BK80: T'shooting Wonky Lamp Behavior

[lothian]

Black Knight (1980)

I'm working my way through a list of issues with my Black Knight. The thing suffers from some kind of attract mode lamp display problem that seems to affect the "sword" lamps in particular. The sword lamps seem to operate normally during game play mode, btw.

The video below illustrates the problem. It's a side-by-side comparison between my machine (on the left) and a machine with a normal display.

The BK80 uses a lamp matrix. I've read two articles that describe the theory of operation. Does the video of the attract mode on my machine indicate a problematic diode... or something wrong in the matrix? ...or some other thing entirely?

Opinions, suggestions, recommendations welcome.

 

[necro_nemesis]

Could be a simple as a bad lamp diode. You might count up the funky ones and see if there's a common column or row. Could be a wonky 6821 PIA for the lamp matrix on the driver board. If they've been worked on and socketed it may be worth plugging in another lamp matrix PIA and see if the problem persists.

Quite frankly it could be a number of things but my guess is based on what typically will pack it in.

Edit. This is the System 7 troubleshooting guide I found most useful to me in the past. http://pinball.flippers.info/system6repairpart5.asp

That and burning myself a copy of Leon Borre's test chip to pulse outputs.

 

[necro_nemesis]

Leon Borre WMS System 7 Repair - PinWiki

www.pinwiki.com

Apparently the file to burn his EPROM on a 2532 is here long after sadly he is not.

Here's another tool for the toolbox that can test the lamp matrix isolated to the board.

Lamp Matrix Tester Board - Siegecraft Electronics

Lamp matrix simulator board. These simulate the playfield lamp matrix using a toolbox friendly 8x8 LED matrix, allowing you to quickly isolate a controlled lamp problem. Compatible with Williams System 3 through to WPC-95, Data East. Limited compatibility with Sega/Stern 'Whitestar' and SAM...

www.siegecraft.us

 

[necro_nemesis]

I have PIA's and can burn ROMs but Dave Astill on here does and sells them as a service. I suggest if you are looking for these items he'd be the go to guy.

 

[Pinguylondon]

I had this issue with one of my Black knights, I had 1 bad diode in the lamp matrix and a bad chip on the driver board. Once both were replaced, never had another issue.

 

[lothian]

Inspired by this article and this video, I bought a Lamp Matrix Tester Board to assist me in t'shooting the aforementioned problem(s).

I'll post a follow-up after I've done the deed.