[time-nuts] Opening an Isotemp OCXO

paul swed paulswedb at gmail.com
Fri Oct 28 12:53:39 EDT 2016

I confirmed the pin out matches a 74s30 also. An S30 is TTL. Great pix to
look at.
So 12 V on a 5 V chip is indeed a smoker. Find out why there was 12 V.
OK crazy talk I see a 1K resistor next to the VCC chip. Would anyone be
crazy enough to use a dropping resistor from 12 V to get 5?? Really bad
engineering and I don't actually believe they would. But if true a open
74s30 would indeed show 12 V on pin 14.
Good luck.

On Fri, Oct 28, 2016 at 12:48 PM, jimlux <jimlux at earthlink.net> wrote:

> On 10/28/16 9:13 AM, Scott Stobbe wrote:
>> The OCXO82-59 datasheet lists 12V supply, 5V clock out, could also be a
>> blown regulator in your ocxo, if it is indeed a 12v model.
>> There you go..the design could use a 74S30 as a driver - it's fast,
> fairly good drive, but runs off 5V.  If the regulator is shorted, and you
> put 12V on it, it will cook.
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