Order Tray | Contact Us | Home | SIG Lists

[time-freq] REF input problems Reflock 2

Merv Thomas vk6bmt at iinet.net.au
Wed Feb 29 13:51:33 UTC 2012


Hi Luis,

Thanks for the prompt response and information.

There is definitely no short from pin 89 GCLK2 to any adjacent pin so the 
suspect seems to be the CPLD itself.

I wonder in the event that the firmware that was downloaded into this CPLD 
had a glitch in it that pin 89 might have been configured as an output to 
ground instead of an input?

For this reason I have separately emailed you for other files to help 
possibly trace a software fault.   I have the assistance of a highly 
qualified electronics engineer/programmer who is willing to spend time on 
this at no cost to me(a fellow radio amateur(VK6IC).

Any help you or anybody else can provide will be appreciated.

Regards,

Merv  VK6BMT
----- Original Message ----- 
From: <time-freq-request at tapr.org>
To: <time-freq at tapr.org>
Sent: Wednesday, February 29, 2012 8:00 PM
Subject: time-freq Digest, Vol 37, Issue 1


> Send time-freq mailing list submissions to
> time-freq at tapr.org
>
> To subscribe or unsubscribe via the World Wide Web, visit
> https://www.tapr.org/cgi-bin/mailman/listinfo/time-freq
> or, via email, send a message with subject or body 'help' to
> time-freq-request at tapr.org
>
> You can reach the person managing the list at
> time-freq-owner at tapr.org
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of time-freq digest..."
>
>
> Today's Topics:
>
>   1. Reflock 2 (Merv Thomas)
>   2. Re: Reflock 2 (Luis Cupido)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 29 Feb 2012 17:49:29 +0800
> From: "Merv Thomas" <vk6bmt at iinet.net.au>
> Subject: [time-freq] Reflock 2
> To: <time-freq at tapr.org>
> Message-ID: <CE72EC6C488F43828B1583A447124C25 at merv>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original
>
> Hi - I have a populated board that is not working.  The output of the 
> BFT92
> transistor on the REF input chain - that is the input to CPLD pin 89 GCLK2
> is being pulled down to about 180 mv. If I cut the trace on the board to
> this pin then the output from the BF92 goes up to 2.6v  Seems like an
> internal short in the CPLD chip.
>
> The input to pin 91 GCLK3 has 2.6v on it from the BF92 in the VCXO input
> chain which seems correct.
>
> Does this show that the CPLD is not serviceable please?
>
> I know most of the forum comments on this subject go back some years so I 
> am
> hoping that maybe Luis Cupido or someone can answer my question!!!
>
> Regards,Merv  VK6BMT
>
>
>
>
> ------------------------------
>
> Message: 2
> Date: Wed, 29 Feb 2012 11:08:10 +0000
> From: Luis Cupido <cupido at mail.ua.pt>
> Subject: Re: [time-freq] Reflock 2
> To: TAPR time and frequency projects <time-freq at tapr.org>
> Message-ID: <4F4E071A.3020904 at mail.ua.pt>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Hi Merv,
>
> You must be sure that you don't have any short circuit on the CPLD
> pins somewhere, the 180mV may suggest also a short circuit to a pin
> being used as output.
> (I did not check how I have the unused pins, but they are likely to be
> configured as outputs driving ground, so check a short to a unused pin ).
>
> Once you have discarded this short circuit possibility
> the CPLD itself will be the next part to suspect.
>
> Luis Cupido.
> ct1dmk.
>
>
> On 2/29/2012 9:49 AM, Merv Thomas wrote:
>> Hi - I have a populated board that is not working. The output of the
>> BFT92 transistor on the REF input chain - that is the input to CPLD pin
>> 89 GCLK2 is being pulled down to about 180 mv. If I cut the trace on the
>> board to this pin then the output from the BF92 goes up to 2.6v Seems
>> like an internal short in the CPLD chip.
>>
>> The input to pin 91 GCLK3 has 2.6v on it from the BF92 in the VCXO input
>> chain which seems correct.
>>
>> Does this show that the CPLD is not serviceable please?
>>
>> I know most of the forum comments on this subject go back some years so
>> I am hoping that maybe Luis Cupido or someone can answer my question!!!
>>
>> Regards,Merv VK6BMT
>>
>> _______________________________________________
>> time-freq mailing list
>> time-freq at tapr.org
>> https://www.tapr.org/cgi-bin/mailman/listinfo/time-freq
>>
>
>
>
> ------------------------------
>
> _______________________________________________
> time-freq mailing list
> time-freq at tapr.org
> https://www.tapr.org/cgi-bin/mailman/listinfo/time-freq
>
>
> End of time-freq Digest, Vol 37, Issue 1
> **************************************** 




More information about the time-freq mailing list