[time-nuts] Tbolt failure modes
J. L. Trantham
jltran at att.net
Sat May 12 12:25:06 UTC 2012
Ed,
Looking back on the message, I see your confusion. I guess a better
descriptor is 'TBolt Failure' rather than 'failure to communicate'.
Clearly, under both scenarios, it was communicating, as indicated by the
'green' COM 1, though not in all areas.
I did not notice the DAC or EFC voltage but I can easily go back and take a
look at that. I suspect in the 'open' failure, the EFC runs all the way to
the stop while in the 'short' failure, it is able to stay in the game.
My recollection is that the person who originally noted the failure, posted
a picture of his TBoltMon GUI with the failure. When I had my failure, my
TBoltMon GUI looked identical, whatever that was.
I just spent about an hour going back through the Archives and was unable to
find the original post or my reply. The topic could have been 'TBolt
Failure', 'Com Port Failure', 'Serial Port Failure', or similar. Perhaps
someone more savvy with the searches can find it.
In any event, the thing that brought it to my attention was that my TBoltMon
GUI looked exactly like the original posters TBoltMon GUI and when I told
him of my -12V failure, he chased his down to a bad connection at the -12V
wire to pin connection on his power connector that plugged into the TBolt.
I'll take a look at the EFC/DAC data later today.
Joe
-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Ed Palmer
Sent: Saturday, May 12, 2012 2:01 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Tbolt failure modes
Joe,
Interesting tests.
So, in your previous problem, loss of -12V caused loss of communication
while in your recent tests, you didn't lose communication, regardless of
whether the -12V failure was open or grounded. Okay, now I'm totally
confused!
Regarding the frequency / locking behaviour, did you happen to notice
what your DAC voltage was before and during the failures? If the
voltage was positive, the unit may have been able to compensate for the
grounded -12V line, but when the -12V line was open, it wasn't possible
to pull the EFC line low enough to maintain lock. The drop in frequency
is consistent with a rise in EFC voltage, at least in direction. If
that theory is correct, a Tbolt with a negative EFC voltage wouldn't be
able to maintain lock with either an open or grounded -12V failure. In
both cases, the frequency would drop with the open -12V failure causing
a larger drop.
Ed
On 5/11/2012 9:16 PM, J. L. Trantham wrote:
> 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
_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
More information about the Time-nuts_lists.febo.com
mailing list