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Test Equipment Anonymous (TEA) group therapy thread

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Cerebus:

--- Quote from: GerryBags on May 18, 2018, 07:35:19 pm ---
--- Quote from: Cerebus on May 18, 2018, 05:35:50 pm ---Not entirely. The resistance ranges can be knackered with the rest working fine. I don't know why, in principle there's nothing obviously wrong with the designs, but HP always had problems with the current sources on resistance ranges. If you've an HP34xx and everything's working perfectly except resistance then it's always the current sources. It's a stock fault for HP meters.

--- End quote ---

So.... if someone had just pulled the trigger on a 3455A that isn't working on the resistance ranges they wouldn't have just shot themselves in the foot, then?  :phew:

--- End quote ---

I wouldn't panic, they usually easily fixed as long as it isn't something dead inside a hybrid, and those faults are rare and often hit more than one thing. As it is, I *think* that the 3455 has only standard components in it. The only gotcha on the older meters is that if you've got a dead transistor that's only listed under an HP part number you can have fun figuring out what to replace it with.

med6753:

--- Quote from: Cerebus on May 18, 2018, 08:11:27 pm ---I wouldn't panic, they usually easily fixed as long as it isn't something dead inside a hybrid, and those faults are rare and often hit more than one thing. As it is, I *think* that the 3455 has only standard components in it. The only gotcha on the older meters is that if you've got a dead transistor that's only listed under an HP part number you can have fun figuring out what to replace it with.

--- End quote ---

Aren't there cross reference lists for HP transistors? I've been very successful in finding cross references for Tek transistor part numbers.

bd139:
http://www.sphere.bc.ca/download/hp_xref-free.pdf

GerryBags:

--- Quote from: med6753 on May 18, 2018, 08:03:57 pm ---
--- Quote from: Specmaster on May 18, 2018, 08:01:16 pm ---OT, I'm going to an evening air show tomorrow, is anyone interested in more aviation photos from it, I don't want wear anyone's patience by posting them here if they are not welcomed, it is after all an electronics forum  :-+

--- End quote ---

Yes, I'm interested.  :-+

--- End quote ---

Me, too. Even the old 'planes had some kind of electronics in them, so it counts in my book.

Thanks, Cerebus. I have the HP eqv. part list saved....somewhere. Downloaded from here.... somewhere. Aha! cheers, bd139, I'll save it in a few more places on my computer, just in case. I've downloaded the manual, but I've seen a paper copy for sale that I might grab. The scans are too low-res to see the numbers properly in the pdf and I find physical schematics much nice to work with.

I must remember NOT to send it to RS for a cal. It's hard to believe that nobody in that cal lab had the gumption to look the bloody thing up on online, even if they couldn't call up someone who'd know. You must be pretty miffed, Specmaster.

Cerebus:

--- Quote from: med6753 on May 18, 2018, 08:38:55 pm ---
--- Quote from: Cerebus on May 18, 2018, 08:11:27 pm ---I wouldn't panic, they usually easily fixed as long as it isn't something dead inside a hybrid, and those faults are rare and often hit more than one thing. As it is, I *think* that the 3455 has only standard components in it. The only gotcha on the older meters is that if you've got a dead transistor that's only listed under an HP part number you can have fun figuring out what to replace it with.

--- End quote ---

Aren't there cross reference lists for HP transistors? I've been very successful in finding cross references for Tek transistor part numbers.

--- End quote ---

Yes, but they're not as comprehensive as I'd like. Case in point, the JFETs used on the 3458A aren't all decoded yet. There's still thousands of parts on the list though, lest I sound too damning. The usual file name for this is hp_xref-<varies>.pdf.

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