[sdiy] MCU Xtals

[Jay Schwichtenberg]

Do you know who made the processor?

Some processors can take either a crystal or an external oscillator. 
TYPICALLY if the crystal is hooked up directly it is usually hooked to 2 
processor pins. If there is an external oscillator then one pin with the 
other either open or grounded. USUALLY if an external oscillator is used 
inverting logic chips are used for the circuit. Might look to see if the 
crystal is hooked to an inverter chip.

Then there are parallel and series resonating crystals.

https://www.maximintegrated.com/en/design/technical-documents/tutorials/7/726.html

Jay S.

On 8/22/2022 9:22 PM, Michael E Caloroso via Synth-diy wrote:
> I have a dead Lync LN1000 keytar I bought a few years ago, it has been 
> on the back burner during elder care with my aging parents and job 
> relocation.
>
> I'm hardly a novice restoring embedded systems but this thing has me 
> stumped.  There's no schematics.  The last time I was in this thing, I 
> repaired the voltage regulator and the unit sometimes worked, then not 
> at all.  I'm powering it from a bench supply not from batteries.  I 
> traced the problem to the master clock on the mcu, nothing there.  
> Tried replacing the xtal with no luck.
>
> Now I'm beginning to suspect that I might have installed the wrong 
> xtal.  Where's a good technical resource on mcu crystals?
>
> Also the mcu is one of those quad leadless packages and I can't for 
> the life of me figure out how to pry the mcu out of its socket.  Need 
> to probe the pins in the socket to confirm power rails and signals.  
> At the moment I don't have the mcu info in front of me.
>
> MC
>
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