Re: Clean and Lubricate Pots in Tek 475


 

Bill,

I had a closer look at the vertical input board and it looks like it might come out with less work than I thought. I haven't verified this, but it looks like the BNC connectors might not be mounted to the front panel (I thought I read a blog entry about repairing a 475 that said something about this, but I can't it now, however this post of EEVBlog shows a full teardown, which seem to support my hypothesis <https://www.eevblog.com/forum/projects/tektronix-465-repair-and-restoration/>). If that's true, then getting at the two vertical position pots is much easier (if not quite trivial). I also noticed that the only pots that got stiff are the "double stack" ones. The single stack, which appear to be from the same manufacturer, are all easy to turn.

It looks like I can buy replacements for between $10-$20 per pot, which I think is a fine price. If I can get the vertical input and main boards out without too much fuss, and if just lubricating them doesn't help, then I will just replace them.

I'm not sure who made these pots, but all of them (with the possible exception of the two trigger level pots, which are metal cans rather than plastic blocks) are brown/black plastic with dark red inserts. The replacements I've found online (from talonelectronic.com and rshopboss.com) are blue, and my scope was assembled in late 1974, so I'm assuming that it has A&B pots.

I have been very happy with the results I've gotten so far with what I consider fairly minimal effort: I only had to break out the soldering iron ONCE on this old thing, and that was completely unavoidable; to replace a obviously very dead electrolytic capacitor on the sweep board.

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