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Re: Schaffner explosions (Re: [HP-Agilent-Keysight-equipment] HP8657B Mains Filter Disaster)
开云体育And if you’re talking about HP equipment, we’ve found the engineers at HP did a great job of designing circuits that happily protect the fuse.?Regards, ? Stephen Hanselman Datagate Systems, LLC (775) 882-5117?office (775) 720-6020?mobile a Service Disabled, Veteran Owned Small Business DISCLAIMER: This e-mail and any attachments are intended only for use by the addressee(s) named herein and may contain legally privileged and/or proprietary information. If you are not the intended recipient, any dissemination, distribution or copying of this e-mail and any attachments is strictly prohibited. If you have received this e-mail in error, please immediately notify me and permanently delete the original and all copies and printouts of this e-mail and any attachments.On Apr 3, 2019, at 13:46, Chuck Harris <cfharris@...> wrote:
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Re: HP 8720D - Debugging story
When the VNA boots it goes into Factory preset and shows only option 010. The serial number shown seems correct given the info on the back.That's another sign that someone was messing with the analyzer. Keep that in mind as you proceed, it may give you clues if you run into other oddities. The manual will tell you how to register the hardware options. Once you do that, the menus will look right for your configuration. You should do that before you do any calibration work. The batteries in these instruments last a long time but, once exhausted, they die suddenly. The good news is that the battery only serves for instrument states and the clock. The rest is in the EEPROM. I would take the CPU fan off and look for any clues about the manufacturer and model. Then, find the replacement wherever you can. Keysight will either tell you they no longer sell the fan, or it will cost a fortune if they do. Later versions of this processor board have an inexpensive looking Sunon fan, held in place with a wire spring clip. I can get the Sunon P/N tomorrow, but I am not sure if the thing will attach properly to your vintage heat sink. I do recall having a fan which made noise only when the instrument was upside down (service position). Once I blew out all the dust from it, it got quiet again. Vladan |
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Re: HP 8720D - Debugging story
Derek Kozel
Hi Vladan, When the VNA boots it goes into Factory preset and shows only option 010. The serial number shown seems correct given the info on the back. It seems like I may need to poke around to set the options I have hardware for. I'd like to replace the CPU fan (it's rattling). Is the best shot there to email Keysight with the part number and hope? |
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Re: Schaffner explosions (Re: [HP-Agilent-Keysight-equipment] HP8657B Mains Filter Disaster)
Would a properly sized fuse prevent a fire from happening
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if you fired up a hotplate, and placed it in contact with a curtain? This is a common misconception about fuses and fire protection. They are pretty good at preventing power cords, wall outlets, and house wiring, from burning, but do little for problems like the bad RIFA capacitors. The RIFA capacitors will quite happily light up the printed circuit board, while not blowing a reasonably sized fuse. I have seen them burn clean through a FR4 circuit board... If it had been G10, there would have been more than just smoke. I have seen power transformers that caught fire without blowing the fuse when the rectifier shorted. Fuses save the house wiring, and the power cords, but not much else is certain. -Chuck Harris Dave_G0WBX via Groups.Io wrote: So don’t rush out replacing all your 250 V nominal equipment (which will |
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Re: Schaffner explosions (Re: [HP-Agilent-Keysight-equipment] HP8657B Mains Filter Disaster)
开云体育So don’t rush out replacing all your 250 V nominal equipment (which will be almost all of your equipment), but do rush out to get rid of the crazing 1980s' RIFA capacitors (inside a golden clear plastic blob with lots of cracks) that we are talking about, even when they are inside a Schaffner line filter. Cant help thinking that a power lead with a correctly rated fuse in the plug will reduce the damage, and certainly the fire risk. For the non UK readers, we have HRC fuse cartridges in our power lead plugs, that go into the wall socket.? Saves a lot of embarrassment sometimes, unless you get it very wrong... Might not stop the "Bang"!? But sure reduces the fire risk. Regards. Dave B.
-- Created on and sent from a Unix like PC running and using free and open source software: |
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Re: HP8657B Mains Filter Disaster
开云体育There is a worse smell fortunately rarely encountered any more and that is of a failed Selenium Bridge Rectifier.
Oh good grief
yes!? Once
experienced, never ever forgotten!?? Much like the burnt out
transformer smell too... -- Created on and sent from a Unix like PC running and using free and open source software: |
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Re: Schaffner explosions (Re: [HP-Agilent-Keysight-equipment] HP8657B Mains Filter Disaster)
Hi Should add, that in the USA if on 115VAC mains the main reservoir electrolytic could well be the reason for the smell. With switch mode supplies, which the 8920B will be, on 230VAC it is normally the input filter capacitors that fail and on 115VAC it is the first stage electrolytic storage capacitors that fail. The above is not written in stone. 73 George G6HIG ? ? On Wednesday, April 3, 2019 7:57 PM, RFI-EMI-GUY <rhyolite@...> wrote: Is this same part used in the HP8920B? I ask because my otherwise fine unit outgasses a mild chemical smell when turned on. I am in the US.
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Re: Schaffner explosions (Re: [HP-Agilent-Keysight-equipment] HP8657B Mains Filter Disaster)
Hi I have never worked on a HP8920B power supply, but I have worked on a HP8920A one. The A power supply did have mains input filtering and deteriorating capacitors could well be the reason for the smell. If the B is similar to the A removing the power supply is not a simple task as you first have to remove the power switch plastic actuator assembly to avoid damage when removing the power supply. 73 George G6HIG On Wednesday, April 3, 2019 7:57 PM, RFI-EMI-GUY <rhyolite@...> wrote: Is this same part used in the HP8920B? I ask because my otherwise fine unit outgasses a mild chemical smell when turned on. I am in the US.
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Re: S-parameter test sets: risks of hidden damage
It is pot luck but you can be careful. Look at the vendor and see if they sell other stuff with guarantees as tested. Then if this item says untested you can be suspicious. If the vendor sells everything as not working because they don't know how to test you may get lucky. Physical looks mean little unless they indicate tampering (covers missing, etc) The inputs can be easily blown by putting DC in and burning the tiny 50 ohm terminations on the saphire? substrates. They are not repairable by mere mortals. PeterB On Wed, Apr 3, 2019 at 12:01 PM markhaun2000 <haunma@...> wrote: When looking to purchase something like a 85046a at auction, how concerned should I be about a unit's cosmetic condition, assuming it's being sold as-is?? How easy is it to damage the RF connectors, visibly or invisibly?? The test ports are part of $$$ integrated assemblies, right?? So not easily replaced.? Just wondering how much paranoia is justified, and whether outward signs of abuse or neglect (scuff marks, etc.) are a useful proxy for other, more serious damage.? Is this an item where a return policy or guarantee would be more worthwhile, versus other kinds of test equipment? |
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S-parameter test sets: risks of hidden damage
When looking to purchase something like a 85046a at auction, how concerned should I be about a unit's cosmetic condition, assuming it's being sold as-is?? How easy is it to damage the RF connectors, visibly or invisibly?? The test ports are part of $$$ integrated assemblies, right?? So not easily replaced.? Just wondering how much paranoia is justified, and whether outward signs of abuse or neglect (scuff marks, etc.) are a useful proxy for other, more serious damage.? Is this an item where a return policy or guarantee would be more worthwhile, versus other kinds of test equipment?
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Schaffner explosions (Re: [HP-Agilent-Keysight-equipment] HP8657B Mains Filter Disaster)
On Apr 3, 2019, at 14:34, george edmonds via Groups.Io <G6HIG@...> wrote:
Care to identify where? also it is not unusual in the UK for the mains voltage to be or exceed 250VAC.Sure, 230 V ± 10 % = 207 V..253 V. The UK tends to be at the upper end (historically “240 V”). But when items such as line filters are qualified for a working voltage, tolerances are of course already in the calculation. A 250 V nominal line filter doesn’t explode at 251 V. Or 253 V. These are RMS values anyway… Capacitors don’t care that much about RMS values, and the actual peaks are very much dependent on power quality, so safety margins are copious. So don’t rush out replacing all your 250 V nominal equipment (which will be almost all of your equipment), but do rush out to get rid of the crazing 1980s' RIFA capacitors (inside a golden clear plastic blob with lots of cracks) that we are talking about, even when they are inside a Schaffner line filter. Now, to make this a bit more on-topic, does anyone know a timeline when these capacitors stopped to be specified and built in by HP? I.e., how new does equipment have to be so you can be relaxed about this issue? Grü?e, Carsten |
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Re: E7495A/B software
I modified the file in the e7495 Full 625 Upgrade
I now have a PCMCIA Card that both upgrades the e7495 and patches the time/freq problem I have a zipped file that includes everything you need to make a CF or PCMCIA card that upgrades to 625 and corrects the time problem If anyone wants it I can share the file. Wally KC9INK |
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Re: HP8657B Mains Filter Disaster
Leon Robinson
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-------- Original message --------
From: "george edmonds via Groups.Io" <G6HIG@...> Date: 04/03/2019 6:40 AM (GMT-06:00) To: [email protected] Subject: Re: [HP-Agilent-Keysight-equipment] HP8657B Mains Filter Disaster Hi Nigel As you are in the UK and have access to Toolstation a very useful solvent for many purposes is their PVCu Solvent Cleaner. ?Its great for removing all sorts of unwanted residues and is does not affect many plastics but as usual check first. New UK sourced filtered IEC sockets should have now have ?had the AC ratting of the filter capacitors raised from 250VAC to 275VAC. ?There is a worse smell fortunately rarely encountered any more and that is of a failed Selenium Bridge Rectifier. 73 George G6HIG ? ? On Wednesday, April 3, 2019 11:34 AM, NigelP <nigel-pritchard@...> wrote: Thanks for all the comments. I’ve actually ordered a new one from Digikey UK; bizarrely it’s coming from the USA even though it’s made in Switzerland and ordered from a? UK company!!!!
?
They had the best price but I had to order something else as well to get to the ship-free price L. I ordered a big fan to sit on the bench to suck away solder smoke ….. and the
burned-out filter remnants. You just can’t remove that junk, it seems to be permanently stuck to whatever it oozes out on to; tried all sorts of solvents to no avail and the house still stinks of it! Could try petrol I suppose.
?
I did attempt to try to use the unit post burn-out by peeling off the earth screen but the actual filter is fully potted and you can’t physically or electrically separate it from the rest of the circuitry so no choice but to replace the whole thing before
you can get your generator operating again L.
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Regards
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Nigel G8AYM
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Re: HP8657B Mains Filter Disaster
Hi This last email contradicts itself, also it is not unusual in the UK for the mains voltage to be or exceed 250VAC.? George G6HIG On Wednesday, April 3, 2019 1:04 PM, Carsten Bormann <cabocabo@...> wrote: On Apr 3, 2019, at 13:40, george edmonds via Groups.Io <G6HIG=[email protected]> wrote: > > New UK sourced filtered IEC sockets should have now have? had the AC ratting of the filter capacitors raised from 250VAC to 275VAC. That has nothing to do with the problem here, which is not that the rating was marginal (it wasn’t), but that the capacitors in the filter were failing over a long time of use. The outer plastic molding of the capacitors which was meant to be watertight was developing cracks over time and let moisture in.? Keeping the devices warm and operating could delay the moisture ingress for decades, but taking a device out of service and storing or shipping it in a moist environment without the benefit of operational heating could make them more susceptible — and that is often the state we find these devices in. When a large enough internal discharge happens, the self-healing no longer works and enough plasma develops that the capacitor essentially becomes one big short and dissipates tens of kW for a short time, melting and boiling its plastic as well as the tar-like substance with which the line filters are filled.? High energy + confinement in filter metal enclosure = explosion. Apparently, using the 250 V capacitors in a 100/120 V environment leads to enough safety margin that the problem doesn’t occur a lot there, which may be the reason that some people think this is a rating problem.? I bet if you let the capacitors rot some more, it will occur there as well. Modern capacitors of this kind don’t just get dropped into an outer molding thermoplastic, but are molded into a cup of more resilient plastic. Grü?e, Carsten |
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Re: HP8657B Mains Filter Disaster
On Apr 3, 2019, at 13:40, george edmonds via Groups.Io <G6HIG@...> wrote:
That has nothing to do with the problem here, which is not that the rating was marginal (it wasn’t), but that the capacitors in the filter were failing over a long time of use. The outer plastic molding of the capacitors which was meant to be watertight was developing cracks over time and let moisture in. Keeping the devices warm and operating could delay the moisture ingress for decades, but taking a device out of service and storing or shipping it in a moist environment without the benefit of operational heating could make them more susceptible — and that is often the state we find these devices in. When a large enough internal discharge happens, the self-healing no longer works and enough plasma develops that the capacitor essentially becomes one big short and dissipates tens of kW for a short time, melting and boiling its plastic as well as the tar-like substance with which the line filters are filled. High energy + confinement in filter metal enclosure = explosion. Apparently, using the 250 V capacitors in a 100/120 V environment leads to enough safety margin that the problem doesn’t occur a lot there, which may be the reason that some people think this is a rating problem. I bet if you let the capacitors rot some more, it will occur there as well. Modern capacitors of this kind don’t just get dropped into an outer molding thermoplastic, but are molded into a cup of more resilient plastic. Grü?e, Carsten |
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Re: HP8657B Mains Filter Disaster
Hi Nigel As you are in the UK and have access to Toolstation a very useful solvent for many purposes is their PVCu Solvent Cleaner. ?Its great for removing all sorts of unwanted residues and is does not affect many plastics but as usual check first. New UK sourced filtered IEC sockets should have now have ?had the AC ratting of the filter capacitors raised from 250VAC to 275VAC. ?There is a worse smell fortunately rarely encountered any more and that is of a failed Selenium Bridge Rectifier. 73 George G6HIG ? ? On Wednesday, April 3, 2019 11:34 AM, NigelP <nigel-pritchard@...> wrote: Thanks for all the comments. I’ve actually ordered a new one from Digikey UK; bizarrely it’s coming from the USA even though it’s made in Switzerland and ordered from a? UK company!!!!
?
They had the best price but I had to order something else as well to get to the ship-free price L. I ordered a big fan to sit on the bench to suck away solder smoke ….. and the
burned-out filter remnants. You just can’t remove that junk, it seems to be permanently stuck to whatever it oozes out on to; tried all sorts of solvents to no avail and the house still stinks of it! Could try petrol I suppose.
?
I did attempt to try to use the unit post burn-out by peeling off the earth screen but the actual filter is fully potted and you can’t physically or electrically separate it from the rest of the circuitry so no choice but to replace the whole thing before
you can get your generator operating again L.
?
Regards
?
Nigel G8AYM
?
?
?
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Re: HP8657B Mains Filter Disaster
开云体育Thanks for all the comments. I’ve actually ordered a new one from Digikey UK; bizarrely it’s coming from the USA even though it’s made in Switzerland and ordered from a? UK company!!!!
?
They had the best price but I had to order something else as well to get to the ship-free price L. I ordered a big fan to sit on the bench to suck away solder smoke ….. and the
burned-out filter remnants. You just can’t remove that junk, it seems to be permanently stuck to whatever it oozes out on to; tried all sorts of solvents to no avail and the house still stinks of it! Could try petrol I suppose.
?
I did attempt to try to use the unit post burn-out by peeling off the earth screen but the actual filter is fully potted and you can’t physically or electrically separate it from the rest of the circuitry so no choice but to replace the whole thing before
you can get your generator operating again L.
?
Regards
?
Nigel G8AYM
?
?
?
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