Electronics > Repair
Keithley 2000 TF-245 version / year question
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Overspeed:

--- Quote from: Kleinstein on May 13, 2024, 07:37:10 am ---The Cadock ceramic networks that are used for high voltage dividers are usually thick film and thus not super stable. They are special to withstand high voltages, but for low voltage more normal thin film types would be preferable.

Chances are there would be more space available, possibly a vertical mounted PCB.



--- End quote ---

Hello

I agree , my remark was more on the size room on the board compare to the soic 16 broad

I check the vertical solution PCB , my first concern is to limit as possible force on the SOIC solder tab

Question : As the Keithley board have a stiif aluminium hood with a 4 mm pillar on the front , Do you think that could be possible to extend this hood as a PCB support and link the SOIC foot print with wires ? The aim will be to avoid mechanical stress on the small SOIC solder tab and also allow to install real resistors net without room limitation.

Regards
OS
Kleinstein:
The mechanical stress could be indeed limiting. It should still be OK for normal use, but shipping it (e.g. for calibration) could become an issue.

Using wires and an edditional external PCB could work, though it adds a little copper resistance. The ref. amplification for some reason uses a rather fast amplifier but should be OK with the relatively large capacitors.
Still the extra capacitance is not great - so the cable should not be long.
Overspeed:

--- Quote from: Kleinstein on May 13, 2024, 09:29:36 am ---The mechanical stress could be indeed limiting. It should still be OK for normal use, but shipping it (e.g. for calibration) could become an issue.

Using wires and an edditional external PCB could work, though it adds a little copper resistance. The ref. amplification for some reason uses a rather fast amplifier but should be OK with the relatively large capacitors.
Still the extra capacitance is not great - so the cable should not be long.

--- End quote ---

Hello

Could be possible to install a plate like the white page on the picture
Wiring will be less that 40 mm long as the resistor PCB will be on the top of the 245 foot print

If other people are interested I can laser cut some and propose kits after final design testing

Regards
OS
Kleinstein:
The screws close to the rear side are likely not suitable, as they would be at or near the ground / outputside potential. The hood screw position does not look that bad. 60-100 mm of cable would likely be acceptable from the capacitance. For holding the PCB could likely extend to the screw area. The first point is seeing if the meter is working at all with modified resistors.

Overspeed:

--- Quote from: Kleinstein on May 13, 2024, 12:14:22 pm ---The screws close to the rear side are likely not suitable, as they would be at or near the ground / outputside potential. The hood screw position does not look that bad. 60-100 mm of cable would likely be acceptable from the capacitance. For holding the PCB could likely extend to the screw area. The first point is seeing if the meter is working at all with modified resistors.

--- End quote ---

Hello

I agree
As my 2000 ( this one ) is dead right now and I have also a 2700 with problems , I can built a prototype and test various circuits / components to see to result . accurate resistor are easy to locate when they are bigger too , Vishay foil as example

I will post progress

Mouser have 0603 and 0805 in 0.05% 10ppm SMD that quite cheap as under 1 Euro per unit and enough to make first test

Regards
OS
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