6
times depending on the
ESR
of the cap. The
CapAnalyzer
88A
has been designed to chirp
once
if the ESR is less than one ohm;
Two
chirps from one to two ohms,
three
chirps from
two to three ohms;
four
chirps from four to eight ohms; and
five
chirps from 8 to 20 ohms.
The handy three-color chart on the front panel shows typical ESR readings, so if a 2.2 uF
cap chirps three times and shows 3.00 ohms ESR, the chart shows that this is in the green,
good. If you ever used the original CapAnalyzer 88 or 88A, you might have discovered the
unusual case where the
CapAnalyzer
chirped five times and there was no reading at all; this
usually indicated a good bi-polar capacitor (found in some TVs) which show
less
than zero.
CapAnalyzer 88A
Series
II
units will correctly show the actual ESR.
As a rule, some caps can show in the yellow area, and may still work adequately. It is up to
the technician to make the decision on whether to replace these questionable caps, or not.
However, any caps that show ESR in the red areas are out of spec and
must
be replaced. For
capacitors that check as shorted, see the SHORTED CAPACITORS section.
Low-voltage surface mounted caps are usually very poor in quality and even new ones may
show in the yellow areas. Most quality-oriented service companies replace surface mount
caps with conventional caps, as long as they will fit, assuming the technician has the skill to
cut the leads very short and solder them in without melting everything in sight.
Note that if an electrolytic capacitor is in such bad condition to be over 20 ohms ESR, the
CapAnalyzer
will treat it as an open circuit and
will not even try to test it
. The
OVER
indicator will continue to flash. Replace these caps, as they are bad, no matter what their
capacity is. If you wish to double-check the test probe, short the probe contacts together
while turning on the unit to activate the
InstaESR
mode, and the
CapAnalyzer
will do a
self-test; the top LED should be lit, steady. Wiggle the test cable at each end to check for
frayed strands. You can also check calibration at any time with a 10 ohm resistor: set the
DCR OHMS alert to zero and measure across the resistor; the 10 ohm ESR led should
illuminate. And always make sure the tweezer tips are kept clean or accuracy will suffer.
In some cases, you may find capacitors that are physically leaking, yet they check as perfect.
Although the cap is leaking, it has not leaked enough electrolyte to render it defective and
will still operate perfectly in the circuit...for a while. If you wish to avoid callbacks, replace
them anyway.
NOTE: Although the
CapAnalyzer
automatically discharges capacitors before testing,
remember that there are limits. If the capacitor is large enough, and there is enough voltage
stored to blow the ends off of the test probes, you will have to replace the probes as well as
the discharge diodes and resistors in the discharging circuit of the instrument. Therefore,
use common sense when measuring large electrolytics that may have a serious charge
