OldGuy Posted August 19, 2005 Share Posted August 19, 2005 Would appreciate if someone could post or tell me where I could get a schematic of my AA networks including part values. Thanks Quote Link to comment Share on other sites More sharing options...
BEC Posted August 19, 2005 Share Posted August 19, 2005 Here you go. Bob Quote Link to comment Share on other sites More sharing options...
OldGuy Posted August 19, 2005 Author Share Posted August 19, 2005 Thanks Bob. Will have to dig in and find a problem with one of them. Perhaps I should just do as suggested earlier and just replace the caps in both of my 76 units. Norm the old guy Quote Link to comment Share on other sites More sharing options...
BEC Posted August 19, 2005 Share Posted August 19, 2005 Norm, You should replace all the caps. After rebuilding a hundred or more sets of them, I have never found a cap I would consider completely good in any of them. Usually the capacitance is not too bad, but the ESR (equivalent series resistance) is pretty bad in all of them. I can fix you up with a nice set of caps like I use if you want. Bob Crites bobcrites@centurytel.net Quote Link to comment Share on other sites More sharing options...
jrt Posted August 22, 2005 Share Posted August 22, 2005 How does one go about measuring ESR? I've seen LCR meters-and I know I have seen at least one post (somewhere) on how to tell if a cap was out of spec, but for the life of me, I can't remember how to do the measurement. Thanks, Jason Quote Link to comment Share on other sites More sharing options...
BEC Posted August 22, 2005 Share Posted August 22, 2005 ---------------- On 8/22/2005 2:37:39 PM jrt wrote: How does one go about measuring ESR? I've seen LCR meters-and I know I have seen at least one post (somewhere) on how to tell if a cap was out of spec, but for the life of me, I can't remember how to do the measurement. Thanks, Jason ---------------- ESR is a measure of the resistive component of a capacitor. All capacitors have some of this resistive component but a new good one will read down in the hundredths of an ohm. ESR increases as the capacitor ages and is just like having a resistor of the ESR value in series with the capacitor. Some meters can measure it directly like the one in the link below. It is a bit expensive and I think all that can measure ESR are on the expensive side. I think ESR can be calcluated by knowing several other hard to measure qualities. http://www.elexp.com/tst_k885.htm Bob Crites Quote Link to comment Share on other sites More sharing options...
jrt Posted August 22, 2005 Share Posted August 22, 2005 I have a couple of really old capacitors at home as well as a multimeter that measures capacitance (and resistance of course). I'll check some of them and see how they measure. I'd like to figger a way of testing a capacitor without spending a gob of money on a new tool....much as I like tools. Thanks for the info- Jason Quote Link to comment Share on other sites More sharing options...
BEC Posted August 22, 2005 Share Posted August 22, 2005 ---------------- On 8/22/2005 5:37:20 PM jrt wrote: I have a couple of really old capacitors at home as well as a multimeter that measures capacitance (and resistance of course). I'll check some of them and see how they measure. I'd like to figger a way of testing a capacitor without spending a gob of money on a new tool....much as I like tools. Thanks for the info- Jason ---------------- You can measure capacitance but not ESR without a specifically made piece of test equipment to measure ESR. The resistance range of the multimeter will not tell you anything about ESR. Bob Quote Link to comment Share on other sites More sharing options...
jrt Posted August 23, 2005 Share Posted August 23, 2005 Gotcha. From what I've gleaned, ESR is a function of frequency, so a DC source won't work for the test measurement. Is that close to correct? BTW- thanks for your patience. I've got decades of education, but none of it has been electronics! Quote Link to comment Share on other sites More sharing options...
OldGuy Posted August 31, 2005 Author Share Posted August 31, 2005 As I asked for the AA schematic because one of my Klipschorns was sounding a bit tired I spent a while going back and reading the old posts back to 2002 on crossovers and capacitores, WOW. Lots of feelings. Anyway I bought an ESR meter and had a great time. I forgot how darn heavy these horns are to move around. Anyway the ESR on the old oil capacitors where all beow 1.0 ohm. Physically they looked great, no leaks etc. I got out the capacity meter and all looked good. So back to basics. This I should have done before buying the ESR meter. Anyway I checked the resistance of the drivers all nominal. Just took all connections apart, cleaned and tightened everything and fired up the amp. Great sound again out of both speakers and I did not replace any parts. I hope this does not make people think changing to new caps or upgrading from the PWK designed crossover is not a good idea. But I do hope it points out that there are paths to try before changing parts. Quote Link to comment Share on other sites More sharing options...
BEC Posted August 31, 2005 Share Posted August 31, 2005 A good ESR reading would have been around 0.02 ohms. Yours are pretty bad at 1 ohm. Look at it this way, you have two of those caps in series with the tweeter. The tweeter is rated at 8 ohms. The 2 ohms in series with that gives you about a 20 percent loss of signal to the tweeter which is dissipated as heat in the caps. You need to replace those caps. Your Khorns can sound lots better. Bob Crites Quote Link to comment Share on other sites More sharing options...
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