VTVM resistors

[Charles W. Morehouse]

Hi Ron,
Looking at the IM-13 schematic and can't find any values such as 21.62K
or 68.38K values.  The resistors are all even values.  Probably only one
is bad.  Locate that one.  Mouser has most of the values or ones very
close in 1%.  Be sure to check or replace the high values resistors in
the circuit.  If you still have problems, I can send you the range
switch from a V-7A.  All VTVM's were the same.  The resistors all check
good.  $15 plus postage.  The IM-13 is my everyday bench meter.
Try and find that bad one.  Is the meter inaccurate on all ranges or
only after say the 50 volt range. That is a big clue. Is it accurate on
ohms?  Good luck and 73's.
Wayne;
W4GBW

Ron wrote:

>I recently picked up an IM-13 bench VTVM (the one with the
>large meter). After some dusting and cleaning it looks
>fabulous -- almost like new. The only problem is that it's
>grossly inaccurate. One reason are the scaling resistors,
>some of which are way off their 1% rating. These resistors
>have non-standard values and were probably made specifically
>for VTVMs; possibly, specifically for Heathkit. Does anyone
>know where (and if) they are available?
>
>Specifically, I need 90 Ohm to 9M in all multipliers (that is,
>90, 900, 9K, etc.), 21.62K to 2.162M in all multipliers and
>68.38K to 6.838M in all multipliers.
>
>TIA,
>
>-- Ron
>
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