HP-34C display malfunction, need help



#2

I have an HP-34C, and rebuilt it yesterday to make sure
that there are not loose inner contacts (this is the unsoldered spice series).

Even so, THE DISPLAY DOESN'T BLANK PROPERLY.
Example, if you type in Sin(45) .
You can see it calculating for a few seconds while
it calculates. the result is correct.
It even passes its self test 8,8,8,8,8,8,8,8,8

Let's say you just start entering a number:
2.22222222
Each time you type that "2", the whole display
blinks in an unpleasant way.
The "-" and all the commas light up.

Reminds me of things that maybe an HP-25C
might do, they would show comma activity, if I recall.
Luiz states that many of the SPICE series do what I am saying, but his sample of the 34C does not, and I never saw any HP-34C specimen do that before.

So three questions:

Did anybody see early versions of the 34C actually do this by design ?
Did anybody see a unit degrade into this condition ?

Did anybody figure out a way to fix it, for example,
whether the big chip, or the power supply is to blame ?

If U tell me what the problem is, of course, I will fix it. Cosmetically, the unit is clean as new and worth trying to save.

- Norm


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