Author Topic: GDM 8246 Cal Referance needed After an accidental deleted 5M Range [SOLVED]  (Read 251 times)

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Offline Labrat101

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  Hi All ,
I was wondering if any one has ever calibrated an INSTEK DGM 8246. Dual Display
I have the Full service Manual for the GDM 8245 which is supposed to be the same except for the interface plug.

I had a problem with the 20M range it was out by 3 or more meg .
 So I followed all the procedures as per the Manual only to find some were not good for my Model or Version  :palm:
All was going well I did the CL10 CL20  &  CL40    400m \$\Omega\$. Short Shunt
 Used the heavy short . and all was correct.
Then I only had to Cal the 20M range with a 9.90M \$\Omega\$.  (CL50)
It Calibrated and then I got distracted and Pushed the Auto/man without the shift to EXIT  :palm:
 It reset the 5M range out . and the 20M is F..K and reads 5meg with a 10Meg test resistor.
 The Manual said it requires a 3Meg \$\Omega\$ for the 5M range .. some how its wrong and now that range is out.
That was correct.  is messed up now.
 
Has any one ever calibrated one of these GDM 8246  need  1 to 4.9999M & 20M Ranges

 all the other ranges and voltages are correct its just the Meg Ohms  .

UPDATE ..  Assuming the Manual is correct and I have a slight different version.
                    There are a few miner  component differences from the schematic . to my board .
                All the voltages are spot on . except the 6.2v ref which reads 6.8v 
                 my board has the LM399 Precision Reference rather than the 6.2v zener
                The Meg ohm ranges were out of cal. when I got it S/H about 3 yrs back.
                only about 3  - 4 meg on  the 20m range.
   
            I really like this meter and did not want to spend $400 to get same quality     

   Any help would be More than welcome . Or suggestions on this problem

 Also I do have the Full Service Manual for these GDM 8245  If any one is interested .
« Last Edit: November 01, 2020, 09:47:35 pm by Labrat101 »
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Offline Labrat101

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Re: GDM 8246 Cal Referance needed After an accidental deleted 5M Range
« Reply #1 on: October 29, 2020, 06:08:02 pm »
Hi to any one who read this.

Problem Solved Thanks to Goodwill  Service contacted me .
 With the correct values .
 So all is Good .  :) :popcorn: :-+
"   All Started With A BIG Bang!! ... & Magic Smoke  " 
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Offline rob blue

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Hi Labrat101

What are the correct values?
 

Offline Labrat101

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Quote from: rob blue on Today at 12:14:00 am
Hi Labrat101

What are the correct values?

>These Values are for the DGM-8246 Only .
Warning Make sure you are in the 5Meg scale before doing this .
Or you will delete the other ranges and have to do the whole Cal again.


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