Had a model railway shuttle controller expire.
SO went back to schematic and looked to see what might cause the problem.
It looked ok so got the motor driver pdf out.
I had missed putting cap across motor driver power supply and it was putting spikes on the power supply with motor attached.
This had blown up the motor driver.
So replaced the motor driver, add a cap and all ok now.
SO went back to schematic and looked to see what might cause the problem.
It looked ok so got the motor driver pdf out.
I had missed putting cap across motor driver power supply and it was putting spikes on the power supply with motor attached.
This had blown up the motor driver.
So replaced the motor driver, add a cap and all ok now.
Took my 48 year old HP-45 out of the closet for a little work and a trip down memory lane. The original AC adapter died so I wired the cable to a USB plug so I can use a USB power supply. Don't use batteries anymore. Cleaned all the keyboard switches, etc, and now everything is happy as Pi.
One of those - same buttons, different brand - helped me out in HS physics and math exams. My take at the time was more thought could be applied to the problem, offset by the relative ease in doing the calculations versus by hand.
The same calculator was seen with many different faceplates and brand names starting in about 1971. The Olson Electronics store I worked in sold the same thing with the Craig brand. When it first appeared, it was about $200. By the time I left Olson's it was under $100. All were made by TI, or at least the PCB was.
I picked up a TI-83 plus (1999) at a Goodwill store for $2 several years ago. I still have no idea what to do with it. (mathophobia)
I picked up a TI-83 plus (1999) at a Goodwill store for $2 several years ago. I still have no idea what to do with it. (mathophobia)
I own a Sharp PC-1212 I am very found of, but did not use it for months.
Now, I see the LCD display is blurred along an edge as if there had been a leak.
It is still usable but not easy.
I am pissed, I do not understand what happened, could be have been hurt. There seems to be no way I can repair it.
Too bad, it is an extremely clever calculator with plenty of possibilities, yet easy to use.
There might be plenty of new calculators but I will always regret my Casio PC-1212
Now, I see the LCD display is blurred along an edge as if there had been a leak.
It is still usable but not easy.
I am pissed, I do not understand what happened, could be have been hurt. There seems to be no way I can repair it.
Too bad, it is an extremely clever calculator with plenty of possibilities, yet easy to use.
There might be plenty of new calculators but I will always regret my Casio PC-1212
Same thing happened to my Sharp 5100 scientific calculator after 25 years, so into the bin since I have another one.
Many LCD displays do that after a while, like in Fluke DVM displays.
Absolutely.
I bought a Casio PC-1212 in France, later I saw Sharp had the very same one.
Ah, but my trust old Fluke 77 I've had since the late 90's still works like new and no display issues even after dropping it several times.
I was 😨 of that.
Strange that everything had been find for decades and the trouble appeared quite recently.
Very frustrating. It is a bit peculiar, with a crude BASIC programming, the good thing about it, in my opinion.
I have a PSION 3, that has an elaborate BASIC, as boring and brain wrapping as modern high level languages. I do not want this on a pocket calculator.
I will never find another calculator with this clever handy PC-1212 feature.😥
It is a one shot design, it is easier to clone a all blown classic programming stuff.
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I used mine as an algebraic formula calculator. You enter the formula, define constants,
and it does the rest. Then you can change the constants to get revised results easily.
This was done for RIAA phono preamps, before I got an IBM-AT and SPICE.
Notice this photo also shows the LCD rot problem.
http://www.arithmomuseum.com/album.php?cat=c&id=195&lang=en
and it does the rest. Then you can change the constants to get revised results easily.
This was done for RIAA phono preamps, before I got an IBM-AT and SPICE.
Notice this photo also shows the LCD rot problem.
http://www.arithmomuseum.com/album.php?cat=c&id=195&lang=en
Apparently this happens a lot, and on the similar 1211 also. This guy had a fix. It is not clear if he is doing business now.
https://www.tindie.com/products/halfbakedmaker/lcd-replacement-for-trs-80-pc-1-sharp-pc-1211/
1211's with LCD-leaks are very available on eBay. I had a similar machine with Tandy printed on, you'd have to be a geek to know these models apart (I'm sure you will know). Get a sick 1211 and The Half-Baked Maker's fix-kit.
I dig the LED calc with the USB power. That's how I used to run my TI door-stop calc... batteries didn't last forever and were expensive. Just keep my chair near a wall-outlet.
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You can do a lot more with the calculators built into Android phones.
The Linux calculators are also loaded with functions.
I use Windows 7, the calculator is used for plain arithmetic.
Spreadsheets have many functions of course, but on a phone or tablet, too small for my taste.
I have observed that if the calculator or other LCD is under a book or cell phone or other heavy objects, the display gets damaged.
Keep them on top of the pile, or separately in an organizer of some sort.
The Linux calculators are also loaded with functions.
I use Windows 7, the calculator is used for plain arithmetic.
Spreadsheets have many functions of course, but on a phone or tablet, too small for my taste.
I have observed that if the calculator or other LCD is under a book or cell phone or other heavy objects, the display gets damaged.
Keep them on top of the pile, or separately in an organizer of some sort.
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It was in it's case though, but could have shifted out and the case was cracked so not so strong.
Cracked in a backpack fight at school when let to my son, while he was a teen ager, long ago . 🙁
today i repaired 4 NAD amps
1-3130-blown left output-new output transistors plus the driver
2-3020-blown right output-oddly the driver was fine
3-3020-wayward voltages and no power on LED-replaced grounding cap and zener diode
4-3150-blown high side fuses-replaced output transistors and driver
a good day
1-3130-blown left output-new output transistors plus the driver
2-3020-blown right output-oddly the driver was fine
3-3020-wayward voltages and no power on LED-replaced grounding cap and zener diode
4-3150-blown high side fuses-replaced output transistors and driver
a good day
Been having trouble getting PIC16F753 microcontrollers.
So bought in some pin for pin compatible PIC16F1823's.
Software a little different but got it working.
However a pot threshold going into new PIC seemed to work much lower down.
But it worked so cant argue with that and so I sold a few.
Today built up a couple more but decided I needed to know why pot worked much lower down.
For some reason I had messed up the code changes. The A2D wasn't set up right and I had A2D pin set as digital.
Works great now. Just amazed it worked despite software being wrong. It was using digital pin threshold instead of A2D threshold value.
Another mistake made and another lesson learned.
So bought in some pin for pin compatible PIC16F1823's.
Software a little different but got it working.
However a pot threshold going into new PIC seemed to work much lower down.
But it worked so cant argue with that and so I sold a few.
Today built up a couple more but decided I needed to know why pot worked much lower down.
For some reason I had messed up the code changes. The A2D wasn't set up right and I had A2D pin set as digital.
Works great now. Just amazed it worked despite software being wrong. It was using digital pin threshold instead of A2D threshold value.
Another mistake made and another lesson learned.