What Is This Component?

Dave Wade dave.g4ugm at gmail.com
Sun Jul 23 17:12:05 CDT 2017


It's a "watch" quartz crystal...

http://www.explainthatstuff.com/quartzclockwatch.html

probably used to set the master frequency for the UART/Serial interfaces...

Dave 

> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Rob
Jarratt
> via cctalk
> Sent: 23 July 2017 23:05
> To: General Discussion: On-Topic and Off-Topic Posts
> <cctalk at classiccmp.org>
> Subject: What Is This Component?
> 
> I am trying to repair my DECstation 220 after a battery leak, and making
some
> reasonable progress. I have reached a component that is unknown to me, so
> I don't know how it is supposed to behave. It is connected to the inputs
of a
> CMOS NAND gate, where I measure a steady voltage of 1.8V, but the output
> of the gate is oscillating, which suggests to me that the gate can't
decide
> what the input is. So perhaps this mystery component could be to blame.
> The marking on it is "KDS0B" (the zero could be an "oh", I am not sure). I
have
> a spare board with the same component where there is a marking of
> "32768". Some searches suggest it might be an oscillator.
> 
> 
> 
> It is QZ1 in the following picture:
> https://rjarratt.files.wordpress.com/2017/07/wp_20170723_22_38_20_pro.j
> pg
> 
> 
> 
> The U56 component in the picture is what QZ1 is connected to (pins 5 and
6),
> on the reverse side of the board the pins are also connected to a resistor
and
> a capacitor.
> 
> 
> 
> If anyone can tell me what QZ1 is I would be grateful, and if there is a
modern
> equivalent, that would also be good to know.
> 
> 
> 
> Thanks
> 
> 
> 
> Rob




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