is slightly different and with a different plug. I checked the docs and they look compatible so ive changed the plug so they fit following the wiring diagrams. the game board powers up, the spot killer led flickers once then goes out and it sounds like I have vector chatter from the monitor but the neck doesnt glow and I get no picture, dont know if there is HT or not. The 30v-0-30v is correct at the monitor plug. I checked the 6v AC and when the monitor is connected it is 0, but if I disconnect the monitor it is correct. The fuse(s) does not blow.
I have tried a 2nd 15" monitor I have and get exactly the same syptoms.
Does it mean the brick is bad ?

Thanks in advance for any help

 

[Mc-Q]

it could just mean you have the video position/brightness out of ajustment.
i presume you dont have a scope.
meter the x,y and z lines while it's running - ideally at the monitor connector - see if you have a signal on all 3 pins.

 

[the-hat]

ok had a look at that, now this is also confusing. according to the G05-802 book / schems the pinout should be:
1. X in
2. X gnd
3. Y in
4. Y gnd
5. Z in
6. Z gnd

but the wiring on the plug doesnt look like that, see pic, they are in pairs and look like 1 and 4, 2 and 5, 3 and 6

its definately vector chatter I can here, there is 95v where there should be 90v on the output of the deflection board that goes to the HV power supply, the only thing that isnt coming on is the tube heater. Ive tried turning up the brightness and contrast but no picture. If I measure volts DC according to the pinout in the manual there is 0 on the Z input, if I measure it in the 3x pairs It looks like in the plug then I get voltage on all 3 inputs .. Anyone got an asteroids they can look at the monitor plug on ?
thanks,

 

[the-hat]

ok i checked the asteroids schem pack and the wiring of the plug is right, the g05 manual is different for some reason. anyway there is voltage on all 3 inputs and it moves around depending on the "chatter" i can hear.
Would the heater not working stop me getting any sort of picture ? like i say the voltage is fine until i plug the monitor in then it goes to 0 , or if I leave the monitor unplugged and connect the coin door, it also zero's. Im leaning towards the brick being bad ?

 

[tb lilley]

Yes, you'll not get a picture without the heater voltage. Coin door lights draw from the same 6VAC off the brick. So it is possible that the brick's 6VAC is failing under load. But first thing I'd check is that the relevant fuse holder (F6?) is giving a nice tight fit, and that fuse ends and holders are clean.

 

[the-hat]

genius, it was a bad connection on the spade connector on the output of the fuse !

all working !

Thankyou

 

[Mc-Q]

question:
does the power brick have a pcb stuck to the big cap with 2 diodes on it, or does it have a bridge rectifier bolted to the chassis?

 

[the-hat]

it has a bridge rectifier

 

[Mc-Q]

good - the ones with diodes arent reliable