Not S05 but S30. A 74S30 is an 8 input NAND and the foot pint on the
board, looking
at the inputs and outputs, seems to confirm it.
There is no 5 volt regulator. The power pin is connected directly to
the power
pin of a 74S30.
Pete.
On 10/28/2016 6:50 PM, J. L. Trantham wrote:
I have emailed Peter separately earlier today.
The top side marking of the chip appears to indicate it is a TI 74LS05D.
The datasheet is here:
http://www.ti.com/lit/ds/symlink/sn74ls05.pdf
If it is indeed a 'HEX Inverter', perhaps another 'channel' can be wired in
place to see if it would work without having to find another chip.
Also, I, too, was wondering if it was 5 V or if there was a 5 V regulator on
the board somewhere.
Hope this helps.
Joe
-----Original Message-----
From: time-nuts [mailto:[email protected]] On Behalf Of Tom Miller
Sent: Friday, October 28, 2016 4:18 PM
To: [email protected]; Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Opening an Isotemp OCXO
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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