Black Knight

[ChadTower]

Closer inspection of the drop target coils shows that coil 2 fires in test but does not fire with enough force to reset the bank.  It does not appear to be mechanically restricted and is firing with a lot less force than the two good ones.  This is the lower left bank.

The length of time a coil is "pulsed" in diagnostics may not be long enough to make the device "dance". That is for example, in game mode, it takes a fairly long pulse to reset a drop target bank. But in diagnostics, usually shorter pulses are used. So if that drop target bank does not reset in diagnostic mode, don't worry about! Wait until game play and test the coil there before working on something that isn't really broken.

Remind me to buy more TOP videos in the near future to support this guy a little more.

The lower right bank coil 3 does not fire at all.  That is the one failure I'm getting in individual coil tests.

Still need to track this one down.

[ChadTower]

Note:  coil 2 has a different third party looking label with a different part number.  Probably why it is weaker.

The good bank coils measure 3.7 and 4.1 ohms.  Coil 2 and coil 3 are both 4-5 ohms.  The coils are okay. 

[ChadTower]

All four bank coils have ~31v DC on both legs.  

My son just asked me if I put in the rest of the new ROMs yet.     I haven't. 

[ChadTower]

Game and flipper roms replaced, no change.

Coil ground shorted to siderail, it fires just fine.


EDIT:  Calling it a night.  Wiring checks out okay on it.  Next to check is transistor and header.  I'm betting on cracked header...

[shardian]

Short the driver transistor tab to ground and see if the coil resets.

[ChadTower]

Definitely.  Manual says the two drivers are Q9 and Q19.  Could be either, I guess, since Q19 is matrixed to one of the unused coils so there isn't a second dead coil to point it out.

[ChadTower]

Q19, definitely bad.  So are two of the three resistors right above it.  Interestingly, I found a broken off resistor a few spaces away, and didn't get anything in test that would indicate a problem on that coil...

...anyway, I have a TIP120 on hand but not the right resistors.  So I'll have to see if Rat Shack has them otherwise it's a weekend trip to You Do It.

[ChadTower]

Heh.  On boards I don't want as keepers I'd do that.  I'd rather just hold off a bit and use the right parts on a full project, though.  Looking back I would have been better off swapping boardsets with the Laser Cue and doing the upgrades on that one.  I had totally forgotten how clean that boardset is until I pulled the sound board the other day.

I cut out the 2N440 above that transistor too.  There is some burn damage to the PCB under the TIP20 that you couldn't see with it folded down.  I had rebuilt an iffy trace repair on the backside of this transistor already and forgotten.  I think I'm going to run a couple short wire jumpers here for the other traces off this transistor just to be sure they aren't going to fry when I run current through it again.  They are beeping out but are burned right off the board.  I might have to use a dab of glue on the topside to secure the TIP20 in place, too.  

BTW, I know I go way too far into the details in these threads.  I do that because these are my project notes.  I work on these things in 20-30 minute intervals that aren't always close together.  If I don't keep notes like this I spend too much time trying to remember exactly what needed to be done next.

[shardian]

BTW, I know I go way too far into the details in these threads.  I do that because these are my project notes.  I work on these things in 20-30 minute intervals that aren't always close together.  If I don't keep notes like this I spend too much time trying to remember exactly what needed to be done next.

I do the same thing. It is nice to have a time-stamped log of what all you have done. My wife thinks I'm silly that I'll do troubleshooting for a bit then immediately get on the pc to type out my results and thoughts.

[ChadTower]

It was really helpful in the Tank II thread.  I got a lot of great feedback and probably wouldn't have figured out the monitor brightness issue otherwise.

[ChadTower]

Replaced Q19, the predriver right above it, and the two resistors above that.  They all looked questionable.  The traces on the backside were intact but toasted off the board so I used a cut resistor leg to jump a really short one and some wire to jump the long one.  They beep out much stronger now...

...but more importantly coil 3 fires nicely now.     All coils pass, all sounds pass, lights look as good as old bulbs will, and when I manually reset the drop banks all switches pass.  Looks like I'm ready to tackle the upper playfield soon. 

I also got the 5101 issue fixed.  Turns out it wasn't the 5101 at all.  The new batteries leaked.  Let's hear it for the off board battery holder mod!  That just saved me a bunch of hassle.   

[ChadTower]

That thought did occur to me.  What's weird is it was the middle battery only.  I'm sure I'll have to pull the CPU again sooner than later for some reason.  When I do I'll just swap that out even if it tests good.  It's a 60 second job.

[Q*Bert_OP]

If anyone in here gets their ball trough plated they deserve to be kicked in the nuts.

 

Warn me before you come to Corpus...I'll have to protect my ball trough

I even sent the prop stick off to be plated on my Xenon restoration...

[ChadTower]

Put the top of the playfield back together, mostly shopped on top, so we could put some test games on it.  Plus we want to play it.

Won't register end of ball -> none of the trough switches are working -> trace the line to the scoring switches on the kickers -> lower playfield turnaround -> lower playfield eject.  That's the whole green-orange line in the switch matrix.


EDIT:  traced it back to the driver board connector, if I hold down one of the switches and wiggle the connector, the switch starts working.  It's either a cold joint on the header or a bad pin on the connector or both.  Headers were all reflowed when I did the driver board so I'm betting on the connector.  IDC sucks anyway - I have the parts to replace.

[ChadTower]

I have pulled it a lot of times lately while working on the boards.  Guess that got this pin... may as well do the whole connector to be sure.

[ChadTower]

Replaced offending header and connector.  Now all of the switches in that string work except 18 - center trough switch.

The other wire on that one is white-red on a different connector...    Hopefully it just needs a cleaning.

Gah...

Incorrectly Assembled Factory Switches.
Part of the problem Williams was having with switches was due to an assembly mistake, which started in the mid-1970s (pre-solidstate). It turns out Williams was assembling one of the pair of leaf blades backwards. This was not a huge deal with Electro-Mechanical (EM) games, but with solidstate games, it was a BIG problem. Because solidstate games use low voltage (5 volt) switches (unlike EM games in which all switches were high voltage 28 volts), the contact rivets are gold plated to help keep them clean (gold is a non-corrosive metal). But because one of the switch blades was reversed, a gold plated switch rivet made contact with a gnarley rough non-gold plated switch rivt.

Problems occurred mainly with any switch where a ball "sat", like the ball trough, lock or kickout holes. This mistake was not realized until the Firepower era, and Williams offered retrofit kits for Firepower and Black Knight ball troughs using microswitches to fix the problem. Note an improperly assembled leaf switch can be taken apart, spliting the bakelit "switch stack", and turning around the incorrectly assembled leaf blade.

This game seems to be riddled with switches where the gold pad is on the outside of the switch... I might have to address that during the swap.  I'll think about it.

[ChadTower]

Getting closer... cleaned switch 18 and it registers in switch test now.  Unfortunately when I play a ball it still doesn't register drains.  All trough switches work in test so I guess next is to play around with them in play mode and see if they are all working in actual use.

EDIT: meh, apparently there are more problems than this in play.  It's talking but no game sounds.  Balls not ending.  Two captured balls doesn't kick a third... etc etc.

[ChadTower]

Sound Board Test Works, but Missing Sound in Game.
Sometimes there will be a problem where the game is powered on, sound test button pressed, and all the sounds (and speech) work. But in game mode the sounds don't work. Usually this is a 6821 sound board PIA problem, or maybe a 6810 problem. But here's some things to try:

    * Verify with a logic probe that the 5 signal lines to the sound board are all pulsing low when cycling through solenoid tests 9-13.
    * Grounded each signal pin at the sound board and see if sounds are produced.
    * Measure the associated pins on the 6821 when you're grounding pins on the sound board connector pins.
    * Check sound board IC6 pin 13 (4068). It should pulse high whenever you ground a pins on the input connector.
    * Check sound board chip 6821 pins 37/38. If it's working, the /IRQ will go low when you ground input pins.

So at least that's the next steps.  Haven't used a logic probe yet but I'm about at that level of troubleshooting now, I think.