Re: Gorgar (Sys 6) display problems

Thanks for all the replies.

Replacing the 74154 solved my missing digits problem, but I still have the
missing segment problem. I did resolder all the pins on the MPU, but that
didn't help with the segment issue.

Where do I look next?

Herb Schanke

"Chester Pete" <pREMOVEfmatthews@xxxxxxx> wrote in message
news:dtvkts$m82$1$8302bc10@xxxxxxxxxxxxxxxxxxx
Hi there,
I'm pretty sure its the 74154. It sounds like one of the "strobes" has
gone. I fixed a similar problem on a system7 only a few weeks ago.
The reason for this is that the same digits are missing on displays 1 and
3.
1 and 3 displays use the same strobe lines
2 and 4 dispays use the same strobe lines.

good luck



"Herb Schanke" <hschanke@xxxxxxxxxxxxx> wrote in message
news:1141062842.286658.29900@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
I've got two problems with the displays on my Gorgar. I've tested
the master display board in another Gorgar and it works fine. I've
checked the wiring from the MPU to the master display and it all seems
to be OK also, so they would appear to be MPU related

Problem #1: I'm missing to two rightmost digits (ones and tens) on
the displays for player 1, player 3, and the credit/ball display.

Problem #2: Segment "e" (lower left) is missing for player 3 and
player 4.

I haven't pulled the MPU, but the first thing I'll check is the
connectors and pins, but assuming they are good, what's a likely next
step?? I'm thinking of replacing the 74154 decoder and/or the 6820
PIA, not because I have a clue what they do, but just because they're
the next component upstream from the connector (other than resistors).

Anyone have any better suggestions how to attack these problems?

Thanks,

Herb Schanke





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