Mystery. Please help identify this component on a board

[steve2004]

Does anyone recognize this blue thing on the board? It says 4.00 Cmz on it, and the pcb says CR1. Any help is appreciated.

 

[KJ6EAD]

4 MHz ceramic resonator?

https://en.m.wikipedia.org/wiki/Ceramic_resonator

 

[steve2004]

Thanks for the response. At first I thought it says 4.00 Ghz on this gizmo. That is a confusion of its own (pretty high frequency). Upon higher magnification I was more confused by what appears to say 4.00 Cmz. It does look like a resonator. Is there any way to test it?
Thanks.

 

[colin55]

Connect is across the crystal terminals of a PIC microcontroller.

They rarely give trouble.

 

[KJ6EAD]

The "CM" mark is stylized such that it appears to be a trademark. The other mark is a script "x" or Greek chi character.

 

[Boncuk]

Is there any way to test it?
Thanks.

Yes, there are two ways to test it.

First: If the connected circuit works alright the resonator should be working.

Second: connect an oscilloscope to either outer pin with the ground probe to the center pin. The scope should display a square wave of 4MHz. If the IC's name is known use the pin "OSCout" for measurement. The opposite pin should be connected to "OSCin".

Here is a little sketch showing the difference between a crystal and a ceramic resonator with built in burden capacitors (BC1 and BC2). (There also crystals with built in burden caps on the market.)

In both cases OSC2 is oscillator out. Valid frequency measurements are made between OSC2 and ground (GND).

Boncuk

 

[steve2004]

Thank you guys, for sharing your knowledge with me. You are a great bunch of guys. Thank you again.
Steve