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Re: DC508A Display

 

It is certainly possible for a 7447 or any TTL IC that old to fail. On
my SG503, one of the 7475 latches feeding the 7447 failed. I would
expect 7447s to actually fail more often since they have to operate as
a driver and often run hot.

I would actually suspect bad Texas Instruments sockets first but I
know some of the LED displays in this modules had poor reliability
which is apparently not the issue you are having.

On 26 Mar 2016 19:16:59 -0700, you wrote:

Hi -
I know the DC508 display is a common point of failure, and that Paul Read even offered replacement display boards at one point (Paul, do you still have any?).
I'm wondering if anyone has had a failure mode that wasn't the display itself, but the 7447 instead? In my case, I'm not missing any elements, but certain numbers are malformed, and the same number is malformed in each digit. Does a bum 7447 sound plausible? How do these displays usually fail?
thanks!
Paul
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