JD Lamp matrix issues

[orchid]

Hi all,

So, I bought a JD in need of a bit of repair. One of the main things I've found to be not working is row 8 on the lamp matrix. Nothing on there lights. The relevant transistor at Q83 seems fine. Is it likely to be a broken wire, and is there any way of checking before tracing it all the way through the machine? The only lamp that does light in row 8 is Supergame (#38), which light with anything else on Col 2 to varying degrees.

The other lamp issue is that in nearly every row, column 7 also lights column 8 (e.g. J in JUDGE is lighting Award Stakeout (Row 1, Col 7 & 8).

Haven't dealt with matrix issues before - what should I look into?

Thanks

 

[Spandangler]

It's probably the connector mate, look for a toasty connector on the board, or dry solder on the header pins if not could be a wire off somewhere like you say.

 

[orchid]

I got around to looking into this again yesterday in a bit more depth - doesn't seem like there's any bad connectors that I can see. I managed to stop the lamps lighting together by removing a connector J136 (which I found from the manual isn't actually supposed to have anything connected).

Still, row 8 is completely out. I did a pretty thorough trace through and it seems like the cabinet lamps are the issue (Start and Supergame) - those are the only ones that don't beep out in connection with the other row 8 lamps. I was a bit confused by what looked like a hack-job on the Supergame wiring (photo here), so I removed both the diodes (one on switch, one on lamp) that were directly attached to the button housing (as neither the Start nor Extra Ball buttons on the cabinet had diodes - they're separately on coin door interface board I think?). That made Supergame light when the game came on, but not when it was specifically triggered through test mode, so I put the diode back. Did seem to indicate that power was getting to it fine though, which confused the issue of there being a circuit break somewhere.

Finally, I also went through the lamp rows on the driver board using a lamp socket and a 1N4004 diode from J137 to each row on J133 - for some reason (and I think I had the diode the right way round), the lamp wouldn't light, but lit up fine on each row once I took out the diode. Except row 8 - which wouldn't light. This leads me back to thinking it could be something on the board, but as I say Q83 seems fine (which I tested again).

What should I try next?

 

[pinballmania]

Reseat the short ribbon cable and press home the ASIC chip on the CPU. After that its time to get the logic probe out and analyse the path to the transistor.

In all lamp test, you can unplug a row or column connector, then use one end of the connector and use it to probe each output on the header. The same group of lights will flash for each pin tested.

 

[orchid]

Thanks - is a logic probe pretty essential?

 

[orchid]

Argh - just tried to lift the ASIC chip a bit to reseat, and now the DMD is behaving very strangely. Uh oh...

edit: Fixed by pressing chip back in (phew!) - but now it's resetting date/time/scores at every boot...
edit 2: Fixed resets by time-honoured method of 'the wiggle'. Was really worried there after having googled 'replace ASIC socket' - looked like a right ballache!

 

[Spandangler]

Just keep reseatting that ribbon connector. It'll sort itself out. My FT had reset problem. So I reseated the ribbon connector and pressed that chip and the DMD scrambled and I lost half the GI and solonoids. After a few reseats, everything came back

 

[orchid]

Yup, fixed that now thanks - back to the original lamp row 8 issue now.

 

[Sgt GrizZ]

Sometime ago had similar on Dave Roberts Roadshow - I remember the cure was replacing one of the chips on the CPU ...can't remember which one. U10 maybe ???? I'm not saying that is the yr culprit ....but after everything else checked out - it was a chip issue. Sorry for vagueness :rolleyez: