tag:blogger.com,1999:blog-26385730250380897.post1776105662715013208..comments2024-02-26T16:02:17.461-05:00Comments on Reading Jim Williams: Scope Sunday 5Doctor Analoghttp://www.blogger.com/profile/10331958951440669259noreply@blogger.comBlogger5125tag:blogger.com,1999:blog-26385730250380897.post-67949376689000876782021-05-05T20:04:26.382-04:002021-05-05T20:04:26.382-04:00I have a 511A that has been sitting for years. Don...I have a 511A that has been sitting for years. Don't need it. What is it worth? Chicago area. Anonymoushttps://www.blogger.com/profile/17636913486627672828noreply@blogger.comtag:blogger.com,1999:blog-26385730250380897.post-88862033040513905552011-12-04T09:47:49.587-05:002011-12-04T09:47:49.587-05:00It's nearly Christmas, so I feel odd posting a...It's nearly Christmas, so I feel odd posting a comment on a blog entry from back in the summer. Nevertheless, I was thinking of your experience with the impatient Craigslist seller this weekend as I brought up an HP 200CD I bought on E-bay. <br /><br />How would I apply power? My seller said it was from a "working environment." Still. . . . <br /><br />The possibility of shorts over time or crud accumulation in bad places are good reasons to go slowly. But the usual reason given for the Variac approach is to "form" capacitors that may not have seen a voltage in years. As I thought about that, it seemed to make sense for instruments with solid-state rectifiers. But vacuum-state rectifiers require a hot filament before they become something more than a big open circuit. Worse yet, the filament voltage is stepped down from the mains, while most power supply caps see a voltage that's stepped up. Doesn't this mean that even with the Variac ritual, the voltage on the supply caps is going to go from zero to a pretty large value suddenly at some point, rather than ramping up smoothly over time from zero?<br /><br />After that thought, I put on my headphones and snapped on the power switch. No tone. Damn! Busted! Then I had to laugh at myself as - after a few seconds - the tone appeared and drifted into stability. Vacuum-state! Things were slower in the '50s in more ways than one.<br /><br />Merry Christmas, all.Anson Wheallernoreply@blogger.comtag:blogger.com,1999:blog-26385730250380897.post-28577041054170687902011-08-18T13:39:16.497-04:002011-08-18T13:39:16.497-04:00Thanks for the anniversary wishes -- 65 years and ...Thanks for the anniversary wishes -- 65 years and going strong here at Tektronix! BTW, glad there were no sparks or smoke during the Craigslist pick up. Regards, Scope-Guru at Tektronix.Scope-Guru Tektronixhttp://www.tek.comnoreply@blogger.comtag:blogger.com,1999:blog-26385730250380897.post-67231046201420958272011-08-18T11:27:55.216-04:002011-08-18T11:27:55.216-04:00Oh, man, that breaks my heart.Oh, man, that breaks my heart.Doctor Analoghttps://www.blogger.com/profile/10331958951440669259noreply@blogger.comtag:blogger.com,1999:blog-26385730250380897.post-3647617483620239952011-08-17T13:20:15.296-04:002011-08-17T13:20:15.296-04:00To your question, I have a 1946 TV, a 1930's A...To your question, I have a 1946 TV, a 1930's Atwater Kent radio, and a<br />Tek 535A all were damaged by the sellers.Anonymousnoreply@blogger.com