22 Jul
2015
22 Jul
'15
8:11 a.m.
On Wed, 22 Jul 2015, tony duell wrote:
When I pull capacitors from a board, I put them into numbered trays for
testing. Each new part also gets another quick test before installation
and the results of both get entered into a spreadsheet (along with date
codes, part numbers, and any other data I have on hand). I did this
initially for mission critical boards so I could provide the data to
customers who needed that level of detail, but I later started doing this
for all repairs because I found it wasn't all that difficult to do once I
already had a system in place. When I'm testing old parts, I also note
things like leaky seals, corrosion around the terminals, etc. Because of
the historical data I've collected, I can also tell from my notes that
there are definitely certain brand/series (both vintage and modern) which
have common issues.
Given that a
typical aluminum electrolytic capacitor costs anywhere
from $0.12-$0.15 (4mm or 5mm diameter radials) to about $1.00 (12mm or
16mm diameter radial), it also doesn't make much sense to desolder a 20
year old part, spend at a minimum 5 or more minutes testing it, and
then solder it back in. It it much more economical to pull the old part
and install a new one and be done with it. (You also don't have to
worry if the desoldering and resoldering process might have damaged the
original parts end-seals.) That said, I personally pre-test new parts,
in bulk, before I
I don't remove parts unless they have something to do with the problem I
am solving. If the power rails are the right voltage with sufficiently
low ripple then I look elsewhere for probkems.
put them into my stock, so I know ahead of time
that I'm installing
known-good parts.
You claim that electrolytics deteriorate with time whether used or not.
How do you know the ones you install haven't deteriorated since you
tested them?