Haha, good one Spyri....didn't I "invent" Restoreys LOOOOONG ago ?
Hey guys....I think I FINALLY found a problem that kept chasing my SW....
The thing was that after playing the game for about 20 minutes or so, the screen sometimes started to show what looked a bit like a sinus wave on the horizontal deflection. When played on, it got a bit worse apparently and the deflection spot killer kicked in (good to know that works !)...
It was only brief moments, picture would come go for a fraction of a second and be back for 4 or 10 seconds...
I first tried another game PCB set to make sure I was correct in my assumption that it was on the deflection board.
And indeed, the problem stayed.
So I started to closely examine the deflection board. Obviously, the issue was heat related because the problem only started after 20 minutes or so.
However, the fan that I installed does an EXCELLENT job on keeping everything cool, the difference is really huge, so I was a bit baffled that it still could be a heat issue, but localy of course, heat can still build up (a bit).
Now, I looked at the horizontal deflection section. SW owners know that this is on the upper section of the deflection board. In a cockpit, this is pretty close to the "lid" that is over it. Thus, this area is probably the hottest spot in the cab. (without the extra fan).
I started "feeling"/wiggeling at various compenents and looked CLOSELY what happened on the solder side. Very quickly I noticed that C11 had moving pins/soldering islands. Removed the old solder and resoldered it, fixed. So I started suspecting this area so I checked all components there an sure enough I find at least 4 other parts that have (slight) movement on the solderings. Fixed them all. Sometimes the islands had lifted because of the heat so I had to scrap a little off the track to solder it to that.
SO,I had good hopes, put it back in the machine for some more test-playing (oh what punishment !
) For a while I though I had fixed it, but after a while again the problem appeared.
So, while it was still running I watched the deflection board. Sure enough I could see the spot-killer LED go on every now and then. I was feeling/wiggling parts all over the horizontal deflection section to see if I had missed something. And YES, suddenly I found, that when I was pushing on Q14 (the small transistor on the big heat-sink at the top) the LED would go on, and when released it went out again. I could really turn it "on and off" by pushing straight on that transistor.
Took out the board, checked the solderings and sure enough there was a problem with one of the legs. The track had curled up a bit under it and it was making contact, normally, but when pushed the contact went open. So, had to scrape open some part of the track and soldered it to that, and also renewed the two other solderings.
Now, I am pretty confident that I fixed it, but it's long bed time here, so testing will be done tomorrow.