DSE ESR meter.

Since getting hold of one of these kits and putting it to use, I've been getting the impression that modern electrolytics are manufactured with much lower ESR than was anticipated when the meter was designed and now I suspect that electrolytics with ESR values approaching the values in the table printed on the front panel might cause problems in modern fast switching PSUs.

Is there a revised table I can print out and stick over the old one?

TIA.

Reply to
ian field
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Those values were for a "worst case" value for those capacitances. I was under the impression that they were derived from cheap and nasty electros similar to "Joe Master" brand that DSE are so fond of stocking.

Reply to
Mark Harriss

On 7/02/2008 04:06 ian field wrote:

The charts on the front of the Mk1 and Mk2 ESR meters were only ever meant as a rough guide to what to expect until the user gets familiar with using the meters in real-world repairs. The Mk1 meter's chart was derived from an old capacitor catalogue, and the Mk2 meter's chart was the end result of me measuring a big pile of unused electrolytic caps and averaging out the values as best I could. The figures were all over the place. The Mk2 meter chart in text form is at

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Except in very rare cases, the ESR of an electrolytic cap which is causing problems will be found to be >10 times what the charts say, more often >30 times or above 99 ohms (the meter's maximum reading). There's only one repair situation I know of where ESR is critical - in one capacitor in one type of switching power supply which is sometimes found in older Sanyo, Teac and a few other TVs. An electrolytic cap which is usually about 47uF/25V connects from the base of the switching transistor to the collector of a control transistor, allowing the control transistor to progressively short out the switching transistor's base drive and control the output voltage. When that cap develops an ESR of maybe 10 ohms or more, the power supply loses regulation and the main B+ rail goes higher and higher, taking out a lot of circuitry and sending the EHT very high. It's a really stupid fail-UNsafe design. I hope this might have clarified things a little bit.

BTW ... has anyone here bought one of the Altronics ESR meter kits yet? If so, I'd like some constructor comments because I've never seen one. :(

Cheers Bob

Reply to
Bob Parker

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