Robotron cocktail

[Hurray Banana]

Not a complicated fix but thought I'd post this as not seen images of this checkboard before.

Game started crashing after being on a 30 minutes, putting garbage on screen. It would always come back on when powered off and on though.

Started crashing after a few minutes of being on and then eventually upon startup now get a solid black and red checkerboard screen in stays here doing nothing, no rug or startup sound whatsoever.

Resat all chips on rom board and check all interconnects. Upon startup got checkboard but also rug is showing every couple of checkboard columns, so cpu must be doing something, startup sound is triggering but just stays here cycling through the rug patterns.

looked at LED display on rom board

cycled between numbers 1 and 3 and 1

1 indicates a ram failure other 2 number indicate Bank 3 and chip 1

I'm using 4164 RAM's on my robotron so replaced 4164 at this location, game booted with pattern above but this time it got to the ram failure screen but reported the same location bank 3 chip 1

, must be a duff 4164 so replaced with another 4164, game now lives.

like a say not a hard fix, but that checkboard had me very worried to start with.

 

[Hurray Banana]

spoke too soon.

getting random ram errors st 3-1 and 3-2 tried swapping chips from working banks and still getting random errors. currently it's working.

I might replace some sockets

 

[Hurray Banana]

still crashing, obviously not faulty ram as I have swapped ram from different banks.

Replaced the two suspect sockets, not as quick to do as you might think, put in place two turned pin sockets, front ram chipped needed pushing home a little more.

broke a trace while doing this, it was a ground trace but had good ground connection from bottom of board (luckily)

fixed Rams in place and turned on, still getting Ram errors after a little while or if floor boards in playroom jiggled machine. Tested volts at ram chips, was getting 4.95V at Vcc.

Decided to pull Ram board again and have a look at the power connector pins. They looked pretty shocking

So Attempted to get rid of the messy solder and flux residue as best I could and re-soldered (ground pins on left were shocking - did my best)

Been on soak for 1 hour still fingers crossed working, I did check the pins on the rom board but they were ok.

Fingers crossed this is looking fixed.

I was gonna pull the power board but that looks like it had been rebuilt so leaving that for now. If I did ever rebuild this I'd probably look into doing a 5V adjustment pot at the same time.