Asteroids - HS Electrical Project - Help

XY

Dokert said:
If you have normal game sounds when play is pressed it is playing blind. If it is playing blind, you have a monitor issue.
Click to expand...

Not always true.

Just because it is playing blind DOES NOT mean there is video coming out of the board. You can use a simple volt meter to check the xy swings to see if it is putting out video if you cannot figure out your scope. Could be a board issue, monitor, connector issue or all 3.. After you check to see if you have video comong out of the board. If you dont have any. Try reseating the socketed chips on the game PCB to see if anything changes. If you do have video out of the board, Reflow the headder pins on the monitors deflection PCB. Common failure point.
 
7146aaron said:
Not always true.

Just because it is playing blind DOES NOT mean there is video coming out of the board. You can use a simple volt meter to check the xy swings to see if it is putting out video if you cannot figure out your scope. Could be a board issue, monitor, connector issue or all 3.. After you check to see if you have video comong out of the board. If you dont have any. Try reseating the socketed chips on the game PCB to see if anything changes. If you do have video out of the board, Reflow the headder pins on the monitors deflection PCB. Common failure point.
Click to expand...

I will concede that point.
 
Thanks for suggestions, talon and others.

We will try these this coming week.
 
Played with this a little with a couple students today

1. Testing across x/y test lug to board gnd lug, no AC voltage at all.

2. Reseated all chips. Lost game play. Now the P1/P2 led switches are always on, not flashing. No sound of game play.

3. Not sure if a chip was reversed. I assumed they would only fit one way, so one or more might have been reversed. Does it matter if they were reversed? How do I know the right orientation?

Is there a source for all these chips? The ones in the board were old and brittle. They can't cost too much to replace?

Looking at a couple of PCB boards on ebay.

4. What is input pins on DAC? Where are the opamp stages?
 
There is a dot or notch at one end of the chip, that corresponds with the notch at one end of the socket. Usually installing them backwards will blow the chip. Cost of the chip varies, pretty much by the rarity of the chip and or if it needs to be programmed.
 
I'd check the processor before anything - its easy to put it in backwards (all chips can go in backwards, there's no key on them). Chances are it might survive.

If you look at other chips, you'll see the little notch Dokert mentioned. In most cases they all point in the same direction...the socketed chips should follow the same direction. The process doesn't though because its perpendicular to the rest. The processor should go in so that the notch faces the inside of the board, not the edge.

Notice the notch on all the chips are on the same side...

ast-cpu1.jpg
 
We have done some work as detailed below, still no success. Any suggestions are appreciated.

1. Bought a new PCB, but it made no difference. I addition, the game stopped playing. Now sound is distorted, seems to buzz then game noises, which are not right, then other crap. Printed out audio board schematic to test.

2. Discovered that the power board output which is supposed to be 10.3 is less than 1 volt. Kids were using the AC setting, and not getting right result. On DC, the 10.3V is about 1/2 volt. One diode is testing differently than the other (2 diodes under the power supply which show in line with the 10.3 VDC output). One diode also shows heat discoloration on the board, and possibly the diode. We are not sure how to test the capacitor. Regardless, this voltage feeds the monitor, and might be one problem?

3. Cleaned the contacts on the PCB, but could not find a way to release the pins in the harness so they can be bent to make better contact. Any idea how to do this? They don't seem to have a release point like some in pinball machines I have worked on.

4. The 1/2 player LEDs never flash anymore (at least we don't see them flash-aren't always watching them).

I want to send the PCB boards to be checked out. What is the best place that does that. There is one on ebay (in Texas), but I have no experience other than buying working boards from someone.

Thanks
 
Power brick

PM me your address and I will send you a tested, working power brick for free. That way you will know what the voltages are supposed to be and you can diagnose yours from there. I would assume the Big blue capacitor has gone bad on yours and possibly the rectifier.
 
dyrwolf said:
We have done some work as detailed below, still no success. Any suggestions are appreciated.

1. Bought a new PCB, but it made no difference. I addition, the game stopped playing. Now sound is distorted, seems to buzz then game noises, which are not right, then other crap. Printed out audio board schematic to test.

2. Discovered that the power board output which is supposed to be 10.3 is less than 1 volt. Kids were using the AC setting, and not getting right result. On DC, the 10.3V is about 1/2 volt. One diode is testing differently than the other (2 diodes under the power supply which show in line with the 10.3 VDC output). One diode also shows heat discoloration on the board, and possibly the diode. We are not sure how to test the capacitor. Regardless, this voltage feeds the monitor, and might be one problem?

3. Cleaned the contacts on the PCB, but could not find a way to release the pins in the harness so they can be bent to make better contact. Any idea how to do this? They don't seem to have a release point like some in pinball machines I have worked on.

4. The 1/2 player LEDs never flash anymore (at least we don't see them flash-aren't always watching them).

I want to send the PCB boards to be checked out. What is the best place that does that. There is one on ebay (in Texas), but I have no experience other than buying working boards from someone.

Thanks
Click to expand...

The 2 diodes under the power supply are a common point of failure. You will need to remove them from the little board to accurately test them. If they are .400 to .600 as read in diode test with a dmm and open when read in the other direction they are good. These can be replaced with 6A diodes that are still sold at Radio Shack today.
 
Still looking for tips on how to bend the metal clips in the harness attaching to the PCB so they will be tighter against the board. Is there a way to release them so they can be pulled out of the plastic housing?
 
The original housing used was made by AMP, and they are no longer available. The replacement is made by Molex, and they are readily available.

The pins do release from the connector and come out, but with the old AMP housing sometimes they break when you release the pins. Sometimes the pins break off when you pull them out, and then you are screwed as they no longer make those pins.

The best way that I have found to tighten the pins is to use a metal scribe to bend the pins. Kind of like a dental pick except stronger.
 
Thanks. I am sending the boards for repairs over holiday break.
 
You must log in or register to reply here.

Similar threads

DZA
Omega Race HS Save Kit Help
Replies
7
Views
409
DZA
DZA
Picked up another Asteroids...
Replies
12
Views
470
Atari Force
Atari Force
Asteroids Graphic Glitch
Replies
14
Views
571
andrewb
andrewb
Asteroids wild northern lights halo?!?
Replies
4
Views
236
andrewb
andrewb
Lamonsoff
Asteroids LF353 TL082 Incompatibility
Replies
3
Views
327
Lamonsoff
Lamonsoff
Back
Top Bottom