Blackout has display issues for the first time. I've had the machine for 4+ years, and I've turned it on 100+ times and never saw this issue until recently. I am a beginner at troubleshooting display issues, so please guide my troubleshooting from the ground up, even if you have a strong suspicion as to what the cause is. I like to learn the best practices approach to testing things one by one - I'm not in any hurry. When I play a match, the few digits that work in player-1 do keep score. Thank you!

Symptoms: These digits are out:
player1: 100k, , , 10 ,
player2: 100k, 1000, , 10 ,
player3: 100k, , , 10 ,
player4: 100k, 1000, , 10 ,

credits: (forgot what this display is called)
10
10

So, to recap:
100K is out in all 4
1000 is out in only player 2 and player 4
10 is out in all 4 + the two from the credits display

Also -- it looks like a few 0s are 8s. I would think to address that last, but perhaps it is related.

WHAT I'VE TRIED
1. tested connector input power to master display for -100, 5, 100, gnd -- checks out ok
2. reseated connectors to master display (no change or flickering while reseating) -- checks out ok
3. with power off, tested resistance to two sets of resistors and saw equal values across the board -- checks out ok
4. with power off, did the ohms test (per pinwiki) on IC 1,2,3,4 and 11, 12, 13, 14 on the legs, and didn't see any odd values other than IC1, leg9 is a tad high (.920) when all legs are measuring .662 or .866 with power off, and 4J removed. -- checks out ok (mostly)
5. reflowed headers on mpu to display 1J3, 1J4, 1J5, 1J6, 1J7
6. swapped MPU and the problem is solved, so we know 100% it's on the mpu. So the old mpu is back in there to investigate further.

RESOURCES:
I have a firepower system6 with xpin displays and a rottendog board.
https://www.pinwiki.com/wiki/index.php?title=Williams_System_3_-_7
Firepower schematics

ALSO WONKY
A few sounds are not playing properly, but most do.

https://pinside.com/pinball/forum/topic/resto-blackout-mof-20180225/ (original resto thread)
blackout-digits-missing (resized).jpg

Did not see a change while unseating and reseating top connectors on mpu. Luckily, I have a mirror in the garage, and was able to see the displays on the wall while working.

1J5, 1J6, 1J7

I just replaced the mpu from another machine. It's isolated to mpu 100%

First time user of the strobe tool.
According to the strobe map -- the ones that strobe "high" are the ones that are broken. The ones giving me "high+low" (which I presume means a good square wave of 5 and 0?) are all the working digits (minus pin 12, which appears to be the expected result.)

Thanks, I'm ordering a socket and I appear to have the chip on hand -- I should have this fixed up in a week or so when all parts arrive, we'll see !
-mof

I'd be done today -- but my 2013 Hakko 808 desoldering gun has a broken heating element. I took it apart and took a look in there -- The dang wires lost their bond to the element !?!?

How long should a heating element hold its bonds to the wire? I couldn't have used that thing for more than 120-180 minutes of use over the years, and it never fell off the table.

=(

-mof

Good news. bad news.

1. Good news. Got a new heating element shipped out in only 4 business days for $70, and it works! Feels like it was an original part from hakko as well. The attachments from the wires to the heating element are white not silver, I hope that's an upgrade that will last for more than a few hours of operation.

2. Bad news. I got the old IC6 chip out. I installed a 24-pin socket. I continuity tested all the leads to all the resistors. I checked against continuity between legs. I inserted the new chip. I tested from chip to resistors. It all added up to a win. But this is pinball.

Turned on the machine, and got a middle finger. One 8 staring at me. Tested with strobe, and all legs are high or low now.

I'm guessing it's just a "wrong chip". Here's what I had and what I installed. Could just be operator error!

Now that I look closer -- I'm thinking this is a lamp driver chip. Doh.

I see some chip discussion here:
https://pinside.com/pinball/forum/topic/substitue-for-ic-74154

-mof

Trying to figure this out...

Bally E-00620-0037 = lamp driver board part https://www.actionpinball.com/parts.php?item=14514
or do I want...
Bally E-00620-0039 = looking like the one I want. https://www.marcospecialties.com/pinball-parts/74154

Yep it's the wrong chip !!!

amirite?
20220615_8-with-bad-strobing (resized).jpg4514 (resized).jpg

New chip arrives Saturday hopefully.
-mof

The new chip is in !!!

new-chip-no-change (resized).jpg

Pins
1,5,7,9,11
14,16 are HIGH. (Strobe 13, 15)

https://pinside.com/pinball/forum/topic/williams-system-3-6-display-problemseeking-help

Is suggesting I check between IC18 and IC6. Let me go see what I find.

yes

2,3,4,5 on IC18 all pulse hi-lo to 20, 21, 23, 23 on IC6

What's the next thing I could try?

Even though a full rottendog proved it was 100% mpu/driver, are you saying - divide the old board set in half, and just rule out driver board by swapping another one in there?

The only driver board I have on hand is a system7 for cosmic gunfight...

My only other system6 -- firepower, is running a Rottendog...

For the purpose of isolating the driver board -- can I expect ok results from swapping a system7 driver board in there?

-mof

Before I swap the driver board out -- I was wondering -- can I get "misleading" readings from my strobe tool? In that -- does it have to be a pure 5/0 signal? What if it's 3v and 0v?

I decided to check all TPs on the MPU first:

1) 12 ,12v unreg
2) 3.93 ,nmi <=== ?
3) 3.9 ,mem protect <=== ?
4) 4.72 ,blanking
5) 4.83 ,irq
6) 2.45 ,bus 02
7) 4.93 ,cmos ram
8.) 4.90 ,reset
9) 5.0 ,input
10) ground ,ground

Are nmi and mem protect a lil low?

It is the driver board indeed !

I just added to the main post: something which may help us narrow things down on the driver board:

ALSO WONKY
A few sounds are not playing properly, but most do.

update: including no speech.

Examining the driver board, I see some work has been done.
Can anyone make sense of this work?
All these wires feel firm to the touch like they haven't moved.

What the heck is going on, and how did this work for a few years?

20220617_212137 (resized).jpg

20220617_212252 (resized).jpg

20220617_233027 (resized).jpg

20220617_233043 (resized).jpg

20220617_233109 (resized).jpg

20220617_233206 (resized).jpg

20220617_233402 (resized).jpg

20220617_233506 (resized).jpg

Thank you -- can you share with us how you came to figure out this is the culprit?

Is the sound clue any help?

I'm still hoping to learn what the heck all those chip mods are that were done on this board.

Yikes.

https://pinside.com/pinball/forum/topic/where-to-get-6821-chip-and-socket

40-pin sockets arrive Tuesday likely.

Testing pulses on ic10. Pins 38 and 34 are high.
Normal?

I'm doing research looking for ideas on how to test the PIAs. I see one I can try.

https://pinside.com/pinball/forum/topic/alien-poker-stuck-solenoid-pin-1-ic6-7408-high-where-to-trace-now#post-674188

Chris suggests:

In my case
IC11, 18: LO
IC5, 39: HI
IC10, 19: HI <-- not the oddball

I tried those three spots on a working driver board and they measured the same. So perhaps I'm not seeing how this exercise works.

I guess my case is awfully similar to: https://pinside.com/pinball/forum/topic/williams-system-6-display-issues-

But I'd still like to learn more about how IC10 tends to be the culprit and what to measure to prove it.

I'll see what I can pick up from this Clay video

thanks.

Are there any tests I can run (with no special roms to help) to verify it's IC10?

MARKING THIS THREAD GREEN CHECKMARK

Thank you all for the help.

PIA III - Lamp Matrix - IC10 it is.

My sounds are still a tad wonky - no voice and a few sounds are off. I'll regroup and open a new thread on that when I get the nerve up to chase that one down. Bad displays was a much bigger black eye on the game.

-mof

Question: Should I replace all those oddly manipulated 7408s? Or just leave 'em ?

Just more bread crumbs for the next adventurer:

I was emailed this bit of specific advice:

When a PIA quits, it normally locks up the game, but in real life PIA's can do that or, just partially fail:
1. If A lamp PIA is removed from a working game, the displays will be showing the same problem (every other lit) -- The software just needs to see the lamp PIA
2. The lamps can still operate with a faulty lamp PIA and cause the display problem.
3. The solenoid PIA and Switch PIA (if unplugged) -- the displays will be fine.