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FIELD   MULTIMETER   » EXACTA «



MULTIMETER    »  E X A C T A  «    Model 1-20    by   H.G.L.   (1970's)
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Has the same housing as the  »ULTRON«  Model  UM 201 E  from the 1960's
The  »ULTRON« / KOSMOS  has more ( & different ) DC  & AC Ranges,  e.g.
two more  ( 2.5 mA  & 25 mA )  AMP(DC)Ranges          (* see below ...)
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20 kΩ / Volt ( DC & AC )          2 Jewels           < Ri(I) = 4.5 kΩ >

   10 V / 50 V / 250 V / 1000 V ;    50 μA / 250 mA   DC Ranges
   10 V / 50 V / 250 V / 1000 V                       AC Ranges

    0 Ω  ...  60 kΩ  /  6 MΩ   with  1.5 V  »AA«  Battery

- 20 dB  ...  +22 dB  ( Output Measurements, see Manual )

R E M A R K S   &   R E S T O R A T I O N
=======================================================================
A friend ask me for help  and  repair.  He found this instrument on its
WASTE CONTAINER: It came in its original red box with instruction sheet
and its old bill from 1973 ( ATZERT RADIO, BERLIN = 38 DM ) - But there
was NO TEST CABLE SET included! A quick investigation showed: DCV & AMP
worked. But ACV showed only the HALF VALUE.  Decision was made:  "It is
worth to repair!" ... 
   
    The (Mini-)GRAETZ-RECTIFIER
    was defect and had to be
    replaced:
    Home-made with 4 DIODES ...

2nd Problem:  The LOWER OHM-RANGE was dead. A RESISTOR was burned out.
With trial-and-error we found the replacement value of 270 Ω ...

 

... Next Problem: No common plug fits into its sockets - We had to make
our own, out of ( sand-down until fitting ) copper-wires - Weeks later
we found the right probes on a FleaMarket tour ...

     

For expanding the AMP(DC)Ranges of the »EXACTA« ( eg. 5 / 50 / 500 mA )
have a look at the ...

     S+H_LAB_AMP_METER  &  Multimeter "Recycle-Project"

... how to build a  3-SHUNT-BLOCK  ...

       --------------------------------------
         SELECTOR  |  SHUNT  |    RANGE
       ======================================
           50 μA   |   50 Ω  |  0 ..   5 mA
                   |    5 Ω  |  0 ..  50 mA
       --------------------------------------
          250 mA   |    6 Ω  |  0 .. 500 mA
       --------------------------------------

     

Have a look at the  N E X T  VERSION:

     » 4-SHUNTS & 4-SERIALS BLOCK «

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(* see above)

I have SPECIAL MEMORIES
on this type multimeter:
I had the »ULTRON« Model
in my youth and bought
it because its CLEVER
INDUSTRIAL DESIGN!

Observe the DIFFERENCES!

1st I changed the
» OHMS ADJ « wiring,
because it was
in my opinion the
"WRONG DIRECTION"

- HA! -
My »EXACTA« has the
same "wrong" behaviour:
Must be changed too ...
My  »ULTRON«  was good as a "Hobby Instrument".  I exchanged it in 1970
into the precise ( Class 1 )  »CHINAGLIA« ...

impressum:
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© C.HAMANN      http://public.beuth-hochschule.de/~hamann      03/10/13