Glenn, your calculator comes up with the value I first calculated, around 13k. However, I'm pretty sure the original value may have been 4 times higher based on the partially visible bands on one of the resistors that indicates it might have been a 56k. If I use the zener test current in the data sheet and the max current of the load, I end up with about the same value the calculator estimates. But if I use a lower value of zener current and a lower drain from load I end up with a value pretty close to what may have been in there originally. I was hoping someone on the list had an 8181 and could look to see or have a diagram. If I use the lower values then the dissipation of the resistor is within limits but at the high end. Using 13k ups the power to a one watt device, which I realize should have been the value in the first place. Worse case I start with 56k and work down until the circuit is happy again. 73 and thanks!
On Sun, Apr 23, 2017 at 5:50 PM, Artek Manuals <manu...@artekmanuals.com> wrote: > Dave > > If you know the Zener voltage and the supply voltage then calculating a > reasonable value for the series resistor is pretty straight forward > > Dave > > > On 4/23/2017 2:31 PM, Dave Wood wrote: > >> 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 <bill.i...@pobox.com> >> 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:time-nuts-boun...@febo.com] 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 _______________________________________________ >>> >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to https://www.febo.com/cgi-bin/ >>> mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >>> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/m >> ailman/listinfo/time-nuts >> and follow the instructions there. >> >> > -- > Dave > manu...@artekmanuals.com > www.ArtekManuals.com > > > --- > This email has been checked for viruses by Avast antivirus software. > https://www.avast.com/antivirus > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/m > ailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.