Question for old-timers re: Simpson meters
in [Repair]
|
Prev: Fan Motor ID ?
Next: Packard Belle EHR2080
From: Mark Zacharias on 17 Jan 2010 08:08 "Jim Yanik" <jyanik(a)abuse.gov> wrote in message news:Xns9D038A55798Fjyaniklocalnetcom(a)216.168.3.44... > "Mark Zacharias" <mark_zacharias(a)sbclobal.net> wrote in > news:000174b0$0$2281$c3e8da3(a)news.astraweb.com: > >> "Jim Yanik" <jyanik(a)abuse.gov> wrote in message >> news:Xns9D02BDB4E1AA6jyaniklocalnetcom(a)216.168.3.44... > >>> Simpson meter movements are usually 50uA FS,but I recall one that was >>> less than that. A BIG meter. >>> >>> One thing to worry about with analog meters is their input Z. >>> It varys with range. digital DMMs don't,and usually have a higher Z. >>> >>> -- >>> Jim Yanik >>> jyanik >>> at >>> localnet >>> dot com >> >> >> Yes, nominally one adjusts the swamp resistor for 50 uA at full scale, >> but I'm not afraid to fudge that a little to get the overall accuracy >> where I want it. I use these things to measure voltage, rarely >> current, and if I am measuring current, it's only going to be >> measuring battery charge current or the like, not a critical >> application. >> >> Mark Z. >> >> > > The thing is,the FIRST cal check/adjustment you make is the basic 50ua > setting,then you go on to check the other ranges and make other > adjustments. That 50ua cal adjust affects ALL the other ranges and modes. > adjusting it to optimize other ranges may hide an out of tolerance > resistor. > > -- > Jim Yanik > jyanik > at > localnet > dot com That's pretty much what I do. Manufacturers procedure first, then tweak as I feel necessary to make it a little better for what I do. When I vary the 50uA adjustment a bit (maybe 1 or 2 per cent), it's because I feel the overall accuracy of the meter is off a bit. Mark Z.
From: Dave M on 17 Jan 2010 17:05 Mark Zacharias wrote: > "Jim Yanik" <jyanik(a)abuse.gov> wrote in message > news:Xns9D02BDB4E1AA6jyaniklocalnetcom(a)216.168.3.44... >> "Mark Zacharias" <mark_zacharias(a)sbclobal.net> wrote in >> news:00b076d3$0$16796$c3e8da3(a)news.astraweb.com: >> >>> "Jamie" <jamie_ka1lpa_not_valid_after_ka1lpa_(a)charter.net> wrote in >>> message news:1xk4n.6308$%P5.991(a)newsfe21.iad... >>>> Mark Zacharias wrote: >>>> >>>>> "Dave M" <dgminala4444(a)mediacombb.net> wrote in message >>>>> news:LcydnZhaWvohgMzWnZ2dnUVZ_o2dnZ2d(a)giganews.com... >>>>> >>>>>> Jim Yanik wrote: >>>>>> >>>>>>> "Mark Zacharias" <mark_zacharias(a)sbclobal.net> wrote in >>>>>>> news:00c8f14f$0$1584$c3e8da3(a)news.astraweb.com: >>>>>>> >>>>>>>> "Jim Yanik" <jyanik(a)abuse.gov> wrote in message >>>>>>>> news:Xns9D005EBA3EB83jyaniklocalnetcom(a)216.168.3.44... >>>>>>>> >>>>>>>>> "Mark Zacharias" <mark_zacharias(a)sbclobal.net> wrote in >>>>>>>>> news:003beb0d$0$2118$c3e8da3(a)news.astraweb.com: >>>>>>>>> >>>>>>>>>> Hi, >>>>>>>>>> >>>>>>>>>> As some of the guys here know, I presently collect old analog >>>>>>>>>> multimeters. >>>>>>>>>> >>>>>>>>>> I recall a picture I saw several years ago of a "wall" of >>>>>>>>>> Simpson meters - maybe 50 or more, used to demonstrate >>>>>>>>>> reliability. They were all being pulsed with DC of perhaps >>>>>>>>>> 0.5 hz or so for years on end and none had failed. >>>>>>>>> >>>>>>>>> >>>>>>>>> that's not surprising; >>>>>>>>> the meter movements are very simple and sealed from >>>>>>>>> contamination. there's not much to fail,especially if you're >>>>>>>>> not transporting them. >>>>>>>>> >>>>>>>>> the batteries leaking or resistors going out of tolerance are >>>>>>>>> the biggest problems with Simpson meters,aside from being >>>>>>>>> dropped. >>>>>>>>> >>>>>>>>>> >>>>>>>>>> Anybody remember this and where can I get a JPG of this, and >>>>>>>>>> maybe a link to the info? >>>>>>>>>> >>>>>>>>>> I've tried Google images etc no luck. >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> Mark Z. >>>>>>>>>> >>>>>>>>>> -- >>>>>>>>> >>>>>>>>> Jim Yanik >>>>>>>>> jyanik >>>>>>>>> at >>>>>>>>> localnet >>>>>>>>> dot com >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> Not surprising except perhaps considering mechanical issues - >>>>>>>> bearings, solder - to-coil connections, spring and/or taut-band >>>>>>>> failure, etc. As I recall, they were running this way for maybe >>>>>>>> over 20 years. >>>>>>>> >>>>>>>> They may have been naked meter movements and not complete >>>>>>>> VOM's. Like to have that picture, though... >>>>>>>> >>>>>>>> Mark Z. >>>>>>>> >>>>>>>> >>>>>>> >>>>>>> those meters on the wall were likely left in one switch position >>>>>>> and thus not any different than a "naked meter movement" with a >>>>>>> resistor in series to measure voltage instead of current. >>>>>>> >>>>>>> BTW,I still have my Simpson 270-3 VOM. Works great. >>>>>> >>>>>> >>>>>> I, too, still have my 260-3 that I bought from Allied Electronics >>>>>> in 1965, while serving in the Navy. It's not totally original, >>>>>> since I replaced the original meter movement in the late 60s >>>>>> with a taut band movement from a damaged instrument, and later >>>>>> selected the range resistors to improve the accuracy. Since >>>>>> then, it has served flawlessly, and on the last calibration, was >>>>>> still +/- 1% on all DC voltage and current ranges. AC and >>>>>> resistance ranges were a bit less accurate, but still well >>>>>> within specs. In all, it was $65 well spent.. >>>>>> >>>>>> -- >>>>>> David >>>>>> dgminala at mediacombb dot net >>>>>> >>>>>> >>>>>> >>>>> >>>>> Models 260-3 and later have internal adjustments which can obtain >>>>> accuracy to a very high degree. The 10 volt range suffers a bit at >>>>> full scale but I adjust mine for best accuracy in the 5 to 5.6 >>>>> volt range, where small differences can be huge in modern >>>>> equipment. Sometimes you just have to use a good digital meter >>>>> though, and I have several of them as well. Yamaha receivers use >>>>> protection circuits where the difference between 1.2 and 1.4 >>>>> volts, for example, can be critical. >>>>> >>>>> Trouble is we often take the readings of a digital as "gospel". >>>>> Recently a co-workers' cheap digital was discovered to have >>>>> approximately a 50% error when we were reading a Vsus line in a >>>>> plasma. We were trying to find why the reading was 295 volts >>>>> instead of the desired 195. After trying a different power supply >>>>> board, it was discovered the multimeter had come up lame. >>>>> >>>>> Mark Z. >>>> You're suppose to calibrate analog scales at 75% of their >>>> deflection. >> >> >> Sez who? >> >>>> >>>> >>> >>> That's a pretty general statement... but sounds like a good idea in >>> many cases. >>> I have an RCA WV-38A one adjustment of which is for 1 mA full scale. >>> >>> Mark Z. >>> >>> >> >> Simpson meter movements are usually 50uA FS,but I recall one that >> was less than that. A BIG meter. >> >> One thing to worry about with analog meters is their input Z. >> It varys with range. digital DMMs don't,and usually have a higher Z. >> >> -- >> Jim Yanik >> jyanik >> at >> localnet >> dot com > > > Yes, nominally one adjusts the swamp resistor for 50 uA at full > scale, but I'm not afraid to fudge that a little to get the overall > accuracy where I want it. I use these things to measure voltage, > rarely current, and if I am measuring current, it's only going to be > measuring battery charge current or the like, not a critical > application. > Mark Z. There are only three adjustments in the Simpson 260-3. The 50uA (250 mv) adjustment sets the basic accuracy for all functions and ranges. This is the only DC adjustment in a 260-3. The other adjustments are for the 250 VAC and 2.5 VAC voltage ranges. If one or more of the DC voltage or current ranges or the other AC voltage ranges need adjustment, you have to change the range multiplier resistors. The same applies to the resistance ranges. All of the instrument calibrations that I have ever done (and I've done a LOT) requires the adjustments to be made at full scale (for both digital and analog instruments). The linearity checks are made at major points throughout the ranges. AC voltage/current and resistance adjustments might be made at points other than full scale, but that's highly instrument dependent, and is specified in the cal procedure. -- David dgminala at mediacombb dot net
From: Mark Zacharias on 24 Jan 2010 09:15 "Jim Yanik" <jyanik(a)abuse.gov> wrote in message news:Xns9D038A55798Fjyaniklocalnetcom(a)216.168.3.44... > "Mark Zacharias" <mark_zacharias(a)sbclobal.net> wrote in > news:000174b0$0$2281$c3e8da3(a)news.astraweb.com: > >> "Jim Yanik" <jyanik(a)abuse.gov> wrote in message >> news:Xns9D02BDB4E1AA6jyaniklocalnetcom(a)216.168.3.44... > >>> Simpson meter movements are usually 50uA FS,but I recall one that was >>> less than that. A BIG meter. <snip> > Jim Yanik > jyanik > at > localnet > dot com That would be the Simpson 269, 100kOhm per volt. They look bigger all right, never seen one in the flesh. There was also the model 262 which looked the same but was conventional 20 kOhm per volt. On the subject of BIG meters, I have a beautiful Hickok 209A which I need to give the refurb treatment and make an AC probe for... now THAT is big! Mark Z.
From: Jim Yanik on 24 Jan 2010 11:49
"Mark Zacharias" <mark_zacharias(a)sbclobal.net> wrote in news:00d82bb7$0$23796$c3e8da3(a)news.astraweb.com: > "Jim Yanik" <jyanik(a)abuse.gov> wrote in message > news:Xns9D038A55798Fjyaniklocalnetcom(a)216.168.3.44... >> "Mark Zacharias" <mark_zacharias(a)sbclobal.net> wrote in >> news:000174b0$0$2281$c3e8da3(a)news.astraweb.com: >> >>> "Jim Yanik" <jyanik(a)abuse.gov> wrote in message >>> news:Xns9D02BDB4E1AA6jyaniklocalnetcom(a)216.168.3.44... >> >>>> Simpson meter movements are usually 50uA FS,but I recall one that >>>> was less than that. A BIG meter. > ><snip> > >> Jim Yanik >> jyanik >> at >> localnet >> dot com > > That would be the Simpson 269, 100kOhm per volt. They look bigger all > right, never seen one in the flesh. There was also the model 262 which > looked the same but was conventional 20 kOhm per volt. > > On the subject of BIG meters, I have a beautiful Hickok 209A which I > need to give the refurb treatment and make an AC probe for... now THAT > is big! > > > Mark Z. > > Yes,that's the model,269.the meter face is almost the entire front of the meter,and the face is about a 8" diagonal,IIRC. I may still have the meter movement in my junkbox,I was making it into a capacitance meter. ISTR I did finish that project.....or did I? -- Jim Yanik jyanik at localnet dot com |