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Some HP parts inside
11-16-2016, 07:54 PM
Post: #1
Some HP parts inside
Hello!

Recently I found this piece here missing from my collection (Aristo Unilog, ca. 1975 - non RPN...):

[Image: IMG13275_crop_picc.jpg]

Unfortunately it does not work, even after replacing the slightly corroded battery connector. When moving the I/O switch, some digits of the display flash briefly, but this is all.

But inside, there is a display from HP, something that I don't see very often in non-HP calculators:

[Image: IMG13272_1024px.jpg]

[Image: IMG13273_1024px.jpg]

and some creative soldering as well (I have no idea what that potentiometer is needed for):

[Image: IMG13274_1024px.jpg]

Any idea about repairing this calculator is certainly appreciated!

And in the same mail, I received this (inspired by the SR56 vs. HP25 thread http://www.hpmuseum.org/forum/thread-698...light=SR56 ) calculator, which has been missing from my collection so far. Works perfectly, even the original (!) battery can still hold a charge - not something any of my HP-25s is capable of...

[Image: IMG13271_1024px.jpg]

As I own both now (the HP-25 and the SR56) I must say that the SR56 is overall the better calculator. But the Hp25 will always remain the one I would take to the solitary island!

Regards
Max
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11-16-2016, 09:18 PM
Post: #2
RE: Some HP parts inside
Can't tell anything about SR56 but it's known for long that Ariosto's LED calculators featured HP display modules.
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11-16-2016, 09:44 PM
Post: #3
RE: Some HP parts inside
Hello!

(11-16-2016 09:18 PM)HAL_2001 Wrote:  ... but it's known for long that Ariosto's LED calculators featured HP display modules.

Didn't know that! This one must be my first non-working Aristo calculator among 20 or so and therefore I never had to open one of them.
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11-16-2016, 11:30 PM
Post: #4
RE: Some HP parts inside
(11-16-2016 07:54 PM)Maximilian Hohmann Wrote:  Any idea about repairing this calculator is certainly appreciated!

The chip on the right certainly is a driver for the 9 digits. A similar transistor array could replace it. The chip on the left could be replaced by an 28-pin PIC like 16F1518 running a calculator software. Not impossible if you have some time to spend!

Bernhard

That's one small step for a man - one giant leap for mankind.
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11-16-2016, 11:48 PM
Post: #5
RE: Some HP parts inside
The two chips may be the same as the one used in the Aristo M 76, if you have a spare one you can look inside and check for similarities.
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11-17-2016, 08:57 AM
Post: #6
RE: Some HP parts inside
The right chip probably is a transistor array to drive the LEDs, as PANAMATIK already said. The potentiometer might set the brightness (= current flow) of the LEDs.
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