[time-nuts] Tbolt failure modes

Sat May 12 03:16:55 UTC 2012

Well, this prompted a short experiment to test my observations in the past.
I have a TBolt that requires +5, +12, and -12 VDC as separate inputs along
with the antenna.  A year or more ago, another list member posted a question
about a failure of his TBolt, the specifics I do not remember, other than it
included a 'failure to communicate'.

I paid little attention to his issue at that time other than the fact that I
had had another TBolt die in years past while connected to a switching power
supply (computer type) in my shop which had a habit of having frequent power
failures as a result of how a GCFI outlet had been wired.  I still suspect
one of these power failures triggered a 'spike' on the power supply that did
my TBolt in.

However, a couple of days after his post, I noted my current TBolt had
exactly the same failure the list member had posted, interrupting
communication via the serial connection to TBoltMon.  I then noted that my
-12 V supply had died.  I changed power supplies and my TBolt came back to
life.  

I posted the observation and the other list member found a poor connection
at the connector to his TBolt on the -12 V pin.  He repaired the connection
and his problem was resolved.

Tonight, I turned on a CS unit and compared the 10 MHz from the TBolt to the
5 MHz from the CS (5061A) after the TBolt had been up and operational for a
couple of weeks and the CS up and 'Continuous' for about 30 minutes.

I noted that the two were 'locked', as shown by triggering my scope with the
TBolt 10 MHz and with the CS 5 MHz connected to the vertical.

I then disconnected the -12 V supply and immediately connected it to ground.
This left TBoltMon showing 'red' for 'Power Supply' and everything else 'as
it was'.  Even the SV indications were 'green' and AMU indications were
normal.  In addition, the outputs of the TBolt and the CS were still
'locked'.

I then disconnected the -12 V supply from ground and let it 'float' in air,
simulating the failure I had before.  This immediately resulted in 'yellow'
for 'Satellite Tracking', all the SV indications went 'white', and the TBolt
frequency dropped about 24.6 Hz thus proving loss of 'lock'.  

'COM 1' on TBoltMon remained 'green' for both situations.

I then reconnected the -12 V lead to 'ground' and all observations reverted
to the prior observations with the -12 V input grounded with the
frequencies, again, 'locked'.

So, I conclude that the observations are based on exactly what the failure
of the -12 V is, open or short.  Both my prior power supply failure and the
other list member who had posted the question were 'open' failures.

Hope this helps.

Joe

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Ed Palmer
Sent: Friday, May 11, 2012 12:39 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Tbolt failure modes

Are there multiple hardware versions of the Tbolt (other than the 
Tbolt-E)?  My Tbolt has an Intersil 232IBE dual TTL to RS232 converter - 
similar to MAX232.  It generates it's own -12V.  This is the version 
shown on Brooke Clarke's Thunderbolt page:  
http://www.prc68.com/I/ThunderBolt.shtml

Ed

On 5/11/2012 10:56 AM, shalimr9 at gmail.com wrote:
> The -12V is only used to support the RS-232 driver. The CPU should be
running and you should have discipline even without the -12V
>
> Didier KO4BB
>
> Sent from my BlackBerry Wireless thingy while I do other things...
>
> -----Original Message-----
> From: "J. L. Trantham"<jltran at att.net>
> Sender: time-nuts-bounces at febo.com
> Date: Tue, 8 May 2012 21:29:06
> 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] Tbolt failure modes
>
> I had a failure of my -12 V supply that interrupted communications that
was
> resolved by fixing the -12 V supply.  You might want to make sure you are
> getting the -12 V supply in the unit.  I suspect your 24 V supply provides
> power to an internal supply that generates +12, +5 and -12 V.
>
> Might want to check if that is the case for your unit and if the -12 V is
> present.
>
> Hope this helps.
>
> Joe
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of bg at lysator.liu.se
> Sent: Tuesday, May 08, 2012 4:52 PM
> To: time-nuts at febo.com
> Subject: [time-nuts] Tbolt failure modes
>
> Hi group!
>
> Just got a few Thunderbolts. It is a few PN 39448-61 and one PN 38223-61.
> Date codes from 9932 to 0025. This is the "normal" version with a 24VDC
> power board and Tbolt board integrated in a small AL box with red
> markings. One of the receivers is having a problem. Measuring from the
> outside there is:
>
>    1) Takes the same amount of power as the working units.(to the
> resolution measured)
>    2) Has 10MHz output.
>    3) Has 4.9VDC on antenna center pin.
>    4) -8.9VDC stable on rs232 Tx pin (pin2 in DB9)
>    5) 10MHz is 0.7Hz off after many power on hours with known good antenna
>    6) TP9&  TP10 (close to the GPS board power connector) has 4.9VDC
>    7) Tboltmon will not talk to the board.
>    8) There is no serial output at all from the Tbolt.
>
> Differences compared to a good Tbolt
>
>    1) Tboltmon will ofcause communicate.
>    2) After locking 10MHz will be very close to nominal
>    3) TP9 and TP10 shows a square wave (ca 7V pp, 9.795625000kHz)
>
> I have looked at Tom's page at
>
>      http://www.leapsecond.com/tbolt-faq.htm
>
> Brooke's at
>
>      http://www.prc68.com/I/ThunderBolt.shtml#IC
>
> and John's at
>
>      http://www.ke5fx.com/tbolt.htm
>
> Are there other good Thunderbolt sites?
>
> Has anyone done debugging of faulty Tbolts? Comments on what might be
> wrong with my faulty unit? (I am not that experienced in hardware
> debugging...)
>
> --
>
>      Björn

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