[time-nuts] OCXO Adjustment Question

Azelio Boriani azelio.boriani at screen.it
Sun May 19 19:02:58 EDT 2013


Usually this type of failure comes from the startup section of the
power supply. Try to locate the resistor and the electrolytic
capacitor of the driver IC. The resistor (in the 68K - 390K range)
connects the V+ bus to this low voltage capacitor and gives the
startup voltage.

On Sun, May 19, 2013 at 7:19 PM, J. L. Trantham <jltran at att.net> wrote:
> It's nice to have something to do.
>
> Sorry to hear of the 'bad' magic but, at least, it's not the same problem
> all over again.
>
> Joe
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Frederick Bray
> Sent: Sunday, May 19, 2013 12:11 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] OCXO Adjustment Question
>
> Well, I also had some bad magic happen.
>
> Last night, I decided that I would shutdown my HP 8935 so that I could
> move it back to its usual place.  When I turned it on this a.m.  it
> wouldn't power up.  There is a known failure mode in the power supplies
> of the 89XX series.  I will probably just do an exchange for a re-built
> supply.
>
> It looks like I will have a new project for next weekend!
>
> Fred
>
>
> On 5/19/2013 9:10 AM, J. L. Trantham wrote:
>> Good to hear.
>>
>> I love it when magic happens.
>>
>> Joe
>>
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>> Behalf Of Frederick Bray
>> Sent: Saturday, May 18, 2013 5:55 PM
>> To: time-nuts at febo.com
>> Subject: Re: [time-nuts] OCXO Adjustment Question
>>
>>
>> Thanks to all the people who have commented, I believe that I have
>> recovered the original Ovenaire OCXO.  I re-flowed a bunch of solder
>> joints on the PC board(s) and reassembled the oven with the foam. Even
>> without the can over it, it is now stable.  I plan to complete the
>> re-assembly and leave it as it presently is after setting it to a GPSDO
>> with a scope.  I will save the MV89 for another project.
>>
>> Fred
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