Simpson calibration

[Erik K]

A couple versions of the Simpson 260 manuals give instructions on some calibration tasks. I haven't found one that discusses how to set the meter shunt and meter series resistors, so I derived a procedure myself.

Maybe someone reading has the actual Simpson procedure, and if so, please post or E-mail me if it's something not postable.

I've always set the meter series resistor first, then set the overall meter sensitivity with the meter shunt resistor next, but I've started wondering if the shunt should be set first instead. It's possible that the order makes no difference, since the meter series resistor is set in isolation. Does anyone know?

This schematic is a typical 260. In this example, R-27 is the meter series resistor (as it's similarly designated in lots of Simpson models), and R-32 is the shunt.

[Leigh]

Hi Erik,

Ordinarily meters which use a shunt are slightly more sensitive and higher resistance than nominal. In this case the bare movement might be 48 microamps and 2000 ohms. This allows the shunt to be set to bring both parameters to nominal simultaneously. I would adjust that first, then set the calibration.

The FS current is the important parameter. Adjust for exactly 50 uA FS. Then set R-27 for the required total series resistance and basic range calibration, which is 2000 ohms (0.1 volt) FS per the schematic note.

[Alan Douglas]

I can mail you a xerox of Army TB 9-6625-961-35, the depot cal procedure.

The sequence is 50µA, 250mV, DCV & I ranges, 250VAC, 2.5VAC, AC V ranges.

R31 (250VAC) is on the upper right as you face the back of the meter. R28 (2.5VAC) is on the upper left.

[Erik K]

Thanks for the info. It sounds like my own procedure was backwards. I had been setting the series resistor then using a 50uA current source to set the shunt resistance after that. Going back to a hint from an older Simpson 260 schematic, I had been setting the series resistance with the shunt disconnected, but it sounds like that's not right.

Thanks for the offer to mail that calibration document. I'll E-mail you my address.

[KENSTV]

Alan- could you e-mail me the cal procedure also, working on my 260 series 3 (my favorite meter) smoked resistors need to recalibrate

Thanks Ken sewcool9000_at_hotmail.com

[David Kulka]

Alan, if you'd email it to me as well, I'd appreciate it. david_at_studioelectronics.biz

[Alan Douglas]

I can't email them: they're not scanned and I'm on dialup anyway. I ran out of already-xeroxed copies, and since it's 24 pages long and the only available xerox machine is right next to the boss's desk at work, I have to watch what I sneak in. I did make a couple of extra copies of the older procedure TB 9-6625-961-50 which covers up to the series 5 260s. If that will do (I don't know which models you have) send me an email (adouglas at gis.net) with a mailing address.

Given some time I can copy the longer procedure. Actually all the models are calibrated alike; only the location of the pots differs. And in fact all you really need is the order to follow, and the pot locations. Most of the Bulletin has what instruments to use (which you won't have anyhow), allowable tolerances and some hand-holding.

[Leigh]

Hi Alan,

If you send me a copy I'll scan it and put it up on the site so folks can download it as needed.

[alltare]

Leigh-

Did you and Alan ever get together about these cal procedures? I need to recalibrate my Simpson 260-6PM and I could sure use a copy of the document, either a scan/pdf or a hard copy..

Thanks.

[majoco]

I have the Army copy of TB9-6625-2354-35 as a PDF. If you PM me with your email ads I'll send it to you.

[Alan Douglas]

Leigh picked up his marbles and left the Forum some years ago.

[Fred Scoles]

Deleted

[majoco]

I have sent a pdf of the army procedures to Leigh. I guess he'll post it up on the site sometime.

If he doesn't, then PM me your email address and I'll send you the pdf file. Anybody, I don't mind. Better if I get a few to do at the same time.

[alltare]

Marty,
Thanks for the offer. I have PM'd you with my email address.

Thanks to Fred, too, for the info you posted. I have a schematic, but it's always nice to have the factory recommended procedures for calibration, although what you said makes perfect sense.

alltare

[alltare]

I received the Army calibration manual TB9-6625-2354-35 from Martin, and I have uploaded it to the web for others to view. You can download 'Simpson Multimeter Calibration.PDF' from
http://www.mediafire.com/?tddo70f3rcdgr1d

It's an 845 KB acrobat/pdf file. It will tell you everything you need to know about calibrating the Simpson 160, 260-6 series, 260-7 series, 260-8 and -8P, and 270-4. No photos, parts layouts, or schematics however, but you can get many of those at
http://www.simpson260.com

Thanks again, Martin.

Alltare
======================

[dholland]

Heh, I went to save a copy of the PDF (Many thanks for making it available) and found I already had a copy. but I was looking in my archives, I stumbled across this PDF:

"simpson_260-4_calibration.pdf"

Looks like a copy of the factory PDF for calibration, for the 4 series. I dunno if it's of use now that Alltare posted the mil. cal proceedure, but if anyone wants it, I stuck it up on my bit of mediafire space as well.

http://www.mediafire.com/download.php?jxo6md3f8546o18

Cheers.

David

[Alan Douglas]

For what it's worth, some notes from my copy of the earlier mil procedure, showing locations of the various pots. I used to repair these where I work.

Simpson_pot_locations.jpg (25.96 KiB) Viewed 9657 times

[alltare]

Well, this is embarrasing. It turns out that http://www.simpson260.com has not only the cal procedures that Marty supplied, but they also have the procedures for earlier versions of the 260. I looked at that site a dozen times and completely overlooked the 2 army pubs. They also have "Simpson 260 Series 3 to 6 repair manual" (Sears 1976 Edition) which gives pictorial adjustment locations for most models. All 3 pubs appear to agree with Alan's info (Thanks, Alan). The Sears document includes the full schematic of the 260-6P's protection circuit, which I have not seen elsewhere. All of these manuals, and tons more simpson info, are available near the bottom of page 1 of their manuals list.

Direct addresses:

Calibration procedure for the Simpson 260 up to Series 5 and the 270 Series 1-2-3:
http://www.simpson260.com/downloads/tb9 ... 352-35.pdf

Calibration procedure for the Simpson 160, the 260 from Series 6 to 8 and the 270 Series 4-5
http://www.simpson260.com/downloads/tb9 ... 354-35.pdf

Simpson 260 Series 3 to 6 repair manual Sears 1976 Edition
http://www.simpson260.com/downloads/sim ... ctions.pdf

There- that ought to keep everyone happy.

alltare

[alltare]

David -
Thanx for that info. It's different from the army pubs, so worth having. Geez, after years of looking, I suddenly have a wealth of info. Now I can REALLY screw things up.

alltare

Heh, I went to save a copy of the PDF (Many thanks for making it available) and found I already had a copy. but I was looking in my archives, I stumbled across this PDF:
"simpson_260-4_calibration.pdf"
Looks like a copy of the factory PDF for calibration, for the 4 series. I dunno if it's of use now that Alltare posted the mil. cal proceedure, but if anyone wants it, I stuck it up on my bit of mediafire space as well.

http://www.mediafire.com/download.php?jxo6md3f8546o18

Cheers.

David

[Fred Scoles]

Deleted