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

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-bounces@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 _______________________________________________

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.iaxs@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-bounces@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. >

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" <w4ej15@gmail.com> To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com> 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 <bill.iaxs@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-bounces@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/mailman/listinfo/time-nuts > and follow the instructions there.

Here is a calculator to determine the resistor value. <http://www.calculatoredge.com/electronics/zener.htm> You will probably have to provide an external supply, at the zener voltage, to know what the current draw is for the calculator. You might find that the original resistor value was too low or the zener wattage was too low for the circuit draw. You might also find a leaky filter capacitor down stream causing the current to be too high. There may be a leaky filter capacitor up stream causing the zener to draw too much current as the peak voltage may have exceeded the original calculations. 73 Glenn 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.iaxs@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-bounces@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/mailman/listinfo/time-nuts > and follow the instructions there. > -- ----------------------------------------------------------------------- Glenn Little ARRL Technical Specialist QCWA LM 28417 Amateur Callsign: WB4UIV wb4uiv@arrl.net AMSAT LM 2178 QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR "It is not the class of license that the Amateur holds but the class of the Amateur that holds the license" ---------------------------------------------------------------------------

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.iaxs@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-bounces@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/mailman/listinfo/time-nuts > and follow the instructions there. > -- Dave Manuals@ArtekManuals.com www.ArtekManuals.com --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

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 <Manuals@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.iaxs@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-bounces@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 > Manuals@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. >