Problem Taito Space Invaders Cocktail

[London Pinball]

Hi,

I am trying to get this original machine up and running. It was totally dead until I reflowed some dry joints on the power board. Any suggestions as to where I need to look next? I have no schematic diagrams or info on where to check voltages which would be helpful.

Thanks in advance

Matt

 

[davey d]

The monitor is obviously working, but the flyback transformer needs turning down, as you can see the raster lines on the monitor

 

[London Pinball]

Forgive my ignorance but how do you do that exactly?

 

[Funhouse71]

On the back of the flyback there will be adjustment screws, one for focus and one for screen try adjusting the one for screen.

 

[ArcadePCB]

When done the monitor issue, after checking the voltages, check the reset signal first. The reset signal is generated on the power supply pcb, so the game pcb will not run using any other power supply without reproducing the reset signal with an external circuit (e.g TL7705) or applying a manual reset (for test puroses only). If OK, check the CPU clock signal next.

 

[London Pinball]

Is there is resource for where and what test point voltages to check?

 

[ArcadePCB]

I've just found this. Better than nothing, but without the schematics of the boards. There are many documents for the upright version (different pcbs, 'L-shaped'), but most of the schematics should fit.

 

[Lurch666]

Isn't one of these any good?

Space Invaders Manuals @ www.robotron-2084.co.uk

www.robotron-2084.co.uk

 

[ArcadePCB]

Really good site I didn't know yet. Check if one of the manuals matches your boardset.
The sites I've checked provided Space Invaders Part II (later colour version) manuals despite labeled Space Invaders.

 

[Stickman]

What board set do you have in the cocktail 2 or 3 layer I was trying to see in the picture? First thing is to make sure that you are getting the required voltages to the board, the site mentioned above is a great resource for SI schematics, once you can confirm the +5,-5 and 12v are all present the next stage is to see what if anything you get on the screen, usually if the board tries to start up but is missing the reset toggle (this is a state change sent to the 8080 processor to kick it into run in essence) you get a screen of garbage, this toggle is usually done by the power supply. Depending on your level of understanding you can start checking things with a logic probe or scope to try and track down what is going on, there is also a test ROM you can make to test everything but you would normally only be able to do this once you have garbage on the screen and it seems to be changing. If you feel this is not for you to get into as deep there are a few people that repair these boards and being less complicated not too expensive. I spent a long time working on a L shaped board to get it working and it still gives me grief (I did drop it after getting it going!) so is my backup.