[time-nuts] Thunderbolt serial port problem UPDATE

[shalimr9 at gmail.com]

Fluke.l is using my design except for a number of units which were shipped with 0 ohm resistors where the 3 diodes were supposed to go. This powers the CPU with 5 V instead of 3 and most don't last long at that voltage. However, the symptom is a blank display.

Also, I understand some units have an actual 5 V regulator and some expect a regulated 5 V.

I have tested a total of 9 units, 2 from fluke.l one from Dan Karg and the other are mine against 3 Thunderbolts (2 group buys and one of the original red boxes) and they all work. As long as the serial data is enough to bias on and off the 2N2222, it should work.

Check the wiring and check that the serial data goes to the CPU. There is not much that can go wrong if the CPU is working.

It is possible that the serial input to the CPU is fried while the rest of the chip works, but I have never seen that happen. Yet I have fried a number of these chips (I design HV supplies in my day job).

Didier KO4BB

Sent from my BlackBerry Wireless thingy while I do other things...

-----Original Message-----
From: Chris Albertson <albertson.chris at gmail.com>
Sender: time-nuts-bounces at febo.com
Date: Wed, 13 Apr 2011 17:19:25 
To: Discussion of precise time and frequency measurement<time-nuts at febo.com>
Reply-To: Discussion of precise time and frequency measurement
	<time-nuts at febo.com>
Subject: Re: [time-nuts] Thunderbolt serial port problem UPDATE

On Wed, Apr 13, 2011 at 5:11 PM, bill <billj at ieee.org> wrote:

> ... I bought from flukel (sp) in China. I opened up the monitor
> and re-soldered
> some questionable solder joints and it still doesn't work. The monitor
>  reports "Waiting for
> GPS" and "No Message"


fluke.l's design is not reliable.  I don't think he is getting the
voltages right in the serial interface.  It works I guess but with
small margin for error

=====
Chris Albertson
Redondo Beach, California

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