Path: news.eternal-september.org!eternal-september.org!feeder3.eternal-september.org!border-3.nntp.ord.giganews.com!nntp.giganews.com!Xl.tags.giganews.com!local-3.nntp.ord.giganews.com!nntp.supernews.com!news.supernews.com.POSTED!not-for-mail
NNTP-Posting-Date: Sat, 05 Apr 2025 02:14:04 +0000
From: john larkin <jlArbor.com>
Newsgroups: sci.electronics.design
Subject: Re: Simpson 260 repair
Date: Fri, 04 Apr 2025 19:14:03 -0700
Message-ID: <9a41vj9l373oss9risq32iappfalo3j5i1@4ax.com>
References: <67effc27$6$2789$882e4bbb@reader.netnews.com> <MPG.425a4380329199298a032@news.eternal-september.org>
User-Agent: ForteAgent/8.00.32.1272
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Lines: 36
X-Trace: sv3-m3WBdPOISeZYDcRGX7Alsykf4vcVXn8dTu5Xl8kVX2vXASyAj657pqlkNaT7n16V/3pSIAjs51Et0nU!t9yadkdOe7trknDpxj3oojfREeu9vJ/B67I2h5X8guipe1v40l+aboTDZPzHFEL/S7fWTwHx+vIh!ab5m5g==
X-Complaints-To: www.supernews.com/docs/abuse.html
X-DMCA-Complaints-To: www.supernews.com/docs/dmca.html
X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers
X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly
X-Postfilter: 1.3.40

On Fri, 4 Apr 2025 20:29:43 -0400, Ralph Mowery
<rmowery42@charter.net> wrote:

>In article <67effc27$6$2789$882e4bbb@reader.netnews.com>, 
>user@example.net says...
>> 
>> Picked up a Simpson 260 6M at the local thrift store, I was initially 
>> disappointed to find it had a sticking meter but some gentle rocking 
>> freed it.
>> 
>> Unfortunately the movement resistance is a little high, about 1880 ohms 
>> vs the 1800 in the service manual. This causes the movement to not fully 
>> deflect when 50 uA (sourced from an HP 6177B, and monitored by a 
>> recently lab-calibrated 3478A) is run through it, it goes to more like 
>> 48.5 out of 50.
>> 
>> Is it correct that recharging the meter movement is the only thing that 
>> can help in this situation? It seems a relative error of 3% is actually 
>> still barely within factory spec so probably best to just let it go and 
>> enjoy a meter that's nice enough for the 10 bucks I paid for it, lol
>> 
>> 
>
>For a meter that is over 50 years old that is probably not too bad.  I 
>have 2 of the meters and the book says the meter is 48 uA
> the best I recall and that parallel pot sets it to 50 uA.  So that 
>meter does not seem too bad.  with digital meters getting much closer it 
>is hard to get it in ones head that those old meters were field 
>instruments and not super accurate.  A 50 uA meter that has been banged 
>around for 50 plus years is luck to be that close.
>

Digital meters aren't always honest either, especially on AC ranges.
Some can't even cover the audio range. Some disappear the low 1% of
readings to hide their internal noise floor.