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Super Space Stranger Cocktail Repair Log

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Kaizen088 View Drop Down

Joined: 16 Aug 2015
Location: Brisbane, OZ
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    Posted: 11 Oct 2018 at 3:21pm
I have this cabinet in for repair at the moment.

Manual links:

The cabinet is in good condition but when first powered up there was no image on screen and not playing blind.
On closer inspection I found the composite video wire on the edge connector had broken off, it was resoldered and I was greeted by a crosshatch pattern on screen.

When I pulled the 8 x 2708 ROMs to check them 29 pins were corroded or broken.

I repaired all the broken pins and dumped them and surprisingly one of the chips that didn't have any broken pins returned a bad dump.
I burnt a new one and threw them back on the board and it booted up and played without sound.

The sound amp on these boards is an LM380 which was missing, there were a number of mods (cut traces and link wires) to that section of the board so I went through and confirmed it was correct as per the schematic. It looks like this PCB had a different type amp than what was shown on the schematic but the board has been modded to match it.

With a new LM380 fitted the board now had the 'footstep' sound only.
All LM3900 Op Amps were pulled and they all tested faulty.
New sockets and LM3900's in place and all sounds were restored but the footstep sounds were all the same pitch.

The resistor array connected to that part of the circuit was replaced with a diy array as I didn't have any 8x1k arrays on hand (only 5 outputs were used so 5x1k resistors were substituted).
This brought the first three tones back to the correct pitch but the last tone was higher than the previous one. It should be an 82k resistor which tested fine so I substituted it with a 120K (10k+20k in series) which brought the pitch down to the correct level.

Last thing to do was burn a new set of eproms and replace the sockets.
The sockets on this PCB are a pain to remove in the normal way with a desoldering gun (the holes are quite hard to desolder completely and with three voltages going into the chips the power rails sink a lot of heat away very quickly).
With these type of sockets it's easier to pry the top piece off as shown below, then heat the pins up with a soldering iron and push them through the board so the stick out of the socket, then I grab each pin and heat the hole with the desoldering gun and pull the pin out and clear the hole at the same time.

It's a bit more work but is quite efficient and no lifted pads, tracks or pulled vias.

New sockets and ROMs fitted and the game is now fully working.

The only other thing to do is adjust the monitor which I'll get around to tomorrow.

One interesting thing with this version of Space Invaders is that if you shoot the bases you lose 50 points for every hit.
The UFO also appears a lot more often than the Tatio/Midway ROM set.
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