[time-nuts] Re: QM10 Quartz chronometer

[Tom Van Baak]

Yes, I placed Don's QM10 photos and IC pin analysis here:

http://leapsecond.com/u/couch/

FYI: the link below is badly mangled due to his email client or ISP or 
Outlook. It is not a time-nuts server problem. Please do not click on 
links like that.

/tvb


On 12/3/2021 3:45 PM, Don Couch wrote:
> Here is signal data and some pictures from one of my QM-10 chronometers. Curiously, the oscillator only produces 8 Hz. Obviously, it must have a high frequency crystal inside the can somewhere.
>
> I set this clock to the correct time on May 23, 2020. It is now five seconds fast!
>
> Tom van Baak kindly noted the pictures are too large for email, so he moved them to http://leapsecond.com/u/couch/<https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fleapsecond.com%2Fu%2Fcouch%2F&data=04%7C01%7C%7Cee0742a79f1e4d8842fe08d9b6abba73%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637741670943146640%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=nNiqsRRttsNVzs88XyMCfeOsqCkRObPymRRRXSw%2BJ0g%3D&reserved=0>
> The picture of the top of the board shows the original backup battery, which I disconnected. I added the round blue-edged supercapacitor (0.047 F with the red and black wires) so the main battery can be replaced without stopping the clock.
>
> Let me know if there are more questions.
>
> Don Couch
>
> Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows
>
> From: Don Couch<mailto:couchclocks at hotmail.com>
> Sent: Friday, November 26, 2021 9:00 AM
> To: Discussion of precise time and frequency measurement<mailto:time-nuts at lists.febo.com>
> Subject: [time-nuts] Re: QM10 Quartz chronometer
>
> I have two of these. They are very nice precision chronometers. If I remember correctly, the frequency is 4194304. The oscillator is a TCXO usually in a small round 8-legged can.  I have never seen a bad one. The most common problem is the backup battery. If it is still there, it is very old and often shorted. There is a diode in series so if the battery is shorted, it does no harm, but I have seen the diode shorted as well. I do not have schematics, but you can trace the battery circuit.
>
> Don Couch
>