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Old 26th Jul 2010, 6:19 pm   #36
Kat Manton
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Join Date: Jul 2005
Location: West Yorkshire, UK.
Posts: 1,700
Default Re: Test equipment for valve radio repair

Hi,

I'll add what's arguably a 'nice to have' to the list.

I was going to design/build a capacitor leakage tester with several selectable voltages, basically a high-voltage meg-ohm meter, until I discovered a device already existed which does exactly that.

I'd always assumed that insulation testers (usually 'Megger' though there are others) used a fixed voltage, often too high (500V) for capacitor leakage testing.

Then I encountered the Megger BM8/2 - a multi-voltage insulation tester. It's analogue, battery-operated, the internal circuitry is fairly simple (so should be repairable); measures resistance at selectable voltages with ranges as follows:
  • 0 to 1,000MΩ at 50V
  • 0 to 2,000MΩ at 100V
  • 0 to 5,000MΩ at 250V
  • 0 to 10,000MΩ at 500V
  • 0 to 20,000MΩ at 1000V
(All ranges include infinity of course; the above are the limits of what can be measured on the meter's scale.)

This looks much more useful than a fixed-voltage tester; one of those "why didn't anyone tell me these things existed sooner?" bits of test gear!

They're not particularly expensive as they've been superceded by a digital version, seem to be fairly common and turn up second-hand often enough.

I've just bought one (though I wouldn't class it as 'essential'; in-circuit measurements, substitution and 'on-sight' replacement of certain types have served adequately well so far.) But, given the amount of faulty vintage electronic hardware I've accumulated, anything which helps identify faulty components more readily means I might get more of it working!

Regards, Kat
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