[time-nuts] HP Stories: An architectural view of the HP 5060/5061 and awkward oscillator adjustments.

[Adrian Godwin]

Just to sneak that back on-topic .. the most recent tant failure I had was
in a KS-24361. It was after the dc-dc converter so it didn't look like a
short to the input - it just increased the current draw. Running off a
cheap laptop supply, which overheated and melted instead of shutting down
or blowing a fuse. It took out the breaker for the whole ring main.

Replacing the tant was the only action necessary for the KS-24361 itself.
No other internal damage.

On Sun, Feb 24, 2019 at 2:02 PM Adrian Godwin <artgodwin at gmail.com> wrote:

> I think I've had as many shorted-out tants as dried-out electrolytics.
> It's just that they appear in 80s gear instead of 60s. Then there was the
> flood of high-esr electrolytics from when - early 2000s ?
>
>
> On Sun, Feb 24, 2019 at 1:10 PM Rice, Hugh (IPH Writing Systems) <
> hugh.rice at hp.com> wrote:
>
>> Several people have asked about the Len Cutler ban on Aluminum
>> Electrolytic Capacitors in HP Frequency Standards.   Rick Karlquist could
>> shed more light on this too.   The legend of the ban was passed along to
>> me, perhaps by Lou Mueller, who liked to tell stories of the old days.   In
>> 1985, we were not taking the ban literally.   For example, the 2400uF main
>> power supply filter capacitor was AL-Electrolytic, as were a few other
>> smaller capacitors on the power regulator.   I sidestepped the capacitor
>> issues on my simple battery charger by not having a filter cap after the
>> transformer/full-wave-bridge, and just used 120 Hz pulses, since the
>> battery didn't care about DC vs. pulsed DC.   (I thought it was pretty
>> clever to leave out the main filter cap.)     Where possible, Tantalum
>> capacitors were used.    For the few places where AL caps were used, they
>> were heavily de-rated, operating at 50% of rated voltage for example.
>>
>> As one reader pointed out, back in the 1965 when the 5060A was developed,
>> AL-Electrolytic caps were likely a lot less reliable than in 1985 when I
>> worked on the 5061B.
>>
>>
>> From: time-nuts <time-nuts-bounces at lists.febo.com> On Behalf Of Rice,
>> Hugh (IPH Writing Systems)
>> Sent: Saturday, February 23, 2019 8:49 PM
>> To: time-nuts at lists.febo.com
>> Subject: [time-nuts] HP Stories: An architectural view of the HP
>> 5060/5061 and awkward oscillator adjustments.
>>
>> Hello Time-Nuts,
>>
>> .... Stuff deleted .....
>>
>>
>> It was fantastically reliable. Only linear power circuits, with robust
>> heat sinking of all power devices. The legendary Len Cutler ban on aluminum
>> electrolytic capacitors. 5060s were still in use in 1985, after 20 years of
>> constant operation. Likewise, 5061As were abundant in time standards for
>> 25+ years until they were replaced by the 5071A in the 1990s.
>>
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>