Short repair Keithley 2000 ERR500.2

[hwj-d]

Hoy 

last year, im lucky to get one nice 96's K2000 for massive under 300€ from the bay here in germany. I'm quite happy with it. 

By the way,
still to rely on it, i bought a brand new 34461a, lookin now to some expensive Vishay's plus something like xDevs's KX Voltage reference. What do you call this? Addict for what?
OK, the most things i can will do, i want to make it by myself, still in hope to learn something...

Now, the K2000 is ok, but it couldn't measure 4W. Selftest are all ok, but with ERR-500.2 (4W SENSE).
After studying Repair-Manual and this outstanding assistance extern schematics (big, big thanks to the person who made this reverse engineering), i realized, that Sense-HI is permanently at +15V.

Some measurements show, that there is a little black dot, a JFet-Transistor (Q107), that don't ask me to give the 15V to Sense-Hi. 
After 20 years, i have punished him, to go out of my DMM, and lo and behold, my DMM is doing his job also with 4W, the error is gone. Although not replaced with another one for now, till i have one.

My question for now:

• is this JFET like a fuse, for stupid people like me (but don't do it), they stick the big power in this little sense-bindingpost?
  (Edit: don't think it the wrong way...) 
• is it like a pullup?

Maybe, it could be a nice theme for Dave, to explain this excellent range- and error-switching concepts along with this dmm?

Thanks to all,
H.-W.

Edit: orthography

[hwj-d]

The Art of DMM 

[onesixright]

nice pics!

lens ? aperture?

[hwj-d]

nice pics!

lens ? aperture?

FUJIFILM X100S
23.0mm Solid Lens 1:2.0
mostly ƒ/5.6 0.0080s(1/125)

I had several APS-C Mirror-Reflex-Cameras
but this is comparatively so outstanding and compact, that i sold nearly all my other gear.

[onesixright]

nice pics!

lens ? aperture?

FUJIFILM X100S
23.0mm Solid Lens 1:2.0
mostly ƒ/5.6 0.0080s(1/125)

I had several APS-C Mirror-Reflex-Cameras
but this is comparatively so outstanding and compact, that i sold nearly all my other gear.

Thanks!

I love the low "level" shots (can be lower  ) , maybe close it down 1-2 stops (for a tad more DOF)?

PCB's makes a nice subject 

[hwj-d]

PCB's makes a nice subject 

Sometimes they are really sexy, like "sex-on-a-stick ..." 

[z01z]

My question for now:

• is this JFET like a fuse, for stupid people like me (but don't do it), they stick the big power in this little sense-bindingpost?
  (Edit: don't think it the wrong way...) 
• is it like a pullup?

hography

Sorry to go off-topic  .

It acts a low leakage diode.
Have a look at this book.
There's also a TI appnote.

[hwj-d]

Sorry to go off-topic  .

You bring it back.

It acts a low leakage diode.
Have a look at this book.
There's also a TI appnote.

Many thanks for this info!

[TiN]

Nice work both on pics and fix 

[hwj-d]

Nice work both on pics and fix 

Thanks TiN for your feedback.

As i mentioned, i'm lurking to your very nice (KX-) Voltage references to build it by myself. But don't know for now, what i really need. The precision or cheaper one. At times I come back to it

[hwj-d]

To complete it,

this ominous defective transistor (Q107), be found at many places on my board top marked "132", others have "6G", repairmanual says it's a SNJ132199, under this designation isn't searchable.

Anyway, this is a JFET N-CH 30V 0.225W SOT23 MMBF4393LT1 standard component, available by many distributors.

[JoeO]

nice pics!

lens ? aperture?

Download the picture.
Right click and select properties.
Click on the details tab.
Scroll down for the properties.

[hwj-d]

nice pics!

lens ? aperture?

Download the picture.
Right click and select properties.
Click on the details tab.
Scroll down for the properties.

Yes, the Exif-Data are inside pictures. I left them there.
There are several plugins for current browsers, to see them directly.