|
Technical support
Click on the symptom:
Calibration Instructions
Intermittent testing, ESR shows too high or not at all
5 Beeps and no ESR reading at all
Lost my Owner's Manual
After a Nasty Discharge, strange behavior
Batteries only last a few hours
Update my EDS-88 to EDS-88A
Test lead tips broken off
Button gets pushed on in toolcase
Low Battery indicator doesn't work
No detection of Shorted caps
Readings keep changing each time the same cap is checked
Sometimes the 20 ohm led comes on dim with another led
Power button seems to have a delay powering up
Calibration Instructions:
Set the ZERO and FULL trimmers fully to the left (counter-clockwise). Set the
SET ALERT slider to zero (all the way down). Have a 20 ohm resistor handy.
CALIBRATING ORIGINAL 1997 EDS-88 ONLY:
1: Turn on the unit; it will chirp three times and immediately go into the ESR
alignment mode and wait; one of the led bar segments will be on. Hold the
tweezer probes across the 20 ohm resistor and adjust the FULL trimmer so the
the bottom 20.0 ohm just comes on.
2: Quickly, before the CapAnalyzer resets, short the probe tips together and
adjust the ZERO trimmer so that the 0.10 led bar just goes out, and only the top
OHMS bar led is on. If you did not move the probe quickly enough, simply touch
the probe across the resistor again briefly to start the test, and wait until
the CapAnalyzer is in the ESR test (after the green OK led comes on) before
quickly shorting out the probe tips again.
3: Touch across the 20 ohm resistor and make sure the 20.0 ohm ESR bar comes on.
CALIBRATING EDS-88A and SERIES II ONLY:
1: Turn on the unit; it will chirp and go into the QuickESR test mode and
wait; all leds will be off. Hold the tweezer probes across the 20 ohm resistor
and adjust the FULL trimmer so that the 20.0 led bar just
comes on.
2: Short the probe tips together and adjust the ZERO trimmer so that the top led
bar just dims slightly.
3: Touch across the 20 ohm resistor and make sure the 20.0 ohm ESR bar comes on.
You can double-check the ESR scale by measuring various resistors between zero and 20 ohms and make sure the ESR readings agree with the resistors.
Lost your owner's manual? press here to download a text copy or here to download an MSword copy.
If your unit seems to be intermittent in checking caps, in all cases this has been poor solder connections of the wires of the Pomona tweezer probe. On the original 1997 EDS-88 with straight tweezer handles, the problem is usually at the probe tips. Remove a quarter of an inch of insulation of the wire where soldered to the brass tip, then run a bead of solder from the tip to the wire. On EDS-88A units with curved probe tip ends, the problem has been oxidized crimps where the coaxial cable connects to the red and black wires in the apex of the tweezer. The probe handles must be snapped apart, easily done with the help of a flat-blade screwdriver. Solder the brass crimps and snap the probe handles together using a small amount of super glue. This problem no longer exists with probes made after 2002 as we now make them properly in-house. Normal wear and tear causes the coax bending to cause breakage of the cable where it enters the tweezer; snap the tweezer apart, shorten the coax an inch, resolder, reassemble and superglue the tweezer.
Some users have reported that the 1998 and 1999 CapAnalyzer 88A does not check bi-polar electros (like the ones in Thomson TV chassis), by beeping 5 times and showing no ESR reading. Actually, the reading is less than zero! One of our users with a Sencore LC101 reported that the Sencore actually showed minus ohms. Strange cap (play Twilight Zone music here). Just remember that five beeps and no reading of ESR leds means a good BIPOLAR cap; however, if this happens on a regular electrolytic, you might check the section above. By the way, this is only noticable on CapAnalyzer 88A units made before August 2000; since the original CapAnalyzer 88 units had an "ESR" led above the lowest reading that always remained lit, it fooled most technicians in reading it as a lower value. CapAnalyzer 88A series II (all units made after July 2000) have a different LED driver chip that correctly lights up the top LED.
BANG!
Although your CapAnalyzer will discharge a cap before testing it, sometimes a cap is just a little to big and charged up a little too high for the CapAnalyzer to handle. The auto-discharge is mainly to make readings more accurate and is not designed to discharge large, primary HV electrolytics right after the bridge. Short these with a screwdriver. If you ignore this warning, after a large discharge, you will know that you have damaged your unit if it keeps going into test mode as soon as you turn it on, or seems to try to test a cap and shows DCR LOW on every cap. The fix is usually easy and cheap; see the drawing. Simply replace the three resistors shown; they are designed to protect all of the active electronics. Use 1 watt metal oxide for the 4.7 ohm and 3 watt wire-wound for the 0.47 or 0.6 ohm discharge resistor. If your unit keeps going into test mode as soon as you turn it on, check the two discharge diodes (out of circuit) by the 3W resistor. If it seems normal at first, yet shows DCR LOW on every cap, replace the LM324 chip. An important note here is that stupidity can still destroy a CapAnalyzer. Forget to remove power from the TV or VCR that you want to check the caps in, and your CapAnalyzer will happily kill both the unit-under-test as well as itself. Besides replacing the three resistors, you'll also have two 220 ohm resistors next to the large 1000uF/10VDC cap that will be burnt up, and you'll also need to replace the NE555, TLC2272, and the LM324 chips. DO NOT SUBSTITUTE USING NTE, ECG OR ANY OTHER SUBS! Beware that the board is double-sided and through-plated and you need to use desoldering equipment designed to work with this type of board. Soldering braid won't work. If you do not have the proper equipment, you may send your unit and we will repair and calibrate it for you. See the "Repairs" webpage for details. And next time, let's be more careful out there!
AC ADAPTER OPTION AVAILIABLE The original EDS-88 and EDS-88A units are rough on batteries. Most techs report between 3 weeks and two months, as long as the unit is turned on just long enough to check some caps, then turned off. Some of the bigger shops would prefer to keep it on all the time. Don't try to make your own adapter; any voltage higher than 6.25V destroys the mpu. We can send you an upgrade kit that includes the DC jack and specially modified adapter; see the Order Form page. We can modify your CapAnalyzer for you as well. Or order a brand-new CapAnalyzer 88A Series II with the optional adapter option already installed and give your old CapAnalyzer to the field tech. (The series II units get double the battery life because of upgraded LED driver chips). To order a new unit, or parts for your old unit, press HERE.
INSTA-ESR QUICK TEST MODE AVAILIABLE FOR ORIGINAL EDS-88 (1997)
A feature many users of the original CapAnalyzer had asked for is the quick ESR test mode that bypasses the long discharge and DCR test when you are sure that no shorts exists, such as checking all of the surface mount caps in a camcorder or video module as quickly as possible. The EDS-88A made after 1998 has this feature.
Available is a replacement mpu chip for the original 1997 EDS-88. With this new mpu, turning on the CapAnalyzer with the test probe tips touching tells the C88 to enter the new program...now as soon as you check a cap, the ESR test is done immediately, in a split second. To use the original full discharge and DCR test sequence, simply turn on the C88 normally. This mod is available if you send your unit back to us; see the "Repairs" webpage. We will also update your unit to current specs, so if you have the original C88 without the three-minute warning timer, you will get this also. There are no updates for the analog measuring circuitry, because after all, you can't improve upon perfection.
DCR MODIFICATION
As you know, the original 1997 CapAnalyzer 88 automatically checks capacitors for low DCR (DC resistance) before checking ESR. The original 1997 EDS-88 has a range adjustable from zero to 50 ohms. However, if you are troubleshooting boards that use surface mount TANTALUM capacitors (not electrolytic), we have discovered that in rare cases, these capacitors can become leaky with DC resistances as high as 500 ohms. Therefore, a new range of up to 500 ohms DCR is the solution.
The EDS-88A has this new range; on the original 1997 EDS-88, there is a simple and easy fix: Open your unit and locate the 27 ohm resistor just above the "ZERO" trimpot, and replace it with a 270 ohm resistor.
Now, mentally add a zero to the 0 to 50 ohm DCR ALERT adjustment. However, BE AWARE that if you measure normal electrolytics, you must set the slider to the "5" (now 50 ohms). Use the higher range for small tantalums or electrolytics under 47 uFd. You will get a false "LOW DCR" if you try to measure a large electrolytic with the slider set too high, because the time to charge and test the cap is longer than the DCR test check.
TEST LEADS The tweezers are no longer made by Pomona. Most tweezers are easily repaired, and if the tips are broken off, we mail you two pieces. Note, however, it requires careful work since the originals are melted in place, and we will only mail you the set ONCE. As an alternative, you can
use the Cal-Test CT2987 tweezer; it is very close to the Pomona.
see: Cal-Test Since the Cal-Test uses a shorter cable and has a BNC connector, you will have to cut off the connector and after soldering into your Capanalyzer you will have to realign the HI & ZERO trimmers. If you find a replacement set that you wish to use instead, you will have to realign the HI & ZERO trimmers. Instructions are at eds88cal.txt. You must use RG-174 coax for the test lead wire, or else readings on small value caps will be inaccurate.
Singing the "RED BUTTON BLUES"
A couple of complaints from the outside guys fixing the big screens about the power button being accidentally pushed on in transit. The quick fix is to simply pull the red button off of the switch--you won't break anything, and you can push it back at any time. A somewhat in-elegant solution, (sorry) but very functional, you can easily push the power on or off with your small finger.
NO LOW BATTERY INDICATOR and NO DETECTION OF SHORTED CAPS
If your older C88 seems to work poorly with low batteries and the "low battery" led does not seem to work properly, you may have one of a small batch of 20 CapAnalyzer 88 units made on 4/18/98 that had out-of-spec MPU chips. These units work fine with fresh batteries. If the unit fails to warn you on a shorted capacitor when the batteries are weak, return your unit directly to EDS for a replacement mpu chip and current updates.
If you seem to keep getting different readings when testing the same capacitor, tap the CapAnalyzer gently on the workbench while the ESR of a good cap is being displayed. If the ESR reading changes (flickering is ok), you have a bad relay. This is from a bad batch of "NAIS" relays on C88s made the second half of 1998. You can send your unit back for a warranty replacement of the relay, or if you have the proper desoldering equipment to work on double-sided pc boards, we can send you a replacement higher-quality OMRON relay.
If the bottom 20 ohm led sometimes comes on dim with another, brighter led above, this is a normal circuit glitch with all C88A units made before August 2000 (caused by our interfacing the National LM3914 led driver ICs into the CapAnalyzers mpu for the improved multi-tone beeper). The brighter led above is the correct reading. Again, the series II units have a new driver chipset that eliminates this glitch.
If you notice that your new C88A seems to delay powerup, Series II C88As use a pair of MCUs that check calibrations and communicate with each other for about a second before flashing the LEDs and beeping OK. This is normal, so stop playing with the red button!
|