Can you see the voltage on the yellow dipped tantalum under the board? I
think that is what it is.
----- Original Message -----
From: "Peter Reilley" <[email protected]>
To: "Discussion of precise time and frequency measurement"
<[email protected]>
Sent: Friday, October 28, 2016 3:28 PM
Subject: Re: [time-nuts] Opening an Isotemp OCXO
That seems the most reasonable thing to do.
Pete
On 10/28/2016 3:20 PM, Tom Miller wrote:
It looks like that is the only device that could be damaged by 12 volts.
Can you find a replacement and try running at 5 volts?
----- Original Message ----- From: "Peter Reilley"
<[email protected]>
To: "Discussion of precise time and frequency measurement"
<[email protected]>
Sent: Friday, October 28, 2016 3:10 PM
Subject: Re: [time-nuts] Opening an Isotemp OCXO
The reason that there was 12 volts on the unit was because I put it
there. I should
have tried 5 volts first but the only datasheet that I could find said
12 volts.
All the eBay units that look the same say 12 volts.
Pete.
On 10/28/2016 12:53 PM, paul swed wrote:
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.
Paul
WB8TSL
On Fri, Oct 28, 2016 at 12:48 PM, jimlux <[email protected]> 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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