Agreed! I wanted to test the caps I’m pulling out just to see their condition. So far the Black Beauties are coming back with around 1uA of leakage @ 600V. What value is considered not accaptable?even with meters/instruments that test "current" indicators of good health (esr, capacitance, working
voltage, ripple current) you can have caps that are defective in the audio chain - random noise,
hiss, and static. my dh101 had several such caps that measured perfectly but once replaced,
the noise(s) disappeared. my second recap in 40 years.
I would replace all electrolytic caps if they are 15+ YO, sooner if the brands are less than
top shelf (British term).
Thanks for the Tips! I have ordered most of these parts from Jim McShane, who seems to be a wealth of knowledge on these. I have reviewed multiple threads and have to say this is a great place with wonderful members! It's pretty exciting going through Historical Audio Equipment.agree with @jlovda!
replace all the electrolytic caps, with newer ones. Black beauties and even Black gates
(anything "black" - green Nichicon Muse ESs are the new black - for spooky "black" backgrounds)
have been out of production for a while and will soon enter replacement phases due to age
(like knee, hip replacements, etc)
short list of abbreviated comments/notes
1. replace <4uf ecaps with (stacked) films of any material (esp tantalums)
2. use non-polars for signal-path decoupling (better sound AND prevents explosions)
3. use brand name ecaps for PS and add bypasses @1/10 or 1/100 values
4. do one-at-a-time (pull, measure old, get new, measure new, solder new in, test)
5. do not correct anything you think is a mistake (PCB stencil markings, schematic, parts list)
replace exactly as it was in the working unit. re-engineer if you are talented, knowledgeable,
experienced, etc
6 do not change values when replacing unless you document why.
7. resistors: replace with like kind (CC, CF, MF, etc) unless you want different house sound
there are hundreds of threads here on AK for all the above. reading a few will allow the
lightbulb to go on and light your future. return the favor to AK by documenting your journey
and especially if you get help from AKers.
LMAO!!! OK, that's one way to do itSomeone on this forum had a very good test for old electrolytic caps. Remove from equipment and toss into nearest trash can, if it makes a noise when it hits the bottom of the can, it's bad.
I kinda like that test.........
BillWojo
Ohh I will at least save mine just to have the original parts with the Amp. Not that I plan on ever selling it, but there's something about having the originally installed parts with the vintage gear. Better than Land Fill!@BillWojo - great idea!
mine is to save them all, id them and wait for the cap/burn-in deniers and have them
test any/all I have found defective (music not measurement) and start a billion dollar
company that IPOs in a week.
no takers.
The Chroma 11200 Tester is able to reliably test for leakage. Even the small .02uF caps. Not in CIrcuit mind you. http://www.chromausa.com/pdf/Br-11200-Leakage Current_IR Meter-032007.pdfThere is no way to test capacitors in circuit for functionality. Your LC meter will only measure the capacitance, and won't be able to test for shorts or leakage.
An ESR meter is the best available solution, and even it only provides a basic "go/no-go" test for electrolytic capacitors larger than 1 uF. It will not reliably test any electrolytics much smaller than that, and it's not useful for film caps, so it's not capable of testing coupling capacitors, for example.
The only really reliable test is to take the cap out of the circuit and test it using a dedicated capacitor tester, which will apply the full working DC voltage and measure any current leakage.