EEVblog #461 - Genrad Decade Resistance Box Teardown

Dave's Ignite Video:
Teardown Tuesday
How interesting can a box with switches and resistors be?
Not very? How about a multi thousand dollar Genrad 1433 metrology grade decade resistance box?

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[ikocheratcr]

At around 17:00 where you talk about the .1ohm metal strip resistor decade, I think they are not burned for calibration, I think some previous genius user just passed too much current thru them. If this resistor is .1ohm, and the rest of the circuit is < .01ohm, a high current will for sure damage it, leaving the rest unaffected.

[CoolMusicToMyEars]

The resistance Flat is Manganin (CuMn12Ni) or Zerranin which is ultra stable with temperature, the resistors will be varnish dipped or some companies used Shallac to coat their resistors, Don't use Silicone or expect the wires to fail after time !
IF you look inside a Cropico or Sullivan Resistance Box's then you know that you have a great Resistor Box :)
The darker resistance shows you it's been overloaded for sure on the very low range ! that's what happens to manganin when people overload it !,
Retired UKAS manager of a Electrical Standards Laboratory, over 43 years exp,
Resistance wire Look at a company called isabellenhotte, Heusler GMBH KG Dillenburg Germany :)

[martinda]

If you ever look this far back Dave? The wiring is almost definitely solid silver, not plated. Silver was demoted from precious metal status some time ago and is fairly cheap. Loved this, those switches are like the ones in my old AVO.

[andreww]

I use the IET RS-201W at school. Actually three of them at a time. Didn't know they were that expensive...

[karinyafields]

As an apprentice I used to re tip large circuit breakers. All contactors and switches that I worked had contacts made from Silver cadmium alloy.

[kostaskritsilas]

Quad Tech at one time had bought the Genrad/General Radio R:C bridges (165X/168X series) and other metrology/component measurement line. Some time after that, it all ended up with IET.

[EEVblog]

It's two resistors in the box. Part numbers are on the front.

[douro]

Vishay bought Dale a few years back...they inherited what is probably the best precision resistance design team in the world...

[SwitchingPower]

The replacement switch looks like an multi-tech industries model 820 "Test Equipment Grade Switch" i used before, they cost around $100 for one single deck switch.

[EEVblog]

Yes, very distinct possibility they were hand picked.

[gamccoy]

Good video! I love the fact that interesting detail hides in all sorts of corners of the world.

[RyanVasquez]

Only the best! Heck, i sat all the way through! I love it! i don't know why, i watch more of him than i do of actual TV shows, plus i learn a HELL OF LOT MORE

[dansanger]

Tellurium copper sounds almost as schmick as gold-pressed latinum.

[enginerdy]

I counted 84 wires on the 10k element..
btw, nice camera!

[JimGriffOne]

Hi Dave, do you think one of those Gold plating kits off eBay might be good to use on electronic contacts? I was thinking about getting one, but not sure if they're useless or not. Perhaps the Gold plating on electronics needs to be much thicker.

[FXGreggan.]

Only Dave can make a 35min video about a resistor decade :)

[Gringo_In_Chile]

Hi Dave,
Great hack! 2 things.
1) At 19:25 you say that you were going to link the page pages that you were browsing and did not. Please do.
2) Could you tell that the replaced selector switch felt different from all the rest before opening it up?

[fullwaverecked]

I'm not sure it's legal to have this much fun watching an electronics video?

[AngDavies]

I guess having loads of turns of lower resistance wire makes it easier to calibrate?

[ChipGuy]

I would never have guessed that a box of switches and resistors can be so interesting inside, Thumbs up !