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From: Bill Sloman <bill.sloman@ieee.org>
Newsgroups: sci.electronics.design,sci.electronics.repair
Subject: Re: Favourite Test Equipment
Date: Fri, 12 Apr 2024 15:32:33 +1000
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On 12/04/2024 5:42 am, Phil Hobbs wrote:
> On 2024-04-11 13:11, john larkin wrote:
>> On Thu, 11 Apr 2024 09:55:18 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
>>> On 2024-04-10 16:30, Trevor Wilson wrote:
>>>> On 11/04/2024 3:42 am, Cursitor Doom wrote:
>>>>> On Wed, 10 Apr 2024 11:40:02 +1000, Trevor Wilson <trevor@rageaudio.com.au> wrote:
>>>>>> On 1/04/2024 4:41 am, Cursitor Doom wrote:
>>>>>>> Hi all,
>>>>>>>
>>>>>>> I'm starting to get a bit fed up with having my test equipment blow up
>>>>>>> just when it's needed. This is the drawback with vintage gear; if 
>>>>>>> it's not used frequently then it can go *bang* the next time you 
>>>>>>> switch it on. It makes for good practice in repairing stuff, but wastes a 
>>>>>>> lot of time which could be better spent doing other things.
>>>>>>> I think it's time I modernised my test gear. I was just wondering if
>>>>>>> anyone has any recommendations they can share. Is there a particular
>>>>>>> piece of test equipment you couldn't live without? Something you're
>>>>>>> particularly impressed with? I'd be interested to know so I can
>>>>>>> perhaps acquire said item and thereby reduce the number of 
>>>>>>> explosion I experience.
>>>>>>
>>>>>> **In my 55 years of servicing, I've only blown up one thing: A 
>>>>>> Micronta DMM, which I connected to a laser power supply. I should not have 
>>>>>> done it. Clear operator failure. Everything else works just fine. Even my
>>>>>> first multimeter. A Sanwa U-50D my dad gave me on my 14th birthday.
>>>>>> Still works fine. My first DMM. A cheap 'n cheerful SOAR. Works just
>>>>>> fine. My first Fluke meter. A 40 year old Fluke 85. Works fine.  I've had
>>>>>> to clean the switch a few times. Otherwise, no problems. Ditto my 
>>>>>> other 15 or so meters. Same deal with my 'scopes.
>>>>>>
>>>>>> I don't know what your problem is. Test equipment, when treated 
>>>>>> properly lasts a long time.
>>>>>
>>>>> To be fair, these "explosions" are typically capacitors: old, dried
>>>>> -out electrolytics in test gear that hasn't been used in a long time
>>>>> go bang when the power's switched on - as do old X2 safety caps. Those
>>>>> are the chief culprits IME.
>>>>
>>>> **Oh, I see. You ignore regular maintenance. That makes sense. I 
>>>> hope no-one buys a car from you.
>>>
>>> Whereas all you Ozites are 100% rational reasonable polite beings who
>>> are always on top of everything, including predicting the exact date
>>> when an old cap will give up the ghost.

Old electrolytic capacitors tend to give up the ghost when they have 
been left unpolarised for years, and are then subject to their rated 
voltage without having been re-formed first.

Predicting that kind of failure isn't difficult.

>>> Silly me for forgetting. ;)

You don't have much to do with clueless newbies.

>> You don't routinely replace caps in all your test gear? I'm shocked,
>> shocked.

You don't replace them, you re-form them -  day or so subject to rated 
voltage applied through a nice big resistor (100k comes to mind).

> Sad but true. ;)
>
>> (My nice little HP6212A power supply must be 50 years old. It's never
>> been opened and works great.)
> 
> I have a number of the 611x supplies, including the 3 kV one.  Only one 
> has ever actually failed--it was my previous 3 kV, whose transformer 
> started arcing internally, so I tossed it.
> 
> In good equipment (HP & Tek, 1985 or so on), age-related failures are 
> much more common on the outside of the front panel than on the inside. 
> (A problem not unrelated to PEBCAK.) ;)

Problem Exists Between Chair and Keyboard.

-- 
Bill Sloman, Sydney