Quote:
Originally Posted by technicolor
an update:.
Have the chassis out and going through it thoroughly, all three wax caps in this set were bad. And so far all three electrolytics were bad. Surprisingly, the one e cap, had a reading of 80uf, instead of the marked 50uf. I would assume when they got older they would drift lower.
My capitance meter is well worth the $16 i paid for it. Started yesterday checking resistors. ONmy digital multimeter, one reads 1, all all settings for ohms, does that mean it's shorted?
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On testing caps.... A capacitor gets is value based on how long it takes a steady current source to charge the two opposing plated on the cap.. Larger plate area would give a larger value..... Given that, while a carbon resistor, or wire resistor can change value up or down, I don't think anyone has ever seen a 50uf cap change to a 80uf cap. (for this value to actually happen, someone would have to add foil to each of the two plates...) As a cap dries out it can change resistance, or "open" lowering value..... But increasing value I pretty much think is impossible.... In this case, knowing how caps of that size are made, and how they behave, and in this specific case, knowing the test instrument most likely cost less than the replacement cap. I would say that meter was at fault. An easy way to check your test equipment it to test it against a few components that are known good, at the extremes, and center of what the meter is known to be able to test. 100uf to 30pf for example. use 3 caps at those ends, and one in the middle.
In each case while testing anything, there is some "expectation" of what you may get, outside of that, you have to wonder about readings you get on cheap testers...... Any testers for that matter....