XPost: sci.electronics.design   
   From: trevor@rageaudio.com.au   
      
   On 12/04/2024 3:32 pm, Bill Sloman wrote:   
   > 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   
   >>>  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   
   >>>>>>  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).   
      
   **It would only be required if the unit has been out of service for   
   quite some time, unless it is very old of course. In any case, if I   
   remove a cap from equipment, it will almost always be simply replaced,   
   unless it is a very large and expensive component.   
      
   >   
   >> 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.   
   >   
      
      
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