Verzonden vanaf Samsung-tablet. -------- Oorspronkelijk bericht -------- Van: volt-nuts-request@febo.com Datum: 22-07-2017 18:00 (GMT+01:00) Aan: volt-nuts@febo.com Onderwerp: volt-nuts Digest, Vol 95, Issue 18 Send volt-nuts mailing list submissions to volt-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts or, via email, send a message with subject or body 'help' to volt-nuts-request@febo.com You can reach the person managing the list at volt-nuts-owner@febo.com When replying, please edit your Subject line so it is more specific than "Re: Contents of volt-nuts digest..." Today's Topics:    1. Re: Datron 4700 manual and options (Fred) ---------------------------------------------------------------------- Message: 1 Date: Sat, 22 Jul 2017 09:27:16 +0200 From: Fred <pa4tim@gmail.com> To: volt-nuts@febo.com Subject: Re: [volt-nuts] Datron 4700 manual and options Message-ID: <61b14813-7e68-278e-7d40-7ae4c88b1318@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed The 4700 is fixed. The 400V issue was caused by missing -15V, That was caused by a shorted tantalum on the Ohms board. It was less then 0,1 ohm but not even discolored. I was curious about the way they die. So a desoldered about 20 tantalums and measured C, D and leakage current. New ones have a very low D, at 1 kHz well under 0,1. Capacitance did not decrease much like electrolytics do, but D does increase over age. Leakage current is as good as zero, (my best leakage tester has only 1 uA resolution so it can not measure leakage in the nA's) The worst D i found was 0.67. They did not leak, so I think they go from good to short in one step. capacitance does not seem to decrease. In electrolytics this is caused by a decreasing oxidelayer caused by the decreasing electrolyte. I replaced a few by electrolytics as a test. The D factor of the 10uF  low ESR panasonic FM caps was better as that of the new 10uF tantalums I had. Most tantalums measured OK, a few had very high D, non of them leaked DC. So I think (based on this to small number test) they get a high D, start to dissipate and as a result of that develop a short. Fred On 07/21/2017 01:59 AM, Todd Micallef wrote: > Fred, > > I used the same values and typically went up to the next higher voltage. I > think most ended up as 35v since I bought them in quantity. Some people > recommend the OS-CON family as replacements. Many of the failed tantalums > fit in a tight space so I just stayed with the original type. > Once the in-guard was repaired, I found a few other boards where the > tantalums on the same rail also failed so don't be surprised if more start > to fail. > > The 4708 service manual is here > https://xdevs.com/doc/Datron/4708/DATRON-4708-CH-SH_c20030307.pdf > It is now uploaded to KO4BB. The 4808 service manual will be very close > since the 4708 and 4808 share similar designs. > > The 4708 uses a LTZ1000 as the reference instead of the array of zeners > used in the 4000 and the lower spec'd 4700. You will have yourself a good > calibrator once it is brought back into service. Be careful around the > displays as there is hardly any room between the glass and front panel. > > Respectfully, > > Todd > > On Thu, Jul 20, 2017 at 12:55 PM, Fred <pa4tim@gmail.com> wrote: > >> Hi Tod, >> >> I just pulled that board (i think) and found a burned 22uF tantalum. >> Tantalum caps should have a very long life unless used on the wrong place. >> I guess this is an example. I do not even stock them, the last bad one I >> had to replace was in a G&M secutest 2 years ago. ( I repair around 10-20 >> Secutests a year and that was the only bad tantalum) >> >> With what type/value cap did you replace them ? >> I found the 4708 manual at KO4BB but that is a user manual without >> schematics. >> >> The calibrator should be OK but before I try to start her I always like >> check things like caps, connectors, solderjoints etc. It really looks like >> new, not even a scratch or dust. It came with a new looking HP8640 and a >> new looking HP counter 5248. Both from the same cal lab (part of a company >> that stayed there) that cal-lab closed about 30 years ago, but all gear >> stayed where it was (I already had received most of their gear a few years >> ago). This were the last things because my friend retires. >> >> Fred >> >> . >> >> On 07/20/2017 04:51 PM, Todd Micallef wrote: >> >>> Fred, >>> >>> Shorted tantalums most likely. I had several on mine that went bad as >>> quickly as I replaced them. I would start with the inguard supply board. >>> >>> I think the 4708 manual is available for download at KO4BB or xDevs. If >>> not, I can dig up something. I have a set of the manuals. >>> >>> Todd >>> >>> On Thu, Jul 20, 2017 at 10:01 Fred <pa4tim@gmail.com> wrote: >>> >>> Today a friend gave me a Datron 4700. It looks like new. It is stored >>>> (working)  for many years in the cal lab he works. He was allowed to >>>> take it home (for me, in return I will repair his SA), He plugged it in, >>>> Fail 1 on the display followed by a sound and a smell. >>>> I opened it but nothing looks burned. >>>> >>>> I can not find a service manual, does someone has one ? >>>> >>>> On the back the label shows no options but if he remembers it well it >>>> should have all or at least most  options. All slots are filled with >>>> pcb's. The "box" in the left upper corner is full and there is a very >>>> small pcb next to it. There is not much room left. Just enough to store >>>> a small multimeter between the huge transformer and that box. >>>> >>>> Fred >>>> www.pa4tim.nl >>>> >>>> _______________________________________________ >>>> volt-nuts mailing list -- volt-nuts@febo.com >>>> To unsubscribe, go to >>>> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >>>> and follow the instructions there. >>>> >>>> _______________________________________________ >>> volt-nuts mailing list -- volt-nuts@febo.com >>> To unsubscribe, go to https://www.febo.com/cgi-bin/m >>> ailman/listinfo/volt-nuts >>> and follow the instructions there. >>> >> _______________________________________________ >> volt-nuts mailing list -- volt-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/m >> ailman/listinfo/volt-nuts >> and follow the instructions there. >> > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. ------------------------------ Subject: Digest Footer _______________________________________________ volt-nuts mailing list volt-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts ------------------------------ End of volt-nuts Digest, Vol 95, Issue 18 *****************************************