[time-nuts] Defective Z3801 and strange PS board
I agree that the extra converter is to provide isolation and input voltage flexibility. Mine runs on 24V, and I assume that the first converter is the only difference from the more common 48V units. Also, each stage of conversion should provide additional power supply rejection performance. It is apparently very complicated for what it does, and makes plenty of heat and switching noise. I have often wondered just how much switching and digital noise is actually present in that box environment and in the output signal (common-mode too). It would mostly be 20 kHz and up, so far out from the carrier, and maybe doesn't matter in the intended applications. Has anyone ever looked at or quantified how much extra stuff is there? This jogs my memory of some theories I have about a design weakness in the Z3801A, and how to greatly improve the close-in short-term (1-100 sec) performance. I'll post it after some time to recall and ponder. ___ 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.
Re: [time-nuts] Defective Z3801 and strange PS board
At 18:54 10/07/2011, Ed wrote: I agree that the extra converter is to provide isolation and input voltage flexibility. Thanks to all that answered my questions; very interesting thread. Possibly only input voltage flexibility and EMC considerations, since the isolation was already given by the second block of DC/DCs. 73 - Marco IK1ODO ___ 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.
Re: [time-nuts] Defective Z3801 and strange PS board
On 7/10/11 12:56 PM, Marco IK1ODO wrote: At 18:54 10/07/2011, Ed wrote: I agree that the extra converter is to provide isolation and input voltage flexibility. Thanks to all that answered my questions; very interesting thread. Possibly only input voltage flexibility and EMC considerations, since the isolation was already given by the second block of DC/DCs. not all DC/DC converters provide DC isolation.. A straight buck converter to take a (relatively) high bus voltage down to utilization voltage is an example. ___ 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] Defective Z3801 and strange PS board
Hello group, after many years (about 12, I think) of faithful continuous operation, my Z3801 failed. I opened it, and found that there was no supply to the main PCB. The power supply board in the Z3801 (and Z3805, 58503A, possibly all the series) is marked 58503-60003. It is a very strange board. It seems to have a first DC-DC converter taking 48V input, powering two other DC-DCs that work on 48V (!), one supplying +5/+15/-15V to the main board, the other supplying 5V 4A to a fourth DC-DC that drives the outer oven with up to 18V. Well, it is the first DC-DC that failed. I bypassed it, powering directly the no. 2 and 3 from 48V, and all works again. The questions are: does a schematic for that board exist? Anyone knows why such a complex power supply architecture was adopted? It is not very energy-efficient, all those DC-DC run hot. 73 - Marco IK1ODO / AI4YF ___ 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.
Re: [time-nuts] Defective Z3801 and strange PS board
Marco like you I had lost one of the dc dc converters. As I recall the 48 5V. I simply replaced it with another I had and the 3801 has been working for years. The board is a complicated board and I have not seen schematics for it. Though it would be quite reasonable to develop them. There is a small linear regulator as I recall also. Why such a complicated arrangement is a good question. Though the first inverter is a very wide range 36v-60 V as I recall. Maybe the others could not handle it. But I do agree by todays standards the thing is a power pig and I am to lazy to change it. As they say if its working leave it alone. I did see a while ago that someone had replaced all of the supplies with a more traditional 110 V ac type multi-output supply. Thats should have improved the efficiency at a loss of the ability to run off of battery. I do not run on battery. So no real loss. But I will bet someone will answer you on this thread with far more detail. Regards Paul WB8TSL On Sat, Jul 9, 2011 at 9:43 AM, Marco IK1ODO ik1...@spin-it.com wrote: Hello group, after many years (about 12, I think) of faithful continuous operation, my Z3801 failed. I opened it, and found that there was no supply to the main PCB. The power supply board in the Z3801 (and Z3805, 58503A, possibly all the series) is marked 58503-60003. It is a very strange board. It seems to have a first DC-DC converter taking 48V input, powering two other DC-DCs that work on 48V (!), one supplying +5/+15/-15V to the main board, the other supplying 5V 4A to a fourth DC-DC that drives the outer oven with up to 18V. Well, it is the first DC-DC that failed. I bypassed it, powering directly the no. 2 and 3 from 48V, and all works again. The questions are: does a schematic for that board exist? Anyone knows why such a complex power supply architecture was adopted? It is not very energy-efficient, all those DC-DC run hot. 73 - Marco IK1ODO / AI4YF __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://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.
Re: [time-nuts] Defective Z3801 and strange PS board
Hello Paul, thanks for info. Another list member gave me two good links: KO4BB has the schematic of PS board (!) in http://www.ko4bb.com/cgi-bin/manuals.pl?dir=05)_GPS_Timing/Z3801/Z3801A_Power_Supply and there are some more info in http://www.realhamradio.com/GPS_Frequency_Standard.htm All this confirms my analysis, and since it works well without the first converter I will leave it alone, as you say :-) - if you look at the first converter schematic, it is really quite complex; and if you power the Z3801 from 48V it has nothing to do. Thanks to all for the good info, and thanks to Didier for hosting all the good things. Vy 73 - Marco IK1ODO / AI4YF ___ 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.
Re: [time-nuts] Defective Z3801 and strange PS board
Actually that is a wide range switcher. But useless given we tend to drive these with a reg 48 V supply. Regards Paul On Sat, Jul 9, 2011 at 10:49 AM, Marco IK1ODO ik1...@spin-it.com wrote: Hello Paul, thanks for info. Another list member gave me two good links: KO4BB has the schematic of PS board (!) in http://www.ko4bb.com/cgi-bin/** manuals.pl?dir=05)_GPS_Timing/**Z3801/Z3801A_Power_Supplyhttp://www.ko4bb.com/cgi-bin/manuals.pl?dir=05)_GPS_Timing/Z3801/Z3801A_Power_Supplyand there are some more info in http://www.realhamradio.com/**GPS_Frequency_Standard.htmhttp://www.realhamradio.com/GPS_Frequency_Standard.htm All this confirms my analysis, and since it works well without the first converter I will leave it alone, as you say :-) - if you look at the first converter schematic, it is really quite complex; and if you power the Z3801 from 48V it has nothing to do. Thanks to all for the good info, and thanks to Didier for hosting all the good things. Vy 73 - Marco IK1ODO / AI4YF __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://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.
Re: [time-nuts] Defective Z3801 and strange PS board
My educated guess is that they expected to sell these to telcos, who traditionally run everything in a central office on -48v and running off of ac was an afterthought. On Jul 9, 2011, at 9:43, Marco IK1ODO ik1...@spin-it.com wrote: Hello group, after many years (about 12, I think) of faithful continuous operation, my Z3801 failed. I opened it, and found that there was no supply to the main PCB. The power supply board in the Z3801 (and Z3805, 58503A, possibly all the series) is marked 58503-60003. It is a very strange board. It seems to have a first DC-DC converter taking 48V input, powering two other DC-DCs that work on 48V (!), one supplying +5/+15/-15V to the main board, the other supplying 5V 4A to a fourth DC-DC that drives the outer oven with up to 18V. Well, it is the first DC-DC that failed. I bypassed it, powering directly the no. 2 and 3 from 48V, and all works again. The questions are: does a schematic for that board exist? Anyone knows why such a complex power supply architecture was adopted? It is not very energy-efficient, all those DC-DC run hot. 73 - Marco IK1ODO / AI4YF ___ 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.
Re: [time-nuts] Defective Z3801 and strange PS board
On 7/9/11 7:49 AM, Marco IK1ODO wrote: Hello Paul, thanks for info. Another list member gave me two good links: KO4BB has the schematic of PS board (!) in http://www.ko4bb.com/cgi-bin/manuals.pl?dir=05)_GPS_Timing/Z3801/Z3801A_Power_Supply and there are some more info in http://www.realhamradio.com/GPS_Frequency_Standard.htm All this confirms my analysis, and since it works well without the first converter I will leave it alone, as you say :-) - if you look at the first converter schematic, it is really quite complex; and if you power the Z3801 from 48V it has nothing to do. In the telecom world, the 48V is -48V, with the positive being ground. Maybe that's why? The other thing is that this gives them a way to make multiple versions with different supply voltages by only changing one converter. As others have pointed out, too, it might let you use a wide input range converter as the first step. There's also a matter of using off the shelf converters. I've built more than one piece of lab gear this kind of strategy.. you have a box full of 28V to whatever you need (+5, +/-15V, etc.) so then you need a AC to 28V Thanks to all for the good info, and thanks to Didier for hosting all the good things. Vy 73 - Marco IK1ODO / AI4YF ___ 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.
Re: [time-nuts] Defective Z3801 and strange PS board
Hi Guess 1: Design it all with the first set of switchers, run it through all the fancy do them one time tests. Get to the last test, fail. Project is now well behind schedule. What's the fast fix? Slap on a wider range / lower emission / better isolation / what ever switcher in front of what you have already. Not pretty, but much faster than doing it right. Guess 2: Inventory items reduction fun and games / use the standard parts list. Much easier to design with parts that somebody else has put into the system than to put in new ones. Might even get a gold star for doing it that way. Companies get on those sort of band wagons from time to time. Bob On Jul 9, 2011, at 11:19 AM, bownes wrote: My educated guess is that they expected to sell these to telcos, who traditionally run everything in a central office on -48v and running off of ac was an afterthought. On Jul 9, 2011, at 9:43, Marco IK1ODO ik1...@spin-it.com wrote: Hello group, after many years (about 12, I think) of faithful continuous operation, my Z3801 failed. I opened it, and found that there was no supply to the main PCB. The power supply board in the Z3801 (and Z3805, 58503A, possibly all the series) is marked 58503-60003. It is a very strange board. It seems to have a first DC-DC converter taking 48V input, powering two other DC-DCs that work on 48V (!), one supplying +5/+15/-15V to the main board, the other supplying 5V 4A to a fourth DC-DC that drives the outer oven with up to 18V. Well, it is the first DC-DC that failed. I bypassed it, powering directly the no. 2 and 3 from 48V, and all works again. The questions are: does a schematic for that board exist? Anyone knows why such a complex power supply architecture was adopted? It is not very energy-efficient, all those DC-DC run hot. 73 - Marco IK1ODO / AI4YF ___ 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. ___ 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.
Re: [time-nuts] Defective Z3801 and strange PS board
I have a Motorola based 5 MHz unit, that's a rack mount, that's the same, using a 45-48 Vdc supply, and was told at the time it was due to the Telco standard voltage. I use it with my Racal products, as their timebase is at 5 MHz. By the way, this unit was pulled from a cell tower. Best, Will *** REPLY SEPARATOR *** On 7/9/2011 at 11:19 AM bownes wrote: My educated guess is that they expected to sell these to telcos, who traditionally run everything in a central office on -48v and running off of ac was an afterthought. On Jul 9, 2011, at 9:43, Marco IK1ODO ik1...@spin-it.com wrote: Hello group, after many years (about 12, I think) of faithful continuous operation, my Z3801 failed. I opened it, and found that there was no supply to the main PCB. The power supply board in the Z3801 (and Z3805, 58503A, possibly all the series) is marked 58503-60003. It is a very strange board. It seems to have a first DC-DC converter taking 48V input, powering two other DC-DCs that work on 48V (!), one supplying +5/+15/-15V to the main board, the other supplying 5V 4A to a fourth DC-DC that drives the outer oven with up to 18V. Well, it is the first DC-DC that failed. I bypassed it, powering directly the no. 2 and 3 from 48V, and all works again. The questions are: does a schematic for that board exist? Anyone knows why such a complex power supply architecture was adopted? It is not very energy-efficient, all those DC-DC run hot. 73 - Marco IK1ODO / AI4YF ___ 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. __ Information from ESET Smart Security, version of virus signature database 5851 (20110206) __ The message was checked by ESET Smart Security. http://www.eset.com ___ 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.
Re: [time-nuts] Defective Z3801 and strange PS board
On 7/9/11 8:31 AM, Bob Camp wrote: Hi Guess 1: Design it all with the first set of switchers, run it through all the fancy do them one time tests. Get to the last test, fail. Project is now well behind schedule. What's the fast fix? Slap on a wider range / lower emission / better isolation / what ever switcher in front of what you have already. Not pretty, but much faster than doing it right. Guess 2: Inventory items reduction fun and games / use the standard parts list. Much easier to design with parts that somebody else has put into the system than to put in new ones. Might even get a gold star for doing it that way. Companies get on those sort of band wagons from time to time. not to mention that power efficiency probably isn't a design criteria for this kind of gear. Nobody is going to make a comparison chart between this and a similar product from a competitor and say... Well... that HP unit consumes a watt more, but has -150dBc/Hz noise and the other box has -145 dBc/Hz. I think we should buy the lower power box. Multiple power converters in series is a very, very common scheme. It lets you do a lot of the regulatory compliance stuff (power factor, conducted emissions, conducted susceptibility) in just one place, too. You do a qual run for your series of first line converters, and then you can do whatever you like for all the downstream converters. ___ 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.
Re: [time-nuts] Defective Z3801 and strange PS board
On 07/09/2011 05:26 PM, Jim Lux wrote: On 7/9/11 7:49 AM, Marco IK1ODO wrote: Hello Paul, thanks for info. Another list member gave me two good links: KO4BB has the schematic of PS board (!) in http://www.ko4bb.com/cgi-bin/manuals.pl?dir=05)_GPS_Timing/Z3801/Z3801A_Power_Supply and there are some more info in http://www.realhamradio.com/GPS_Frequency_Standard.htm All this confirms my analysis, and since it works well without the first converter I will leave it alone, as you say :-) - if you look at the first converter schematic, it is really quite complex; and if you power the Z3801 from 48V it has nothing to do. In the telecom world, the 48V is -48V, with the positive being ground. Maybe that's why? Maybe, our trusty good old -48 VDC. :) But if they have the isolation in them, which they usually have, it should not be that which is the reason. The other thing is that this gives them a way to make multiple versions with different supply voltages by only changing one converter. As others have pointed out, too, it might let you use a wide input range converter as the first step. It is available in multiple voltages, so this is much more likely. There's also a matter of using off the shelf converters. I've built more than one piece of lab gear this kind of strategy.. you have a box full of 28V to whatever you need (+5, +/-15V, etc.) so then you need a AC to 28V What we do is that we either do AC to -48 VDC switcher or a filter/fuse module to the internal 48 VDC. Using 48 VDC as internal high-voltage supply is very handy. At first they wanted to use a common centrallized switcher, but starting to do pin-count analysis for currents etc. they realized that high voltage means less current. It is hardly a unique realization so therefore there is a lot of 48 VDC to whatever switchers around. So, 48 VDC is a handy internal voltage, regardless of what is on the outside. Cheers, Magnus ___ 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.
