Drop a pinch or 2 of any kind of powder on the surface, if it dissipates instantly when the switch is turned on, it's working. They make a racket when they are working, but most operate at 40 KHz, so the sound a human can hear is not a good indicator. Once in awhile they are found at yard sales. Test them on the spot and offer $5 for it. Most people don't have any idea what they are, so the chances are that the first offer will be accepted. Worth every penny-I use mine for cleaning flux off the boards, even the non water soluble flux is removed fast. Your local jewelers shop will have one, they get big bucks for cleaning jewelry in them-but they never reveal how it is done to the paying customer>>: Art >From: Adam Field >Date: 2008/06/11 Wed PM 03:20:22 CDT >To: "Microcontroller discussion list - Public." >Subject: Re: [BUY] Solder paste in a syringe >I come across ultrasonic cleaners occasionally, but I don't know how they >feel or look while operating. How do you check them for operation? I know >you can't run them dry. > >On Wed, Jun 11, 2008 at 1:19 PM, Artie Jones wrote: > >> When it begins to show >> signs of not working well, fill the ultrasonic bath with tap water, >> and drop the syringe in-needle and all. I used that sample from EFD >> for 8 years, with no special treatment other than the ultrasonic bath >> from time to time. >> >> As far as I know, EFD still offers teh same enormous sized 'sample' >> for free, although I haven't re-ordered yet. >> >> Enjoy. >> >> Art >> >-- >http://www.piclist.com PIC/SX FAQ & list archive >View/change your membership options at >http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist