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 Post subject: Simpson 260 - Meter Problem?
PostPosted: Jan Mon 09, 2017 2:17 pm 
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Joined: Sep Sat 05, 2009 9:45 pm
Posts: 986
Location: Sun City, Arizona
My faithful Simpson seems to be getting tired, like me. In a vertical position the meter needle hangs up about half way up the scale. In a horizontal position it works fine. I thought it was static electricity until I found it would work perfectly by changing the position of the instrument. Thank You All!


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 Post subject: Re: Simpson 260 - Meter Problem?
PostPosted: Jan Mon 09, 2017 8:44 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1918
Location: Oswego, NY, USA
If its pivot-bearing is either adjusted too loosely (or too tightly, in some cases) or getting worn out (if it has ever been dropped & jarred against a table or floor, bearings can go out of adjustment or needles get bent), then the back of the needle pointer (or other close, moving parts) may be rubbing (usually on the number scale) when it's in vertical position, stopping the needle at half scale, which is easy for you to check visually before removing any parts. To repair, use a clean workbench free of dirt, metal filings, pet hair, etc. our two kitty-cats prefer to help me repair meter movements by swatting at the moving needles on the repair bench; remove the bakelite bezel (the part with the glass in it) by removing the screws from the backside and carefully bend the pointer to straight (I use a fine-tip stainless non-magnetic tweezer), the correct distance from number scale, or adjust the top bearing height (usually turning the inner bearing screw about 1/4 turn or less does it; some brands have a thin/jamb locking nut that needs to be first loosened before turning the inner bearing screw..) if needed to free up the armature, or remove any bits of iron or dirt that may be hiding in the gap (between the armature winding and magnet poles) keeping needle from moving fullscale. Sometimes dirt in the gap shows a problem only in one orientation. I use thin, cut rolled pieces of masking tape to remove stuff from the gaps; keep tape slivers and tweezers away from the fragile armature winding and springs or taut band which are easily damaged. Good lighting and steady hands help. The newer Taut-band (aka "Suspension") meter movements can get damaged either from mechanical jars (dropping, etc.) or electrical overload (which can burn and remove spring-temper from the taut-spring band). Last week I was testing a Simpson 0-10uaDC taut-band movement, and by mistake placed 20ua thru it for less than 1 second, damaging the thin taut-band which carries the current to the windings.....I was able to re-adjust its zero set point, but now its linearity is way off....lesson learned.


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 Post subject: Re: Simpson 260 - Meter Problem?
PostPosted: Jan Tue 10, 2017 11:25 am 
Member

Joined: Sep Sat 05, 2009 9:45 pm
Posts: 986
Location: Sun City, Arizona
Thank You for your excellent reply. Meters are so delicate. I'll give it a try and see what I can do. I always dread fooling with meters. I'll post my success or failure. Thanks Again!!


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 Post subject: Re: Simpson 260 - Meter Problem?
PostPosted: Jan Wed 11, 2017 8:30 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1918
Location: Oswego, NY, USA
Practice makes perfect, so they say. We've all made mistakes & wiped out a few meters. If you have any other meters (panel meters or movements in other VOM's..) that you don't care so much about and maybe having similar problems....you could try working your skills up on them first?


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 Post subject: Re: Simpson 260 - Meter Problem?
PostPosted: Jan Fri 13, 2017 10:49 am 
Member

Joined: Sep Sat 05, 2009 9:45 pm
Posts: 986
Location: Sun City, Arizona
Meter is working great again. The Needle was slightly bent. I do have a stainless set of tiny tweezers and just barley used them. I now have my old faithful back and it seems perfect. Thank You for your advice and perfect description of the possible problems and how to fix them. I'm trying to remember if I exposed the instrument to any shock recently. Probably did and never noticed it. David


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