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I've just repaired a 12C!
03-11-2018, 10:51 PM
Post: #1
I've just repaired a 12C!
Some time ago I've bought a 12C marked as "not working" from the evilBay. There were only a few keys working, and most of the segments didn't show up on the display.
I noticed that applying some pressure on the chip, the keys and segments would come back to life, so I guessed it was some fracture on the board or just a bad contact on some of the pins.

Today I got a half decent SMD rework station, so I wanted to try it on the 12C.

After the treatment the keys started working flawlessly and the segments were up again, but half of the screen looked like burned.
I waited till the board fell back to ambient temperature and the screen slowly returned to its original color. After 10 minutes the 12C was again fully working and the screen didn't suffer any permanent damage!

It's a Singapore made unit, and the keys make a "rattle" sound and aren't as good as those of my other 12C made in USA, but nonetheless it's a very nice working 12C which I picked up for less than 10 euros Smile

Now that I have the means to repair and modify all sorts of boards, I might get into modding and repairing stuff. I've got to check the evilBay once again Big Grin

See you!

Software Failure: Guru Meditation

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Antonio
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03-12-2018, 12:35 AM
Post: #2
RE: I've just repaired a 12C!
Congratulations!

Last year my brother asked me to fix the HP-11C I had given him 30 years ago. Two rows of keys did not work (e^x, GTO, GSB, f and 9, 6, 3, Sigma+). He gave me his 11C and I boasted I could fix it in less than a minute. He wouldn't believe it when I returned "his" calculator one minute late with all keys working, until he noticed that one was not his beaten-up 11C. I told him he could keep it and got his old one instead. I tried to fix it later, but lacking both skill and right tools, I think I've ruined it:

[Image: 25885968757_aa80368a70_b.jpg]

No problem, as I am not a collector (however, I don't intend to part with any of my 25+ calculators :-)

[Image: 40756437591_27ca5c6f3a_b.jpg]
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03-12-2018, 02:15 AM
Post: #3
RE: I've just repaired a 12C!
All of those keys are on the same column, the second one in on both ends. That appears to be connected to the 3rd pin down on the right, the one near the 2 in 1LM2. watch out for solder bridges between pins.

Paul.
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03-12-2018, 02:30 AM (This post was last modified: 03-12-2018 02:31 AM by Gerson W. Barbosa.)
Post: #4
RE: I've just repaired a 12C!
(03-12-2018 02:15 AM)Paul Berger (Canada) Wrote:  All of those keys are on the same column, the second one in on both ends. That appears to be connected to the 3rd pin down on the right, the one near the 2 in 1LM2. watch out for solder bridges between pins.

Thanks for the tip! I’ll get some desoldering braid and try again one of these days.

Gerson.
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03-13-2018, 04:08 AM
Post: #5
RE: I've just repaired a 12C!
(03-11-2018 10:51 PM)TheKaneB Wrote:  Today I got a half decent SMD rework station, so I wanted to try it on the 12C.

Showing my unawareness: Could I ask what a SMD rework station is?

thanks
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03-13-2018, 06:48 AM
Post: #6
RE: I've just repaired a 12C!
(03-13-2018 04:08 AM)Duane Hess Wrote:  Showing my unawareness: Could I ask what a SMD rework station is?

Kinda like a soldering iron but more often than not works with hot air. Designed specifically to enable the soldering/desoldering of SMD components (surface mount device).
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03-13-2018, 10:17 AM
Post: #7
RE: I've just repaired a 12C!
yes!

Specifically this one is an Atten 8586, it has both the soldering iron (50W) and the hot air gun (700W) for reflow soldering of surface mount devices. Both functions are digitally temperature controlled.
It's one of the few good Chinese brands, I'd say it's well suited to a hobbyist lab.

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03-13-2018, 10:28 AM
Post: #8
RE: I've just repaired a 12C!
(03-12-2018 12:35 AM)Gerson W. Barbosa Wrote:  No problem, as I am not a collector (however, I don't intend to part with any of my 25+ calculators :-)

Dimmi solo dove sono i calcolatori e ci sarò!

Tom L
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03-13-2018, 01:49 PM
Post: #9
RE: I've just repaired a 12C!
(03-13-2018 10:28 AM)toml_12953 Wrote:  Dimmi solo dove sono i calcolatori e ci sarò!

Ciao, Tom!

Loro sono qui a Curitiba, Brasile. Forse un po’ lontano, ma saresti sempre benvenuto :-)

una vecchia pagina web (alcune non le ho più)

Gerson.
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03-13-2018, 03:51 PM
Post: #10
RE: I've just repaired a 12C!
(03-13-2018 01:49 PM)Gerson W. Barbosa Wrote:  
(03-13-2018 10:28 AM)toml_12953 Wrote:  Dimmi solo dove sono i calcolatori e ci sarò!

Ciao, Tom!

Loro sono qui a Curitiba, Brasile. Forse un po’ lontano, ma saresti sempre benvenuto :-)

una vecchia pagina web (alcune non le ho più)

Gerson.

Chiediamo l'apertura di un subforum in italiano? :D

Greetings,
    Massimo

-+×÷ ↔ left is right and right is wrong
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03-13-2018, 04:21 PM
Post: #11
RE: I've just repaired a 12C!
(03-13-2018 03:51 PM)Massimo Gnerucci Wrote:  
(03-13-2018 01:49 PM)Gerson W. Barbosa Wrote:  Ciao, Tom!

Loro sono qui a Curitiba, Brasile. Forse un po’ lontano, ma saresti sempre benvenuto :-)

una vecchia pagina web (alcune non le ho più)

Gerson.

Chiediamo l'apertura di un subforum in italiano? Big Grin

Italian? I though I was writing English! Smile

Tom L
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03-13-2018, 04:42 PM (This post was last modified: 03-13-2018 04:50 PM by Gerson W. Barbosa.)
Post: #12
RE: I've just repaired a 12C!
(03-13-2018 03:51 PM)Massimo Gnerucci Wrote:  
(03-13-2018 01:49 PM)Gerson W. Barbosa Wrote:  Ciao, Tom!

Loro sono qui a Curitiba, Brasile. Forse un po’ lontano, ma saresti sempre benvenuto :-)

una vecchia pagina web (alcune non le ho più)

Gerson.

Chiediamo l'apertura di un subforum in italiano? Big Grin

Sul serio? Sarebbe una buona idea!
Scherzo, comunque è stato divertente trovare un riferimento ai quei tipi strani (in cui mi includo anch’io) nei fumetti. Meglio fermare qui, prima che mi buttino fuori, fuori dal forum:-)

Last post in Italian (at least for a good while), I promise.

Gerson.
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03-14-2018, 01:58 AM
Post: #13
RE: I've just repaired a 12C!
I echo, Congratulations and way to go Echo!
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