EEVblog #718 - Keithley 2400 SMU Teardown

What's inside the Keithley 2400 Source Measure Unit?

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[jipihorn]

VR600 is the voltage reference. It is a 1N45749 6.4V zener, 5ppm/°C.

[steverobbins]

The schematic has some obvious errors.  For example, just above and to the left of the diode that connects to +36V there is a capacitor that obviously should be a resistor.  Also, the output is not shown.  And it's important to note that most of the supply rails have a "VF" suffix which stands for Voltage Follower, meaning that they track the output voltage.  For example, the +15VF rail will stay 15V above the output, as the output goes up and down.

[davesherman]

Former Keithley engineer, I used to work on these. VR600 is the A/D voltage reference zener. FYI, the Altera chip is a custom A/D which also routes serial data from the main micro to the range shift registers, analog muxes, and the DACs.

[Eken-Eken]

I wonder if the volt ref is made zener stile with the VR400 and VR401 as you can see at 16:04
They are put on holders and all away from the board while all others are flat on the board.
Together with the placement near high-end resisters and on the same height lengthwise to the volt reference test points.

[bogdanmishunin]

There's a SOT to the left of and below the PLD that is marked VR604 or something. May be it is the elusive reference :)

[dorota]

Another teardown, big thumbs up! GJ Dave

[gamershadow]

Thanks for the upload. I can't wait to watch it. Love your channel. 

[videocouk]

Back around 2001, myself and a mate bought a few of these which were the 2400LV variant (high voltage disabled). I soldered a set of diodes into each one to make them "proper" 2400 units and we sold them on. Kind of wish I had kept one though.

[bfrost]

Spot the cap that should be a resistor on the PA drawing!

[DjResR]

That "1097" chip near the Vref test pin seems to be connected to that pin by the trace. I also spotted 74HC4094 8-stage shift-and-store bus register.

[MrBuck]

Come on people, stop futzing, Tuesday, Wednesday, Thursday .
As long as we get a video, try doing Dave`s job and see how you do
Good on you Dave  thanks for the videos 

[maggotjoe]

Dear EEV Blog, Perhaps a you could tear down some musical keyboards analog synths or some pro audio equipment for a future tear down Video! 

[manuelgarciasanchez]

Hi, could i know the relays specifications? Relays k208 and k207. Thank you

[hodmt]

At 16:23 you see VR216 and VR217 SOT23s near the top left corner. Voltage references?

[DoubleDD]

I can't watch your HD because it's in 50Hz. My computer REALLY doesn't handle it well.

[nrdesign]

Had to measure an optocoupler circuit at work, but I had to do it manually... took nearly an hour to go through the voltage range in tiny steps, and the PSU's voltage knob was a 1-turn pot.

[airwood]

The discrete VR600 could be the ref voltage diode?

[PyroShim]

Why is the copper plane around the pld and its clock not solid, but has little cutouts?

[danweecc]

VR600 diode = voltage reference. Below the FPGA.

[yaghiyahbrenner]

Oh Yes!!!! Finally vie been waiting ages for this one. Thanks. SignalPath did a great video on the new model.