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My order of NOS Oldaker Leads, to match my favorite Oldaker modular test probes, which I bought on eBay stole for a $10 "Make Offer" arrived today. After dismantling one end of a lead to see what was under the molding, I decided to just build the leads with the "craptacular" 4mm banana plugs we were talking about the other day.

1- After soldering the spring and lead in place, I wrapped two full layers of cello tape around the threads to tighten them up; I figured if I was gonna tape it, the tape might as well serve a purpose. When I assembled, the ends got a good bite on 4-5 threads and feel pretty solid.

2 - Both ends presents a 90° threaded connector, meant for use evidently with probe, plug, alligator or jack; I've searched many times over the years, and evidently this is an Oldaker "thing". I've NEVER seen any Modular leads from Oldaker except the #537 & the #598, and they both expect you to use a 90° at the probe. I've seen straight leads on soldered-together probes, but not the modular sets.

3 - Here's what I got; 5 sets of vulcanized rubber 18ga leads in perfect NOS condition; not the least bit stiff or cracky, and not mallowy either. Just a joy in the hand. I also got 2 sets of BNC to Oldaker probe test leads, and a set of screw-on 4mm banana socket adapters. I've tried to use these before; they're too fat for shrouded plugs, and the bottoms have a rim that cracks out if you put them on the probes. I'm still trying to figure out  they were thinking there. All leads are old-school 48" long. 

4 - Once doctored up, the cheap-ass banana plugs actually seem half-decent; they plug in positively and smoothly with a good ~8mm of engagement, and they look like they belong on the 3478A. I'm no petite flower ("ham-fisted" is the term that comes to mind), so we'll just have to see how well they hold up under my tender ministrations. 

5 - In use: I had my reservations that the 90° angle at the probe would be annoying... it's why I haven't had a massive hard-on to buy the matching leads, and certainly not willing to pay the "collectible" price everybody seemed to want for them. But really it isn't that bad; having the lead draped across the back of my hand does bug me (I've been bit by ignition coils a few times using old-school automotive oscilloscopes), but as long as I turn the probe so the leads points away from my hand it doesn't bother me at all. And it seems it may even be a better arrangement to minimize capacitive/inductive coupling with my body during sensitive measurements. 

If you're wondering: from my testing so far, a shorting lead or shorted set of leads measures ~0.1400-0.1800Ω on this meter; so far, I haven't figured out how the "auto-zero" is supposed to work. I really need to read the manual rather than just skimming it like 6 times. 

So there you have it... one of the last pieces of the 3478A puzzle finally coming together... now all I need is a space deep enough to to be able to use it without it eating up half the workspace on my bench like it's doing here.   

mnem
Ahhh, sweet Hypnos' tender embrace...

New battery came in for the hp 8904A today. Per service manual instructions, wired up a temp 3V battery across C5. Removed and installed new battery. Note the original small plastic washer on Neg. lead to prevent the metal of the batt. terminal cutting into other traces.

Replaced board and we're back in business. 

Now waiting on new replacement IEC line filter. 

I really need to excavate mine from the rack, pop it open and check the battery.  It's probably due...

Thanks for the nice photos, xrunner.

-Pat

If you're wondering: from my testing so far, a shorting lead or shorted set of leads measures ~0.1400-0.1800Ω on this meter; so far, I haven't figured out how the "auto-zero" is supposed to work. I really need to read the manual rather than just skimming it like 6 times. 

Well, RTFM is a useful last resort, but that reading sounds about right and in this case I would simply use 4 bits of wire

The 3478A is calibrated for either 2-wire or 4-wire apparently. Depends on how the unit was set up to start with.

Too many variables for me to be happy about calibrating (cf zeroing) a 2 wire resistance measurement.

I'm liking my 8012A. You calibrate it by shorting the test leads then zeroing it out. Works pretty well and is cheaper and easier than dealing with kelvin connections and good enough. Gives 1mR resolution. It's good enough to trace board shorts out anyway.

I thought we were talking about measuring resistance, not radioactivity https://physics.nist.gov/cuu/Units/outside.html

Unicode support on this forum is shite. Ohms symbol (nice and easy to type on macOS - option+Z) rendered as the Unicode “square of fuck you”. Hence R. Boo hiss.

I expect LaTeX or at the very least MathML support on an engineering forum 

I spend half my day in MacTeX

There used to be a quirk with Unicode on SMF and I think you could set UTF-8 as an option but it may not be here?

edit yep still an option https://wiki.simplemachines.org/smf/UTF-8_Readme

This forum is very bare bones which isn't always a bad thing.

The forum I had to sort was brought forward from a custom build of the old version then rebuilt from there. There was plenty of times mods installed wouldn't port forward and weren't updated by their creators so I had to sort out their code at times which was messy trying to follow someone else work as well as not breaking the base code for SMF 

I really need to excavate mine from the rack, pop it open and check the battery.  It's probably due...

Thanks for the nice photos, xrunner.

-Pat

You should, you really should!  I'll remind you if we don't see it in a few weeks.

The thing is really long, but I think I have managed to make a place for it on the bench by creatively re-arranging a corner. Might even run a 10 MHz ext. reference to it (I did test that and it works well).

I couldn’t face using that dirty hack. It was like typing up your homework in the early 1980s. Oh dot matrix printer doesn’t print theta, just leave a space and write it in after 

My mother still has a selectric! She's got a perfectly good computer but likes that better because there are less distractions when she's writing to people.

Same reason I use MacTeX. Also weighs a lot less than a Selectric and the battery lasts longer

Edit: actually the battery on this thing is bloody amazing. 09:45 - 17:15 non-stop (bar 20 mins for a shit Pret) iTunes, python, iTerm/vim, Safari. No charge. Battery still on 44% 

Ohmmmmm Ω \$\Omega\$Ω \$\Omega\$Ω \$\Omega\$Ω \$\Omega\$Ω \$\Omega\$Ω

Sussed it I think. May hace been user error 

Quote from: tggzzz on December 11, 2018, 09:16:21 am

Quote from: mnementh on December 11, 2018, 05:42:51 am

If you're wondering: from my testing so far, a shorting lead or shorted set of leads measures ~0.1400-0.1800Ω on this meter; so far, I haven't figured out how the "auto-zero" is supposed to work. I really need to read the manual rather than just skimming it like 6 times. 

Well, RTFM is a useful last resort, but that reading sounds about right and in this case I would simply use 4 bits of wire

LOL... I'm totally snurching that.

While I know I AM resourceful enough to build a pair of "semi-kelvin" probes for this thing, that seems a bit convoluted just to get it to come close to zero. I figured the fact I couldn't find some equivalent of Δ or "zeroing" was simple user error. One of the grails I was seeking in the purchase of this unit was the 4-decimal resolution for locating shorts in a PCB.

Ah, that's  a chance to get a new class of test equipment, e.g. a Hytrak 100D. That is designed to measure low resistances (one range is up to 0.2 ). You don't even need to look at the display, since it emulates a mandrake by screaming at you.

Glider pilots have a very similar instrument, the audio variometer, which allows you to know how fast you are going up/down while still keeping an eye on those other aircraft which are (hopefully) a few hundred feet away.