Trying to figure out the value of a bad xtal.

[itscoldoutside]

I am trying to repair a JFJ Easy Pro disc repair machine, I've narrowed the issue down to a bad crystal. Sadly it's not marked and the micro controller it's connected to either has fake markings or is a custom chip maybe? It controls the timer, the leds and the relay for the motor. The micro is marked N79A1021 and you can see the crystal next to it in the picture, is there maybe a few 'standard' values I can try? I've tried probing the bad one when it does run (heat gets it going briefly) with the oscope but it just stops running as soon as I probe it.

Thanks.

[ArdWar]

If that's the usual ~2mm diameter then it should be 32.768kHz
It would be ridiculous otherwise. Just why...

[Whales]

Your scope probe might be enough load to stop the crystal if the drive circuit is very weak.

Yes that's probably going to be a 32.768KHz watch crystal.

[itscoldoutside]

Thanks guys I'll try one and report back.

[magic]

I think it's a 3mm diameter can and I have seen some few-megahertz crystals in this package in consumer electronics.

[BILLPOD]

Once it is detached from the PCB, there may be numbers on the back, but
may require some optical magnification

[SeanB]

Do not probe directly, just have the scope probe near, and see the biggest signal riding in the noise. Also try turning the crystal around, it just has to oscillate for a few seconds to have you run through the timebase to see what the frequency is. Though I have seen them with 1MHz, 2MHz, the most common is 32 kHz.

Edit to give a datasheet of what is available in that package.

https://mantech.co.za/Datasheets/Products/DTXXXX.pdf

[itscoldoutside]

Thanks again guys, I took a crystal from an old watch and it's working 100% now.