If you know what the zener is and what the unregulated supply voltage is,
you should be able to calculate the resistance and power.
Regards
----- Original Message -----
From: "Dave Wood" <[email protected]>
To: "Discussion of precise time and frequency measurement"
<[email protected]>
Sent: Sunday, April 23, 2017 2:31 PM
Subject: Re: [time-nuts] Austron/ Systrom Donner 8181 Time Code Reader
Bill, actually what happened is the zener diode that the resistor fed
shorted and that's the reason it burned up. I have two units with this
issue and I cannot read the resistor value since it burned up. What I
would love to know is what the original value of the dropping resistor
was? 73 Dave
On Sat, Apr 22, 2017 at 11:39 PM, Bill Hawkins <[email protected]>
wrote:
There is usually a power dissipation reason why a resistor becomes
toast, and the reason is frequently a shorted bypass cap or a shorted
device.
Have you measured the resistance to ground of the end of the resistor
opposite the power supply?
Sometimes inputs get high voltages and short the amplifying device.
Sometimes that is reason the units were for sale.
Hope I'm wrong.
Bill Hawkins
-----Original Message-----
From: time-nuts [mailto:[email protected]] On Behalf Of Dave
Wood
Sent: Saturday, April 22, 2017 8:43 PM
Anyone on the list own the above Time Code Readesr. I have one of each,
they are identical with the same issue. I need to identify the correct
value of a resistor in the power supply that provides 27 volts to the
input amp. They are both toast in my units and I do not have a manual.
Thanks in advance! Dave _______________________________________________
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