On Aug 31, 2:34 am, micha...@aol.com wrote: > Just thought I would give warning on B7971 Tubes being sold on ebay.
There are lots of different attitudes among sellers of these tubes. Some are sold as tested with returns accepted if not working (sometimes by a member here, actually). Some are sold as untested with varying return policies (ranging from "none" to "only if cracked"). One recent auction seemed to imply a level of paranoia where the seller assumed that the buyer would return broken, different tubes (from some other source) and so no returns would be accepted. Over years of experience buying used electronics, there are only 3 grades: Tested, which means "we turned it on and anything we found unworking is unlikely to be detected by the buyer within the return period"; Untested, which means "we actually did try to test it, but it either partially / completely didn't work or we broke it trying to test it"; Refurbished, which means "we pulled some sleazy trick to make you think it is better than it is". An example of the latter was the common 80's / 90's scam of dropping running fans in dry cleaning fluid to knock off all the surface crud and make them look like new. Of course, after 100 hours of use or so, it became apparent that the fluid also removed any oil / grease in the bearings, rendering the fan useless. Back on the subject of B7971's, if you use my definitions as a starting point you'll be less likely to be disappointed, particularly if you buy from someone with at least a minimum return policy. Of nearly 100 B7971's I've purchased over the last 8 years or so (mostly on eBay) I've only had 2 duds. One had a single bad segment, while one had been destroyed by overcurrent (the foil strip between the pin and the anode mesh was completely vaporized, with the glass insulating sleeve from it rattling around inside the envelope). The seller had listed them as untested but in good mechanical condition. We came to an agreement for a refund of about 50% of the sale price, based on the completely dud tube. So I got 2 tubes to use to train people how to handle these tubes, and 2 sockets to use as pin straighteners. A number of the tubes I've received have had weak elements and/or partial cathode poisoning. These may have legitimately been missed by the seller, if they're running their test setup muxed at high current. In my application, they're direct-drive with PWM dimming, so I can see issues the sellers may have missed. I'be been able to restore almost all of mine to good operating condition. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
