{"id":2311,"date":"2013-11-18T07:31:50","date_gmt":"2013-11-18T05:31:50","guid":{"rendered":"http:\/\/www.retro.co.za\/blog\/?p=2311"},"modified":"2015-03-17T19:40:38","modified_gmt":"2015-03-17T17:40:38","slug":"avo-model-9-mk-ii","status":"publish","type":"post","link":"http:\/\/www.retro.co.za\/blog\/?p=2311","title":{"rendered":"Avo Model 9 Mk II"},"content":{"rendered":"

My parents bought this Avometer for me at a boot sale when I was most likely still in primary school. It didn’t work, of course. But it’s a neat piece of kit.<\/p>\n

I remembered about it again the other day and went to find it in the attic where I do quite a bit of stowing<\/a>.<\/p>\n

\"\"<\/a><\/p>\n

A few decades worth of dirt.<\/p>\n

Some cleaning and some googling and…<\/p>\n

\"\"<\/a><\/p>\n

Hey! It’s a year older than I am (366 = March 1966).<\/p>\n

\"\"<\/a><\/p>\n

I’ve never even seen one of the 15V batteries for sale anywhere, so these batteries have been in here since before I got the meter. And most of the time I’ve had it was spent in a hot attic. The batteries are flat, of course, but I would have expected things to look a whole lot worse.<\/p>\n

Now I distinctly remember that I tried to find out what’s wrong with this meter, and at the time I concluded that the movement was not working. Well, it turns out that there’s nothing wrong with the movement. This is great news. Anything else is easier to fix than a d’Arsonval<\/a> movement.<\/p>\n

\"\"<\/a><\/p>\n

Here’s the damage. This is the 42.2 ohm resistor between the 10mA and 100mA taps on the DC switch (see the schematic at the end of the user manual<\/a>) and I would say that it’s maximum power rating was exceeded…<\/p>\n

I will see whether I can find or make or devise a replacement*, and I’ll clean up the outside.<\/p>\n

Please, if you have one of these, be nice to it, don’t gut the insides like this poepol did<\/a>.<\/p>\n

* Believe it or not, 42.2 Ohm is an E96 value<\/a>, but I might need a higher wattage and I’d probably end up putting ten 422 Ohm 1% resistors in parallel. Edit: Six 470 ohm, six 560 ohm, and one 4k7 in parallel makes 42.2065 which is good enough for me.<\/p>\n

(Edit: link to balancing the movement<\/a>)

My parents bought this Avometer for me at a boot sale when I was most likely still in primary school. It didn’t work, of course. But it’s a neat piece of kit. I remembered about it again the other day and went to find it in the attic where I do quite a bit of stowing. A few decades worth of dirt. Some cleaning and some googling and… Hey! It’s a year older than I am (366 = March 1966). I’ve never even seen one of the 15V batteries for sale anywhere, so these batteries have been in here since...<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[75,37,31],"tags":[],"class_list":["post-2311","post","type-post","status-publish","format-standard","hentry","category-electronics","category-farting-around","category-geek"],"_links":{"self":[{"href":"http:\/\/www.retro.co.za\/blog\/index.php?rest_route=\/wp\/v2\/posts\/2311","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.retro.co.za\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.retro.co.za\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.retro.co.za\/blog\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/www.retro.co.za\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2311"}],"version-history":[{"count":7,"href":"http:\/\/www.retro.co.za\/blog\/index.php?rest_route=\/wp\/v2\/posts\/2311\/revisions"}],"predecessor-version":[{"id":2319,"href":"http:\/\/www.retro.co.za\/blog\/index.php?rest_route=\/wp\/v2\/posts\/2311\/revisions\/2319"}],"wp:attachment":[{"href":"http:\/\/www.retro.co.za\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2311"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.retro.co.za\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2311"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.retro.co.za\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2311"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}