RE: Player 2, measure the 100k resistor at location resistor R3, likely it has gone high/open resistance.

RE: Player 3, this is a Stern display. A single bright digit is usually a shorted/stuck driver transistor/level shifter transistor. These are transistors Q4 and Q10 and/or shorted 100k resistor at R7.
There's also a number of suspect solder joints that need to be addressed/reflowed.

Display_SternHG1.jpg

Single flickering displays are usually cracked solder joints on the pin header and/or the glass display connector. The pin header looks to have been reflowed so check the soldering on the glass display pins.

If you mean the glossy brown stuff on the soldered pins, that's just flux/resin from the solder. No need to worry about it. If it aesthetically bothers you, use isopropyl to clean it with a tooth brush.

Flickering can also be due to bad pins inside the connector. Ask me how I know

That's an IDC (Insulation Displacement Connector). If you re-pin it you'll probably be using crimp on terminals like you used for the rectifier board.

Only difference will be instead of the loops you'll be inserting two wires into each pin

Check out this article- http://www.pinrepair.com/connect/#looped especially section #6 near the end.

Out of interest, do you remember which exact pin it was that caused the flickering?

Yep she's open resistance and needs to be replaced. Standard procedure says to replace all the six 100k resistors for the digit drive circuits. These are resistors R1, R3, R5, R7, R9 and R11. Technically they should be replaced with higher wattage resistors (1/2 watt).

What resistance do you measure across R1, R5, R7, R9 and R11?

RE: Player 3: set your meter to diode mode which is the ---|>|--- symbol.
The 1,000's digit drive transistors are Q4 and Q10.

The 100's digit drive transistors are Q3 and Q9.
The 10,000's digit drive transistors are Q5 and Q11.

These transistors all have three legs. With your meter in diode mode, check the readings between each pair of legs on Q4, and also do it with the meter leads swapped around (you should get 6 readings in total per transistor). Then do the same with Q10.

Now compare the readings of Q4 to both Q3 and Q5.
Do the same comparing the readings of Q10 to Q9 and Q11.
Look for anything abnormally different.
Q4 readings should be about the same as Q3 and Q5. Ditto for Q10 readings being about the same as Q9 and Q11.

What resistance do you measure across R1, R3, R5, R9 and R11?

Pin 20, the 5 volt pin on the display connector was busted

Hmm, strange. No voltage getting to the display decoder chip and I'd expect a blank display, not flickering. But the flickering is a common problem with cracked solder joints. I might have to test disconnecting that pin 20 here for my curiosity.

That pin was hanging on by a thread and intermittent. When I removed it from the connector it broke completely.
https://pinside.com/pinball/forum/topic/display-bright-dim-rolling

RE: Player 2: The only one of these resistors that's still in spec is R11. R9 is disturbingly low and will end up causing digit burn on the 10,000 digit. R3 open circuit is causing the blank 10's digit. All six of these resistors need to be replaced.

RE: Player 3: R3, R5, R7, R9 and R11 are all out of spec. Again, all six of these resistors should be replaced.
To be honest you should check these resistors on the other three displays.

Below are the transistor readings I've taken from one of my 6 digit displays. Is this roughly how you read yours? Note these readings were taken from the component side of the board.
First diagram is Q4 with all the combinations of legs and meter lead orientation.
First diagram is Q10 with all the combinations of legs and meter lead orientation.

Display_MPSA42_test.png
Display_2N5401_test.png

Post some clear high res pictures of the player 3 display from the component side - preferably outdoors in daylight but not in direct sunlight.

First, replace all those 100k resistors.
If the 1000's digit is still stuck on bright on the player 3 display and you're tired of taking transistor measurements, swap Q10 for Q7. If no change to the stuck digit position then swap Q4 for Q1.

Brush clean the top of that board to get all the dust and crap off it.
I don't see anything obvious other than it's been sitting in less than ideal conditions for a long time.

Nope, those are the wrong resistors.

These are similar to what I use. Looks like you get them for AU$4.80 per 100 pack delivered the next business day for free.
https://au.rs-online.com/web/p/through-hole-fixed-resistors/1711691/

These guys may be local to you and have all the parts:
https://www.rockby.com.au/CatresultsSql_12.cfm?Searchkey=100k&stock_no=34908
https://www.rockby.com.au/CatresultsSql_12.cfm?Searchkey=2N5401&stock_no=10795
https://www.rockby.com.au/CatresultsSql_12.cfm?Searchkey=MPSA42&stock_no=17322

Your transistor readings don't show any obvious short circuits. But one of them could be failing under load.

On player 3, are you able to swap Q10 with Q12 and Q4 with Q6? This will move the digit drive transistors from the 100,000 digit to the 1,000 digit.

Q4 is the same as Q6
Q10 is the same as Q12
Q4/Q6 are NOT the same as Q10/Q12 so don't mix them up.

If you're ordering transistors with the resistors then just swap for new since they only cost pennies.
If he's a friend that can quickly just swap the current transistors around mentioned in post #21 while you wait for parts, you'll find out if they need replacing.
Don't forget to get all the cracked solder joints redone.

I don't have anything to add to this, other than saying Quench is a rock star!

Carry on.