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 Post subject: Simpson 260 series 5p help
PostPosted: Nov Sun 17, 2019 11:14 pm 
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Joined: Apr Wed 10, 2019 3:48 am
Posts: 143
Does anyone have any experience with the Simpson 260 5p meter?

Just picked one up at a flee market for $5.00. I figured the battery probably leaked on some components, and sure enough when I opened it a resistor and adjustable pot were assaulted. The pot outer casing tab that ties it to the board/solder trace corroded off. I was able to run a short wire from the casing to the solder trace and got a reading from my dmm. Also, one resistor had white corrosion on both of its leads. I cleaned it off best I could, but unable to tell if it damaged the resistor. Of course, the battery leads were corroded, and I cleaned them up.

Put a fresh D battery in, and the meter is surprisingly responding. Did a voltage check on a battery, and appeared accurate, and getting movement in the needle with ohms. Thats as far a I got.

Would like to know if there is an instruction manual and circuit board diagram available?
Would like to know if I should leave the old components, or do they require replacement?
Is it an accurate meter?

Would like any tips or suggestions about this meter.

It looks really cool and well made. And thank you in advance for your help.


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File comment: Simpson 260 series 5p
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File comment: Simpson 260 series 5p
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 Post subject: Re: Simpson 260 series 5p help
PostPosted: Nov Sun 17, 2019 11:32 pm 
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Location: Littleton, MA
Codepug wrote:
Would like to know if there is an instruction manual and circuit board diagram available?

You can find a manual on the Simpson260.com web site:
http://simpson260.com/downloads/simpson ... manual.pdf

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 Post subject: Re: Simpson 260 series 5p help
PostPosted: Nov Mon 18, 2019 1:11 am 
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Joined: Mar Thu 15, 2018 2:23 pm
Posts: 255
Here's a cheat sheet to help you locate things. Use this with your parts list or schematics.

Attachment:
Simpson 260 5P.jpeg
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 Post subject: Re: Simpson 260 series 5p help
PostPosted: Nov Mon 18, 2019 4:19 am 
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Joined: Apr Wed 10, 2019 3:48 am
Posts: 143
Thank you so much for the great information. This gives me a solid start.

I have rebuilt a few tube radios, and know that the common theme is to replace the electrolytics, paper caps, and out of value resistors. Would this also apply to a meter like this one, or should one minimize replacements? Just thinking that the component values replaced must be near exact to ensure accurate operation. Not sure if that is the case? In other words should I check all component values, and if not a match replace them? This could be tough since many of the values are very unusual. Is there a general theme or practice for restoring these meters?


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 Post subject: Re: Simpson 260 series 5p help
PostPosted: Nov Mon 18, 2019 4:53 am 
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I wouldn't just change anything until you run more tests. Check the different ranges, test the overload circuit, etc. Since the unit is old, you may have oxidation issues that prevent you from zeroing your meter in ohms mode. Make notes on where you have problems and go from there. Simply replacing components isn't necessary.


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 Post subject: Re: Simpson 260 series 5p help
PostPosted: Nov Mon 18, 2019 5:25 am 
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Joined: Oct Thu 04, 2018 2:11 pm
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Location: Suburban Chicago
Ceramic caps should not need replacement. In a meter like this the accuracy is dependent on the resistor values. If the meter is accurate on all scales then there is no need to replace resistors. These are good meters, you may well find that there is nothing wrong with yours. I believe the 260 site has links to calibration manuals, if not they are easily found by searching on them. The one I have is a 6M and I like it. Modern digital meters will generally be more accurate and if they have a bar graph scale for tuning they are just as useful. On the other hand if you grew up using analog meters there is just something about them that will tug at your heartstrings. Modern radios are generally better than the old antiques we are here to work on so obviously we as a group can still appreciate old technology even in the face of better modern technology!


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 Post subject: Re: Simpson 260 series 5p help
PostPosted: Nov Mon 18, 2019 5:40 am 
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Joined: Jan Tue 10, 2012 8:39 am
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I agree. Old technology is what brought me here, my foundation of knowledge. I learned to troubleshoot and measure. My frustrations with inadequate gear have been alleviated with today's splendid equipment but the old stuff works as well as ever.

I have some test gear I use frequently that use tubes. A few are almost indispensable. When I need accuracy, stability, and straighforward performance, the modern stuff leaves the old gear in the dust. For day to day operations I am very fortunate to have the best of both worlds.

I confess that I no longer use my Simpson 260 on a regular basis, if at all. It will measure higher voltage than any of the digital meters and for quick continuity or resistance checks it's great. I must remember the high current the Ohms range puts through the unknown, and guide myself accordingly. For low voltages, 20k Ohms per volt isn't very sensitive. But on the 5 kV range it's hard to beat. My biggest issues are its bulk and strange range gaps.

For most stuff these days I use an old HP bench digital voltmeter.

As a side note, off topic, for years I had no idea how important a spectrum analyzer would become.


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 Post subject: Re: Simpson 260 series 5p help
PostPosted: Nov Mon 18, 2019 2:53 pm 
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Posts: 9547
Location: Ohio 45177
That may be equivalent to my military version with the white reset button and orange pointer. I calibrated mine and it is acceptable accuracy. The hardest part is maybe getting an accurate 50 microamps current source to calibrate the meter movement. You need a hi rez accurate meter that goes that low for comparative purposes. The nice feature is that it uses female banana jacks instead of the opposite that the later models need, which is safer for high voltage but needs unique test leads. And in my experience there is more chance of those old black precision resistors changing value than the later meters that use something like Dale metal film types. You may have problems if your D cell terminals are corroded, as the resistance of the battery terminals must be very low to get the X1 ohms to zero. They tend to oxidize on even perfect terminals and every once in awhile you have to shine them up to be able to get a zero. Although a fresh battery helps in that respect. Brush the corrosion off the resistor leads and then clean with alcohol. I don't think it will be a problem unless the corrosion ate thru the leads. If you clean the switch contacts I would use pure isop alcohol, you can wet them and work the switches as that dissolves oxides off of silver fairly well, but I would not put anything that leaves a residue on the switch contacts. Some spray electrical contact cleaners could work too but if they say no residue on the can.

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 Post subject: Re: Simpson 260 series 5p help
PostPosted: Nov Mon 18, 2019 6:07 pm 
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Joined: Apr Wed 10, 2019 3:48 am
Posts: 143
Meter does not zero, probably because there was no #417 15v overload battery in the side compartment. I originally didnt think this was needed to operate the meter. I recently read that the Meter Zero test when at the Rx10,000 switch setting requires this battery.

Also, one of the battery contacts for the D cell is corroded to the point that just a jagged shard remains that contacts the neg side of the battery. I played with it a bit, and does seem to provide a sufficient contact to the D cell. Guess ill have to first figure out how to fabricate a new battery contact. Was first tempted to take the lead from the side battery compartment, but apparently that is needed for other meter functions.

Also, does anyone know where to get a #417 15v battery for this meter? All i can find are 15v that cost $10 for a single battery on Amazon and not sure this is the right battery.


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 Post subject: Re: Simpson 260 series 5p help
PostPosted: Nov Mon 18, 2019 6:47 pm 
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Joined: Jul Mon 01, 2019 4:42 pm
Posts: 220
Location: St. Louis, MO
15V batteries are still being made. The Exell 411A looks like it might work. If you got a 3D printer, someone designed an adapter to use an Exell 504 in the 417 slot: https://www.thingiverse.com/thing:444063

You could probably replace the D cell with a battery eliminator.


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 Post subject: Re: Simpson 260 series 5p help
PostPosted: Nov Mon 18, 2019 11:12 pm 
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Joined: Mar Thu 15, 2018 2:23 pm
Posts: 255
Codepug wrote:
one of the battery contacts for the D cell is corroded to the point that just a jagged shard remains that contacts the neg side of the battery. I played with it a bit, and does seem to provide a sufficient contact to the D cell. Guess ill have to first figure out how to fabricate a new battery contact.

You may be able to still find the battery contact for your meter. Search for Simpson 03-811310. If not, you can look at the image to fabricate your own contact.


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 Post subject: Re: Simpson 260 series 5p help
PostPosted: Nov Tue 19, 2019 1:41 am 
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Joined: Aug Tue 04, 2009 2:15 pm
Posts: 428
Location: Elmira, NY
If it ain’t broke, don’t fix it!
I bought mine brand new in 1963. I have never adjusted the calibration or changed any component other than the fuse, batteries, phenolic case, and glass meter face. I have replaced the leads several times. I had the calibration checked in 1985; it was dead on. I check it against my fluke process caibrator occasionally; never needs adjustment.
My 260 has seen some hard use over the years. It is the first piece of test equipment I’ve ever owned. I still use it every Day.


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 Post subject: Re: Simpson 260 series 5p help
PostPosted: Nov Tue 19, 2019 2:48 am 
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Joined: Jul Mon 01, 2019 4:42 pm
Posts: 220
Location: St. Louis, MO
Y2KEDDIE, when was the last time you replaced that 15 volt battery? The original Eveready isn't made anymore.


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 Post subject: Re: Simpson 260 series 5p help
PostPosted: Nov Tue 19, 2019 5:58 am 
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Joined: Apr Wed 10, 2019 3:48 am
Posts: 143
So I used my dmm to check 30 resistors in the meter. They were all tested in circuit and i will test out of circuit at some point. The following are those that were out of value:

R5 .4 ohms. Should be 238 ohms
R8 825k. Should be 800,000 ohms
R11 534k. Should be 470,000 ohms
R14 3.95meg Should be 113,400 ohms
R15 17.6meg. Should be 15meg
R17 .8 ohms. Should be .47 ohms (wire round resistor)
R24 12.16k. Should be 8200 ohms
R30 4.5k. Should be 5000 ohms

Not sure what % of deviation from the spec is acceptable ?
Also, any suggestions about the type of resistors to use, the wattage, and what % tolerance.

Thank you


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 Post subject: Re: Simpson 260 series 5p help
PostPosted: Nov Tue 19, 2019 3:26 pm 
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Joined: Oct Thu 04, 2018 2:11 pm
Posts: 190
Location: Suburban Chicago
I wonder how critical the battery voltage is? Two 9V batteries in series maybe? With a Zener or several ordinary diodes in series if need be?

The resistors I can see markings on are 1% and that is what I would expect for any resistor in the metering circuit unless they are in series with a calibration pot like R24 and R26 for example. Resistors like that can vary quite a bit as long as the calibration pot has enough range to make up for them. In the protection circuit R11 and R23 can probably be off by 20% without any issues. Resistor size is a rough indication of wattage. The smallest ones are probably half watt the larger ones are a few watts. Modern resistors tend to be higher rated for any given physical size so if you match the sizes you are almost certainly safe. If you want to be sure you would have to analyze the circuit using the voltage and current ranges to see what the dissipation of each resistor is and then apply a safety factor of 2 or whatever you feel appropriate.


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 Post subject: Re: Simpson 260 series 5p help
PostPosted: Nov Tue 19, 2019 5:18 pm 
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Posts: 143
I will either join 2-9v batteries with diodes, or a 9v with 4- 1.5v, or for fun a 9v and another disassembled 9v taking 4cells for use.

Some of the resistor values will be hard to find like 113,400, so maybe come close 114k if available. May go 2-3 watts
And 1%. Think i could use metal oxide or carbon? And, one is “wire-round” 0.47ohm as stated by the parts list. Wonder if that is the same as wirewound?


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 Post subject: Re: Simpson 260 series 5p help
PostPosted: Nov Tue 19, 2019 6:02 pm 
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Location: Littleton, MA
Codepug wrote:
So I used my dmm to check 30 resistors in the meter. They were all tested in circuit and i will test out of circuit at some point. The following are those that were out of value:

R17 .8 ohms. Should be .47 ohms (wire round resistor)

Does your DMM use a 4-wire resistance measurement? Or allow you to zero the test lead resistance before taking a measurement? Because otherwise, this resistor is probably actually 0.47 ohms within specification.

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 Post subject: Re: Simpson 260 series 5p help
PostPosted: Nov Tue 19, 2019 7:49 pm 
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Joined: Apr Wed 10, 2019 3:48 am
Posts: 143
My dmm does not zero to allow for lead resistance.

Forgot that the leads read a 0.3ohm resistance on my meter, which means not .8 but .5 so off by 6.4% of .47 ohm

Hope thats ok for a meter?
Again, not sure how close i need to be to original specified values??


Thanks


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 Post subject: Re: Simpson 260 series 5p help
PostPosted: Nov Tue 19, 2019 7:58 pm 
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Your meter is inadequate for measurement of such low resistance. Even zeroing the leads doesn't do it, as that's not constant. Anything below a couple of Ohms is suspect.

With a power supply and two meters you can measure it better. Supply, say, 100 mA through the resistor, as measured on a meter. While that's flowing, measure the voltage across the unknown. It will be 100 millivolts for each Ohm. So a 0.47 Ohm resistor should show 47 mV. Better accuracy and resolution will obtain if you run 200 mA through, thus getting 200 mV per Ohm of unknown. Don't go much higher, as that will raise the temperature of the unknown too much.


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 Post subject: Re: Simpson 260 series 5p help
PostPosted: Nov Tue 19, 2019 11:54 pm 
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Joined: Aug Tue 04, 2009 2:15 pm
Posts: 428
Location: Elmira, NY
ZombieElvis wrote:
Y2KEDDIE, when was the last time you replaced that 15 volt battery? The original Eveready isn't made anymore.

Mine uses a 1.5 v battery and (4)AA cells,


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