Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Bill Sloman Newsgroups: sci.electronics.design,sci.electronics.repair Subject: Re: Favourite Test Equipment Date: Fri, 12 Apr 2024 17:39:14 +1000 Organization: A noiseless patient Spider Lines: 94 Message-ID: References: <9k7j0jlnbhs8qfg5m17pium0835meean83@4ax.com> <24979c04-3d96-6fdb-1763-e1a6f9f0a6d1@electrooptical.net> <1fe9efa7-ea1a-7579-88ac-543ce48ff46e@electrooptical.net> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Fri, 12 Apr 2024 09:39:28 +0200 (CEST) Injection-Info: dont-email.me; posting-host="e94974f6c58031e44597f5cccf7b88a7"; logging-data="2358956"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1/OQcaE4Zirxm98WG51HnCAn8IWoGfGfLA=" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:tT7mepfSnt1muPmURrVr18PSRKU= In-Reply-To: Content-Language: en-US Bytes: 5805 On 12/04/2024 3:46 pm, Trevor Wilson wrote: > 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. The only time I've done it was with a "new" capacitor bought from a cheap supplier for my home-brew hi-fi. It was a large - it not all that expensive - component, and would have been a pest to replace. The hi-fi worked for about thirty years. It had sat in basement for quite a while - my wife eventually judged it too ugly for the living room - and when it stopped working it was quicker to buy an off the shelf replacement, and we then had the money to do that without thinking about it. I did think about finding the fault (in the discrete input transistors) but never got far enough to find the actual defective part or replace it. -- Bill Sloman, Sydney