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Products => Test Equipment => Topic started by: sarbog on April 15, 2021, 11:36:44 pm

Title: Old DMM Failed Today
Post by: sarbog on April 15, 2021, 11:36:44 pm
FYI,

I have  been  using an  old early 1990's  vintage  Beckman  2020  DMM.  It  failed  today on RMS  voltage..   I  spent an hour,  embarrassingly,   trying  to  figure  out   why my circuit  was not  working  properly. Then  it  dawned  on me   that  maybe  this old DMM  is not  working.   I  did some  comparison  tests  and sure enough  it was my old DMM...   Duh..........

Title: Re: Old DMM Failed Today
Post by: Nusa on April 16, 2021, 01:50:32 am
Before you write off your old meter, make sure you try it with a new battery.
Title: Re: Old DMM Failed Today
Post by: shakalnokturn on April 16, 2021, 05:40:56 am
If bad only on AC Volts / Amps check the few electrolytic capacitors around the TRMS converter.
Title: Re: Old DMM Failed Today
Post by: sarbog on April 17, 2021, 10:47:05 pm
Yes,  I will  test the electrolytics,    thanks.
Title: Re: Old DMM Failed Today
Post by: rsjsouza on April 17, 2021, 11:00:28 pm
You may also want to keep mr modemhead's page to give your meter an extra life...

http://mrmodemhead.com/blog/beckman-3020-dmm-repair/ (http://mrmodemhead.com/blog/beckman-3020-dmm-repair/)
Title: Re: Old DMM Failed Today
Post by: sarbog on April 18, 2021, 12:01:27 am
But,   still  want to buy the Dave  Jones    GW-121

Title: Re: Old DMM Failed Today
Post by: Nusa on April 18, 2021, 12:15:27 am
His BM786 meter is also a solid choice.

 Everyone who is serious about electronics ends up with multiple meters. Not considered a problem, so long as you don't spend the rent money.
Title: Re: Old DMM Failed Today
Post by: tautech on April 18, 2021, 12:21:54 am
His BM786 meter is also a solid better choice.
Sorta fixed that ^ for you.  ;)
Title: Re: Old DMM Failed Today
Post by: sarbog on April 18, 2021, 01:10:32 am
A  few   pics   of  my multimeters    since    1967,  a  Simpson  260,  a  Beckman  2020.......    I  have  repaired  both....   
Title: Re: Old DMM Failed Today
Post by: sarbog on April 18, 2021, 01:11:43 am
My  Beckman....
Title: Re: Old DMM Failed Today
Post by: sarbog on April 18, 2021, 01:52:30 am
Why  is it  better?
Title: Re: Old DMM Failed Today
Post by: sarbog on April 18, 2021, 02:09:35 am
Playing  with   the    design  from   Dennis   Hilll     about  a   digital   ESR meter ......         got  it    working      very    cool    stuff ........  Thank you  Dennis   Hill.....
Title: Re: Old DMM Failed Today
Post by: Michael YYZ on April 18, 2021, 02:19:19 am
I’ve got the same identical one, although mine is branded as Wavetek. Love it! It works perfectly well, except some plastic tabs broke off from the case and rotary button and now the latter spins 360 degrees. But fine, otherwise. I checked the True RMS measurement against my new Siglent SDS2104X Plus scope and obtained similar readings.

https://www.eevblog.com/forum/testgear/hantek-dso5102p-different-measures-when-changing-the-coupling-(ac-vs-dc)/msg3549957/#msg3549957 (https://www.eevblog.com/forum/testgear/hantek-dso5102p-different-measures-when-changing-the-coupling-(ac-vs-dc)/msg3549957/#msg3549957)

I hope you’ll be able to fix yours...

My  Beckman....
Title: Re: Old DMM Failed Today
Post by: tautech on April 18, 2021, 02:27:27 am
Why  is it  better?
https://www.youtube.com/watch?v=7AhypTCJOTE (https://www.youtube.com/watch?v=7AhypTCJOTE)

https://www.youtube.com/watch?v=UY9Myo5ngPQ (https://www.youtube.com/watch?v=UY9Myo5ngPQ)
Title: Re: Old DMM Failed Today
Post by: shakalnokturn on April 18, 2021, 04:02:53 pm
I used to own a Wavetek 2020 too, sold it in the end I had plenty more to hold on to, never got used the "menus" didn't like the feel of the function switch either.
Title: Re: Old DMM Failed Today
Post by: sarbog on April 30, 2021, 04:39:17 pm
My new EEVBlog DMM  arrived today...    very nice!

Title: Re: Old DMM Failed Today
Post by: sarbog on August 31, 2021, 12:39:22 am
Finally    got   around   to taking  my  old Beckman    Industrial   multimeter  apart....     model  2020   from  late  1980's.   It is  working   again  on    true  rms   ac  +  dc .       I   checked    a  lot  of  stuff,  could   not   find  any  special     true  rms chips  in it   with  a  microcontroller...    So  I   cleaned the   big    rotary   switch,  put  it  back  together     and   now  it   is  working..   very  cool.     Does   anyone   know   how  the   true   rms   circuit   is  implemented
?

Title: Re: Old DMM Failed Today
Post by: Tycho_Brahe on August 31, 2021, 01:14:09 am
A  few   pics   of  my multimeters    since    1967,  a  Simpson  260,  a  Beckman  2020.......    I  have  repaired  both....

Nice Simpson!   I have that same model meter that I got used recently.  I'm repairing mine now.  A 138 ohm resistor is open.  I suspect someone connected it up to some high voltage in resistance mode?   Not sure.   The Rx100 mode is the only range broken.  Afraid more components are bad, but starting with the one I know about.
Title: Re: Old DMM Failed Today
Post by: sarbog on August 31, 2021, 02:15:59 am
My  first    Simpson      260   I   damaged  in   high    school   about   1969...   cost    me    $200    for    repairs........    was  testing    high   voltage  on my   tube amp   ham  radio....