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HP 11683A Range Calibrator - Anyone ever swapped resistors for a repair?

 

Hey All,
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I dropped my 11683A Range Calibrator on the bench to test some 435A meters, and I've discovered that it is out of specification.
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Here is what I measured on the device:
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The lower level resistances are good, and my overall reference voltage is close to 15.8V (and can be adjusted to the 145mV as the manual specifies for the 1mW range). However, as you can see it fails the greater 1mW ranges, which I think indicates that there is a problem in the upper resistor array and this, again as far as I can tell, makes the voltage measurement stuff a bit dodgy.
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Does anyone have any recommendations on replacement resistors? The manual says a 0.1% with TC=0 +/- 10, the OEM was Micro-Ohm Corp of CA.
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Thanks,
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TonyG
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Hi Tony,

There are some companies that can make custom laser trimmed resistors but I cannot find it my notes now. I heard that Vishay can also take an order for custom resistors but I guess you need to order a big batch.

Best regards,
Razvan

On 02/05/2025 21:25, Tony Goodhew via groups.io wrote:
Hey All,
I dropped my 11683A Range Calibrator on the bench to test some 435A meters, and I've discovered that it is out of specification.
Here is what I measured on the device:
The lower level resistances are good, and my overall reference voltage is close to 15.8V (and can be adjusted to the 145mV as the manual specifies for the 1mW range). However, as you can see it fails the greater 1mW ranges, which I think indicates that there is a problem in the upper resistor array and this, again as far as I can tell, makes the voltage measurement stuff a bit dodgy.
Does anyone have any recommendations on replacement resistors? The manual says a 0.1% with TC=0 +/- 10, the OEM was Micro-Ohm Corp of CA.
Thanks,
TonyG
_._,_._,_
 

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Tony, when I checked mine I found it was very sensitive to the measuring DVM's input resistance which needs to be very high, details are in the manual, and I thought at first that I did need some new resistors, but it was my measuring that was at fault.

There is a company in Texas that makes Rs of the spec needed, from memory about $16 each, if you do need any.

Dan
 

Thanks Dan & Razvan,
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I did indeed have my DMM set to 10M instead of 10G - Changing that puts everything back into spec:
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Thanks for the help,
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TonyG
 

Read the ¡°structions¡± first ?as Harpah would say!
Dad

On Sat, 3 May 2025 at 8:19 am, Tony Goodhew via <tony_goodhew=[email protected]> wrote:
Thanks Dan & Razvan,
?
I did indeed have my DMM set to 10M instead of 10G - Changing that puts everything back into spec:
?
?
Thanks for the help,
?
TonyG

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