[time-nuts] Temex LPFRS-01

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Yes...
Thank you, and the others, for the suggestions for cleaning/reviving the 
unit, but I can't recommend to my friend to keep a pile of rust (if 
water damage really is the problem) advertised as an used working item.

Regards,
bbg


On 3/17/2012 4:10 PM, Azelio Boriani wrote:
> LPFRS from fluke.l? OK, then open it up and clean it, the LPFRS from
> fluke.l suffers from high humidity/water immersion and usually are very
> rusty inside. I have received one that was very bad but after cleaning with
> tetrachloroethylene (translated with google) it is working properly, maybe
> it will fail soon but now works. I complained with fluke.l and he refunded
> me without asking to ship back the LPFRS.
> TIP: handle with extreme care an opened LPFRS, there is a flexible PCB that
> holds the DB9 connector that can tear in the corners.
>
> On Sat, Mar 17, 2012 at 10:59 AM, MailLists<lists at medesign.ro>  wrote:
>
>> Hello all,
>>
>> a friend purchased from the bay a<subj.>  in the LPRO configuration. After
>> some problems encountered during the first power ups, he asked for help -
>> I'm passing the questions further...
>> After about 9 minutes of warm-up from room temperature (22°C) the lock
>> signal goes low, but after a short time starts to switch low/high with
>> decreasing low periods, until it remains high with short low pulses, spaced
>> at about 2 seconds. After power-down, and sufficient cooling time, the
>> cycle repeats.
>> First step was to reapply the thermal interface to the integrated Al
>> radiator, which helped a bit, the time during which the unit is locked
>> growing slightly.
>> Next step was forced cooling, which helped more, so the lock loss could be
>> attributed with high probability to elevated operating temperatures. The
>> temperature of the base plate (integrated Al radiator) at which lock gets
>> lost is about 40°C, so for a reasonable operation it should not pass about
>> 36°C, at which the power consumption raises to about 17W. That also means
>> that for a 1°C/W heat sinking - obtainable with a larger passive HS or
>> active cooling - operation above 30°C ambient gets practically impossible
>> (except refrigeration, Peltier, etc.).
>>
>> Any further help or suggestions are welcome.
>>
>> Regards,
>> bbg
>>
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