I was recently screwing around with my 84 CSE and while I was taking it apart I broke off the oscillator. Is it possible to order a new one and solder it on (pretty sure it needs to be 15 MHz, right)? I mean, I can always buy a new calculator, however it would be better if i could possibly repair the one I currently have.

Well I did a little bit of research and I'm not sure if you can buy the oscillator by itself. Is there any warranty it?


Edit: I did my best to help

Well... considering the fact that I opened up my calculator and the damage is my fault... I'm guessing no.

However, you can buy oscillators by themselves, I'm just wondering if it will work if properly replaced

Do you mean the thing in the silver cylinder? That's a 32768 Hz crystal used for the clock and dumb USB timing. KermM would know more, but I suspect you could replace it with a crystal from any $10 wrist watch.

If you're talking about the capacitors and resistors used for the CPU clock, you need to replace it with a component of the same rating. Well, you could alternatively install a different resistor to overclock the calculator, but it tops out at about 20 MHz before becoming unstable.

If you're talking about the 40 MHz crystal, it's used for USB stuff. Good luck finding a replacement for it.

I'm guessing a picture pointing out the specific damage would be in order, at this point.

We'll be able to say with more certainty if you can point out which oscillator exactly you mean. (As tifreak beat me to suggesting.)

Have a look at the Datamath board images: http://www.datamath.org/Graphing/JPEG_TI-84PLUS_CSE.htm#PCB
The main suspects are X01B (the 32 kHz crystal, next to the flash chip) and X02D (the 40 MHz oscillator to the left of the ASIC).

Here's a link to the picture as I'm unfamiliar with how to post images here (I'm fairly new): https://www.dropbox.com/s/bwcvi2icge9cb05/2014-07-22%2021.06.56-2.jpg


In case the link doesn't work, it's the cylindrical one next to the two capacitors.

Also, ignore the wires coming from the terminals. That was my temporary fix which worked for a while. With the "fix", the calculator worked perfectly fine, albeit a bit slowly (at 6 MHz, I'm assuming).

Did you snap it flush with its pins?

I'm confused on what you mean. Could you elaborate?

Yes, that's the 32768 Hz crystal. It's also used for generating keyboard scanning interrupts, which is why the calculator won't work without it. I don't see anything that suggests you screwed up the CPU; most likely, any slowness is a result of the keyboard scanning interrupt happening less frequently, making it feel unresponsive. You can find 32768 Hz crystals aplenty in any number of electronic devices. I'm not sure if those are polarized or not, but you should be able to substitute one from a cheap wrist-watch, assuming you can get it soldered on.

tr1p1ea is asking about how close to the board the snapped off pins are. If there's a lot of pin left, it's a lot easier to solder back on. If not, you'll need to a lot more work, and possible scrap off some of the trace to get something to solder to.

How did you manage to break it off from under that glue? Were you trying to lift it up?

Unfortunately yes, I was trying to get to it. Not necessarily my brightest moment. The Pins are pretty much completely removed, there is just some of my solder on the terminals. Would these work as replacements:
http://www.ebay.com/itm/like/281222484122?lpid=82


Also, where would I find these? There's a chance that I may have one of these laying around in some useless junk.

This looks like the right part http://www.ebay.com/itm/10Pcs-32-768KHz-32768HZ-Crystal-Oscillator-2-x-6-mm-NEW-/130896194045?_trksid=p2054897.l5658 although as I've said before, you could also dike one out of a cheap watch. Bonus points if it's a really old watch you find lying around unused. 32768 Hz is a universal standard for timekeeping applications; you can find a 32768 Hz crystal in anything that has a clock, although newer devices may have SMD crystals instead of the tin-can style.

Thank you! I will order these tomorrow and the should hopefully come in soon!

Good luck! We'd be more than happy to give you tips on how to solder the replacement in safely and carefully without shorting anything else on the board with the newly-installed part, and I hope the operation turns out to be an unqualified success. I'm also impressed with how quickly this thread got you to the point where you knew what to order; many thanks to all the people here who were more timely than me in addressing it.

Hooray! The oscillators that I ordered are finally here and I soldered one of them onto the board. The calculator turns on and "works" , however saying that is a stretch. Once I turn it on I end up on the "RAM cleared" message, however, I have to press each button multiple times in order for the calculator to respond.

bump.

You're way into uncharted waters here, but some speculation might be appropriate..

It sounds like timer interrupt frequency is way down, if the keyboard response is poor. This might happen if it were mis-calibrated.
Did you try powering up the calculator without the crystal and if so, what did it do? Do you have any way to measure activity on the lines connected to the crystal to see if it's actually oscillating?

I must applaud you for daring to dig up your graphing calculator like this... maybe it's just stupidity, but I think it's cool that we like to investigate our electronics more closely than others.

At first I did turn it on without the crystal, however I was unable to get passed the "RAM cleared" message. And no, I don't have any way of measuring what's going on in the board.

Also, is there even a chance that I could get this to work? I mean, is it viable, or should I give up?

It's definitely viable. First, are you sure that no other components were damaged? Second, are you sure that you replaced the original crystal with a crystal of the same frequency value? It almost sounds to me like the crystals don't match or some other part of the timing circuit is broken. Please try to run this program and tell us what it says.