Saved a Taito Space Invaders

So leading up to Christmas I had an Ebay notification about a SI for sale, jumped on and had a look.  Now I have a Midway that I have not got around to sprucing up but its a worker (well until a few weeks ago when the monitor started going out!)

But I have always preferred the Taito from a cosmetic point of view. It was being advertised as perfect to be Mame'd and the seller was including a Jamma harness, buttons and joysticks and an LCD screen.

I could not let this happen.....

Made contact to see if we could agree a BIN price which we did, I explained I wanted to restore it to original not convert and he agreed to sell to me.

So it had all the parts there that were important.

Good points:

Power Supply, CRT, Board Set, CP were all in place

Bad points:

The bezel was missing, CP broken, joystick missing

So it turned up and I was pleasantly surprised it is in good condition considering its age and I did not need to do anything to the sides or main structure.

The cash door was present just not shown in the pic, and the bezel had been forcefully removed so had broken the wooden lip that it sits in.

Wood filler and a new square dowel fitted to create the slot for the bezel to fit in, then created the bevel edge as required.

Ordered a new bezel and CP overlay from Olly and whilst waiting for them I cracked on with the joystick situation.

Turns out it had been sheared off and part of it was still in the mechanism.  I managed to source a similar one from a member but it was a smaller one but would do, until I had an idea.  I found a joystick and shaft that was pretty close on ARCADEWORLDUK.com, looking at the pics on the internet it seemed it should be a white ball top.  My neighbour is retired and does lathe work in his garden shed. So I popped around and we had a chat about him reducing it down as required and running a new thread up it. I have to say he did a sterling job.  He also reduced the overall width of the replacement CP overlay bolts that I got from Olly as well so they are close to original size (old ones were too rusty to keep as and I could not unscrew them so had to cut them off)

My crude drawing after measuring the joystick mechanism for him to work from.

Next was a check on the power up of the cabinet with board and chassis disconnected to see what is going on.  This was horrendous!  When I see joints cobbled together with different cable and terminal block I am always cautious.  I have worked on some interesting electrical installations in my time so I trust no one!

This was no exception, in essence the incoming live was wired to the earth of the cabinet, as you can see nicely soldered and not insulated, incoming neutral to the live of the cabinet and the incoming earth to the neutral of the cab  WTF!

I did a temp correction off this and fired up the cab, the power supply was dead, but the tubes worked and so did the chassis / CRT - result.

Ordered a switcher from Arcadeshop with the adapter, I may rebuild the original PSU but for now the switcher will give me what I need.

I replaced this with an inline plug & socket and new flex.

Next was onto a recap and check of the chassis, started OK, but on checking the two fuses on the ISO frame they just fell apart so these were replaced with what I had to hand, and I also did a full cap kit.

The coin door looked like it had been opened with a hammer so I spent some time straightening and filling and getting it looking as best I could, I really did not want to swap it out.  Overall it came out OK and passes as suitable I think.

So after getting the switcher and trying the board set it failed to boot, starting as a reset issue.  I spent quite a bit of time working on this with help from people, and after getting the test EPROM sorted and mending numerous broken tracks and replacing a lot of IC's, then RAM I finally got the test EPROM running and then the chassis crapped out.

Total loss of sync, managed to get a set of schematics for the Toei GM20 chassis from someone hre (so many helpful people) and reached out to several experts on here (we know who they are aka GUNBLADE) I was getting nowhere slowly, so also reached out to Randy Fromm.  Had a one hour video call with him (what a great and very clever guy) and my trusty scope and we narrowed it down to somewhere around Q4 where the sync pulse is stripped out of the composite video. Q4 was fine and I finally found one of the four resistors R20 connected to the base of Q4 open circuit.  Replaced and all sorted, this held me up by quite a few weeks along with the board issues.

This was the Braze kit running and not being able to get horizontal or vertical sync.

This was after replacing R20 and using an alternative source for video so as to rule out any board issue, still need to do some tweaks to the picture but that's simple enough to sort.

So really it was just completing the cosmetics now.

New bezel from Olly test fitted, I edged the sides with a rubber seal and got the bottom edging from a Pinball supplier as it has the lip allowing you to lift the bezel up and clear like you get on the back glass on a pinball machine.

Still needed to sand the repair down and paint.

Final touches to the base and the bezel repair also completed. Also painted the top brackets as well.

Ready to be moved to the games room.

Side view, it has some dinks in it but is really not worth trying to sort out it is a fine example for sure.

It has now taken its place in the games room ready to be played.

If only that as the end of the story, it boots up fine into the multi game kit but as soon as I choose a game it either resets or hangs!  Not the kit as I have another which I tested with same results so something on the board is still not right.  I have a spare set that are away for repair so hopefully in the next few weeks it will be finally be fully up and running!

So glad I saved this from a fate of being Mame'd and kept it as original as I could. I was really torn as I have the Midway that has anew home in my buddies soon but glad I pulled the trigger on this.

That's a really nice job!

Space Invaders is such an iconic cab and yours looks lovely.