Oscillator NOT

[Nigel Goodwin]

If you probe osc1 it will stop the osc even with a 10x probe. So you probe osc2. Got that.

I've scoped hundreds of micros over the years, with a x10 probe it works fine on either the input or the output, I've never found an exception to this. Mostly you don't even know which is which, so stick it on one, if it doesn't work stick it on the other - just in case! - but I've never found one that works on one pin and not the other using a x10 probe.

From a service point of view I usually scope directly on the crystal, simply because it's more obvious than finding the chip pins.

 

[3v0]

I just removed the resonator and replaced it with two 2 inch long wires.
The wires are soldered to the pads the resonator came off of.

I stuck a resonator in a breadboard, grounded the resonator to the breadboard (which was powering the PCB). They share gnd and pwr.

Hooked the osc wires to the breadboard.

It works.

What does this prove.
The PIC is programmed OK.
The pwr and gnd to the PIC are OK
The connections from the osc pads to the PIC are OK

About the ony thing left would be a bad resonator but I had
checked it prior to soldering it in. I also checked the resistance
between the resonator pads and the socket pins.

I used a new resonator on the breadboard because the pins on the old one were too short. So it could be that the resonator was damaged when I installed it but that is not likely.

It should be noted that I lost an outside resonator pin when desolder it for the 2 or 3rd time.

I understand that over 99% of the time the problem is improperly programed chips and wiring errors.
This still looks like a layout problem to me but I would not for sure say that I have verified that.

 

[Blueteeth]

Hey, just eneded my other topic about my osc issues.......mine was a fussy PIC

I'm still thinking yours was a noise problem, perhaps driving the resonator with HS mode? regardless of its value, as I read that resonators require higher power driving.

Blueteeth

 

[luisgerman]

I've scoped hundreds of micros over the years, with a x10 probe it works fine on either the input or the output, I've never found an exception to this.

Not for design or analysis purposes.

For example, an overdrive can be visually demonstrated by looking at the Osc-Out pin (OSC2), which is the driven pin, with an oscilloscope. Connecting the probe to the Osc-In pin will load the pin too much and negatively affect performance.

 

[Nigel Goodwin]

Not for design purposes.

For 'proving it's running' purposes.