(Topic ID: 275057)

Newbie needing help with a board issue

By LaverniousJames

3 years ago

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9 posts
6 Pinsiders participating
Latest reply 3 years ago by Billc479
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Black Knight Williams, 1980

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Hi there!

I just recently picked up a Black Knight project for very cheap, and I have run into a problem almost immediately. (I did buy this knowing that it didn't function, so it wasn't from when I moved it home.

The Black Knight is an earlier one, with a System 6 power supply and transformer in the backbox, as opposed to the later ones where it's in the cabinet.

When I got the machine home and set it all back up, I noticed that the man I had bought it from had the wrong fuse in almost every slot. I have replaced every fuse but 3 (the one on the playfield and the two on the soundboard) hoping that it would cause some change, but nothing happened. The problem I am having is that the cpu board seems to be locking up, and I get no function from the displays at all. I have tried reseating all of the connectors, and reconnecting all of the connectors running from the cabinet to the boards, but to no avail. All I am getting any time I turn the game on is a loud speaker hum, some of the general illumination lighting, and the 0 display on the cpu board. I am not sure where to go from here.

I have attached a few photos of the displays not working and the cpu board showing the 0 on it's display as well as some photos of the driver board of components I'm not well versed enough in to know if they might be a problem. I would like to try to get these boards working again, but if I do need to get new boards, that isn't out of the question either.

The man I bought it from said that he had done some repair work on the power supply and removed some bridging, but it was so long ago that I am not sure what the bridges were to or for.

I would really appreciate some guidance from anyone on here who might know where I should start with this thing. Thank you for helping someone who desperately wants to learn how to fix these things, but is too new to figure it out by themselves.

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First, welcome to the world of hybrid system 6/7.

Second, if you don't already, get a multimeter and learn how to use it. Check your voltages at the test points on the power board and on the MPU . (The board with the batteries.) Third, your board is locked up - refer to the tag on the left of the MPU. Fourth - replace the RAM with NVRam, which will eliminate the batteries.

It looks like your 40 pin connector is original - both sides should be replaced for reliability. If you don't have the experience and tools to do that, send the boards out for refurbishment and repairs. (You have a few gnarly looking drive transistors soldered in place). If you send the board out for repairs, have them replace the RAM with NVRAM. (Chris Hibler, or others are on this site and do this type of work)

Keep in mind, getting the power supply verified good and the MPU/driver board set working may not be the only issue, but at least you can eliminate those as a problem.

Also, check Pinwiki for Wms system 6/7 troubleshooting and repairs.

Keep us informed.

Pinwiki is a great place to start. https://www.pinwiki.com/wiki/index.php?title=Williams_System_3_-_7
Checking the voltage at the test points will help us help you narrow down the issue.

Congratulations on the new machine! Looks like original, unmolested boards in that machine!

0 on the LED display means the CPU is not starting at all. Can be caused by a myriad of things.

You can start by reseating each of the ROM chips.

It looks like you have an AMI brand CPU chip which is a notoriously suspect manufacturer if indeed that is a 6808 CPU in the socket. I would start by replacing that chip since it is socketed. You could borrow the CPU chip from the sound card as long as it is a 6808 and not also an AMI brand chip.

Some good reading on the steps needed to bullet proof your boards. https://pinside.com/pinball/forum/topic/vids-guide-to-bulletproofing-williams-system-6/page/18#post-5597994

a solid 0 on the led might mean you are missing your 12 volts....a buzz makes me suspect the big cap on the power board. a 0 could also mean no program but my hunch is you are missing your 12v unregulated....it is a common problem in older williams games. the 0 basically means your cpu board hasn't started, which could could be a few things but again I'm betting it is a power problem....

Quoted from Billc479:
First, welcome to the world of hybrid system 6/7.
Second, if you don't already, get a multimeter and learn how to use it. Check your voltages at the test points on the power board and on the MPU . (The board with the batteries.) Third, your board is locked up - refer to the tag on the left of the MPU. Fourth - replace the RAM with NVRam, which will eliminate the batteries.
It looks like your 40 pin connector is original - both sides should be replaced for reliability. If you don't have the experience and tools to do that, send the boards out for refurbishment and repairs. (You have a few gnarly looking drive transistors soldered in place). If you send the board out for repairs, have them replace the RAM with NVRAM. (Chris Hibler, or others are on this site and do this type of work)
Keep in mind, getting the power supply verified good and the MPU/driver board set working may not be the only issue, but at least you can eliminate those as a problem.
Also, check Pinwiki for Wms system 6/7 troubleshooting and repairs.
Keep us informed.

Thank you for taking the time to respond! I've picked up a multimeter and as soon as I have some time off, I'll work on testing all the voltages and see if anything is off. I don't have a lot of experience in dealing with soldering and replacing components, but I do have a little. Thank you for giving me the name of someone who can fix these boards if I en up screwing up/unable to do it.

Quoted from YeOldPinPlayer:
Pinwiki is a great place to start. https://www.pinwiki.com/wiki/index.php?title=Williams_System_3_-_7
Checking the voltage at the test points will help us help you narrow down the issue.

Thank you! I will check the voltages when I have a day off and get back to you all with results.

Quoted from Atari_Daze:
If you need a manual:
https://www.ipdb.org/files/310/Williams_1980_Black_Knight_English_Manual_with_paginated_schematics.pdf

Thank you! It did come with it's physical manual, but having that digital one is handy.

Quoted from Schwaggs:
Congratulations on the new machine! Looks like original, unmolested boards in that machine!
0 on the LED display means the CPU is not starting at all. Can be caused by a myriad of things.
You can start by reseating each of the ROM chips.
It looks like you have an AMI brand CPU chip which is a notoriously suspect manufacturer if indeed that is a 6808 CPU in the socket. I would start by replacing that chip since it is socketed. You could borrow the CPU chip from the sound card as long as it is a 6808 and not also an AMI brand chip.
Some good reading on the steps needed to bullet proof your boards. https://pinside.com/pinball/forum/topic/vids-guide-to-bulletproofing-williams-system-6/page/18#post-5597994

Thanks for responding! I'll definitely be reseating all the rom chips next time I can dedicate some time to doing so. Also, I didn't think of the CPU being bad, that's definitely a possibility that I'll keep in mind!

Quoted from Startek2:
a solid 0 on the led might mean you are missing your 12 volts....a buzz makes me suspect the big cap on the power board. a 0 could also mean no program but my hunch is you are missing your 12v unregulated....it is a common problem in older williams games. the 0 basically means your cpu board hasn't started, which could could be a few things but again I'm betting it is a power problem....

Excellent! I will check for that, thank you. I have also ordered a power supply cap rebuild kit, just to be doubly safe.

Seriously, thank you everyone who has stopped in to offer some wisdom, I'm really looking forward to working on this.

Hello again.

I finally had some time to do a bit of work on the game, so I pulled the power supply board out to get a better look at it.

I was greeted with a pretty rough looking backside of the board.

The guy I got it from mentioned that there were jumpers on the board before. Does anything here scream: "I need a jumper" ?

I intend to clean up the soldering job that was done, but figured that I'd post photos here to see if anyone sees any red flags.

Thanks you!

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It looks like all of the “large” joints are cold joints, the edge connector joints look like the solder was blobbed on, and if they are through holes(runs on both sides of the circuit board) then likely poor connections to the component side runs.

All the joints need the flux removed.

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