Some people should NOT handle schematics, soldering irons etc.
Now that I got THAT out of the way, seeing as how I should have posted this BEFORE I thought I could find my own problem...
Please stick with me, this one has a little lengthy explanation.
I'm trying to trouble shoot the very list issue on my Laser Ball, the lady's hand flashing lamps (type 89 bulbs) remain lit and they have since I acquired the machine, I noticed early on the two large resistors on the back of the light board were toast so I replaced them long ago, didn't worry much at the time as the machine was undergoing my scalpel.
So fast forward, and fearing the logic probe (God knows why, I've read the @terryb guide many times) I started off replacing Q42 and Q43 as I interpret the schematic to indicate it is this solenoid drive that controls these (schematics pgs 4 & 17.) I DID check these with my DMM prior to replacement and while they did test GOOD, I've seen anomalies before where a transistor or SCR tested fine but in operation they fail. SO, I replaced Q42 and Q43, no change, the type 89 lights stay lit constantly (LEDs I did not think to try incandescent).
This is where I made an ass out of me and the umption... I examined the schematic a little better (page 5, sheet 1 of 2), looked like perhaps the blanking circuit was a possible culprit. After all it has a signal line into IC4? I Found Q76 and Q77 might be to blame, and the other part of the umption, not having the EXACT required components (2N6427 - 40V/0.5A nor a TIP42 - 40V/6A, again BOTH originals TESTED FINE) I dropped in an BC32740BU - 45V/0.8A and TIP102G - 100V/8A respectfully, and FAILING to notice the BC32740BU was an E B C configuration, and not an C B E, turned machine on and while there was no change to the type 89 bulbs that SHOULD be controlled by Q43 I took note that now ALL player lamps are illuminated, the SAME PLAYER SHOOTS AGAIN lamp is illuminated, TILT was on and maybe others, just can't recall, it was now 0000 hours and I would get up this morning at 0400 and try again.
While "technically" there was no smoke, no faint smell of ozone (sorry if my title mislead you), as my pappy used to say, the dog don't hunt. It turn on, but won't operate. It had been able to start a game an launch the ball but now won't do even that. I had traced with my DMM continuity as best as I could determine and found all traces intact that I tested.
Schematics at the ready, order pending for silicone components, half way decent pictures of I'm just at work and not home to test / report results.
Pictures now show a missing IC13, as I intended to removed IC14 but on less than 4 hours sleep, I do have sockets and replacement 7408 chips to replace BOTH these today after work. Damn work getting in the way of a hobby.
As the prosecuting attorney now says, is there a question anywhere in the future,
I beg the jury, what could I have fouled up, suggestions for remedy?
And with that I throw myself to the mercy of Pinside...