(Topic ID: 274581)

System 9 CPU board row and column errors - Comet

By yaksplat

3 years ago



Topic Stats

  • 3 posts
  • 2 Pinsiders participating
  • Latest reply 3 years ago by yaksplat
  • No one calls this topic a favorite

You

Linked Games

Topic Gallery

View topic image gallery

pasted_image (resized).png
pasted_image (resized).png
pasted_image (resized).png
#1 3 years ago

So, yet again, I have an issue on my comet. I have a rottendog CPU in there that's working perfectly that I purchased, but when I put the regular board back in, i have a bunch of switch issues.
pasted_image (resized).pngpasted_image (resized).png
Any switch in Column 4, GRN-YEL, 1J8-4, will trigger the entire row

Any switch in Row 5, WHT-GRN, 1J10-5, will not work
Any switch in Row 6, WHT-BLU, 1J10-3, will not work
Any switch in Row 8, WHT-GRY, 1J10-1, will not work

Here are my thoughts. The column is U45 and possibly Q10, The rows are U52. That's from me just looking at the schematic and not being 100% sure. Anyone want to validate my thoughts or point me in the right direction?
pasted_image (resized).pngpasted_image (resized).png
pasted_image (resized).pngpasted_image (resized).png

#2 3 years ago

I would start with replacing U52.
The 4011 is a cheap part and known to fail if a problem occurs in the switch matrix.
Transistor Q10 is also a cheap part, so replace it too.
When this doesn't fix your problem, move to the U45.

1 week later
#3 3 years ago

That did it. Replaced U45 and U52 and the switch rows and columns work again.

Of course then I noticed that Lamp column 8 was out. Tried my hand at using a logic probe during the lamp test. U53 and U54 are both controlling the lights flashing, so I compared the two. Everything on U54 was working. All of the outputs on U53 were exactly the same as U54 according to the probe. I went on to comparing Q19 and Q22 then Q30 and Q27. That's where I heard and saw differences from the probe. I replaced Q19 and Q22 and lamp column 8 came back up as expected.

Promoted items from Pinside Marketplace and Pinside Shops!
$ 69.00
Gameroom - Decorations
Pinball Pimp
 
$ 1.00
Pinball Machine
Pinball Alley
 
$ 54.99
Cabinet - Shooter Rods
Lighted Pinball Mods
 
$ 36.95
Eproms
Pinballrom
 
$ 69.00
Gameroom - Decorations
Pinball Pimp
 
$ 18.95
Eproms
Pinballrom
 
3,450
Machine - For Sale
Ogden, UT
Hey modders!
Your shop name here

Reply

Wanna join the discussion? Please sign in to reply to this topic.

Hey there! Welcome to Pinside!

Donate to Pinside

Great to see you're enjoying Pinside! Did you know Pinside is able to run without any 3rd-party banners or ads, thanks to the support from our visitors? Please consider a donation to Pinside and get anext to your username to show for it! Or better yet, subscribe to Pinside+!


This page was printed from https://pinside.com/pinball/forum/topic/system-9-cpu-board-row-and-column-errors-comet and we tried optimising it for printing. Some page elements may have been deliberately hidden.

Scan the QR code on the left to jump to the URL this document was printed from.