21 Feb
2015
21 Feb
'15
10:42 a.m.
On 2/21/2015 1:33 PM, Robert Jarratt wrote:
I have been desoldering and checking
all the electrolytics. I have set each
one up on my bench PSU with the
current limiter set, and taking them
up to their rated voltage, or as near
as I could because some are rated 50V
and my bench PSU only reaches 30V.
Then you need a better bench PSU or a
dual supply that allows you to gang them
in series (like mine does, 2x30 -> 60V).
None of them seemed to show any
leakage, but my bench PSU will not
display currents below 10mA
That's not good enough either. 10Ma
would be far too much leakage.
I am not sure if that is enough to
show leakage that matters. I also
tested their capacitance values, a few
are well above nominal value, but
within the tolerance shown on the
printset. The worst one is +41% when
the range is +50-10%.
Why do you consider +41% to be "worst"?
Sounds better to me.
I started checking some of the
tantalum capacitors. They all looked
fine, but I don't know what a sensible
ESR value is for these. One of them
(C315) is rated 1uF 35V and has an ESR
of 3.4. Is that high for a tantalum?
One respondent asked for a picture,
the printset is here,
http://manx.classiccmp.org/details.php/1,5422
and the relevant drawing is on page 58.
That was me. Do you have a photo of the
actual board you're working on?
As far as the non-electrolytics, mainly
start by just making sure none of them
are shorted or open.
- J.