MICROHMMETER CHAUVIN ARNOUX CA6240 FAULTY BATTERY INDICATOR - Page 1
Forum section: electronics / repair

author: HUGOMAN
author_rank: Regular Contributor
timestamp: January 12, 2022, 08:49:02 am
content: HI TO ALLI have the CA6240 with error status of battery indication not shown full ? i did check the voltage of charger is approximately 10Vdc; i should check somthing in the same area!Regards

author: HighVoltage
author_rank: Super Contributor
timestamp: January 12, 2022, 10:13:35 am
content: I would start with the internal battery that might be old.

author: HUGOMAN
author_rank: Regular Contributor
timestamp: January 12, 2022, 10:18:26 am
content: In fact I just replaced the battery sûre there something in the board who reads battery status I guess like a resistor opened or what I don’t have any schematic

author: HighVoltage
author_rank: Super Contributor
timestamp: January 12, 2022, 10:28:09 am
content: Show some pictures from the inside.Maybe we can see something and help, I am not sure.

author: HUGOMAN
author_rank: Regular Contributor
timestamp: January 12, 2022, 10:39:59 am
content: Ok that’s Great

author: HUGOMAN
author_rank: Regular Contributor
timestamp: January 12, 2022, 07:56:14 pm
content: THIS IS THE BOARD where is the battery is connected, the failure after testing it it reads a 1,5ohm who is not real then after some seconds it reads the correct value 5,0 ohm also happen with 20ohms after a few moments it reads the correct value.also the battery indicator is not full even after a FULL charge finished message!Regards

author: HUGOMAN
author_rank: Regular Contributor
timestamp: January 12, 2022, 07:58:17 pm
content: sorry the photos could not be uploaded!

author: HUGOMAN
author_rank: Regular Contributor
timestamp: January 12, 2022, 08:01:35 pm
content: the front side

author: shakalnokturn
author_rank: Super Contributor
timestamp: January 13, 2022, 02:09:48 am
content: The top side of PCB doesn't look clean. Has it experienced battery leakage at one point? Electrolyte residue or corrosion in the wrong place could throw the battery level sensing off.

author: HUGOMAN
author_rank: Regular Contributor
timestamp: January 13, 2022, 08:11:16 am
content: Hi shakalnokturnthe male connector of the board was broken from the top so i was obliged to remove it and put another good board connector, and beside this is only flux because i check those terminals at the first time i believed that was a short circuit but i found only the 2 white resistors are in parallel, visually i don't notice anything wrong !

author: HighVoltage
author_rank: Super Contributor
timestamp: January 13, 2022, 09:29:23 am
content: What type battery is installed and where is it hooked up?

author: HUGOMAN
author_rank: Regular Contributor
timestamp: January 13, 2022, 11:42:10 am
content: Lithium battery connected to the board terminals battery voltage.I made some testing this morning.1/ the microhmmeter displays 100 FULL means that the system reads the battery but the battery indicator stays empty on the display?2/ the microhmmeter reads the resistance instantly but when I measure a big transformer it reads a wrong value like 1,5ohm then after some seconds it reads the correct value 5,6 ohm, so I conclude that it couldn’t read the big coils transformer at the first time?Welcome for any investigation thanks.

author: Kleinstein
author_rank: Super Contributor
timestamp: January 13, 2022, 12:35:48 pm
content: It is rather difficult to measure the resistance of a tranformer, as the inductance is significant. Not all meters like such an inductive load. With this meter one may have to choose the right mode - there seem be several options to set (e.g. lower test current).The problem with the transformer may not be battery related.For the transformer it can help to shorten a winding not used in the test. This reduces the inductance by a lot.

author: HUGOMAN
author_rank: Regular Contributor
timestamp: January 13, 2022, 12:58:01 pm
content: Thanks Kleinstein for your answerNo the owner is used to test this transformers; he told me even the battery at low level it reads the coils at the first time without this delay. So it means that not comes from battery. For battery I replaced the dead one with lithium that I made it by myself.The problem is no schematics no second instrument to make some comparisons.

author: Kleinstein
author_rank: Super Contributor
timestamp: January 13, 2022, 04:38:23 pm
content: So are there 2 problem: the battery dead and changed and the measurement not working ?The battery symbol often only shows up when there is a problem with a low battery - this at least the way most handheld DMMs use it.For checking the ohme mode, a first thing to check are the test currents - they are given on the front, so some point to check.A next point would than to test some resistors near the upper end of the ranges. So test of the funktionality if things are OK at least for normal resistors.

author: HUGOMAN
author_rank: Regular Contributor
timestamp: January 13, 2022, 07:00:08 pm
content: Yes Mr Kleinsteinok for the display battery indicator we don't mind about.But for measurement the test was made for resistors different values on 40 ohm range because the most used by this tester, so all values are read correctly but when i measure big transformer is different can't read the correct value at first time it gives a primary value lke 1,5 ohm then after a few moments it displays the correct one who is 5,6ohm.it's abnormal it should read value at the first time!!! ? i don't have any support to know the issue and fix it

author: HighVoltage
author_rank: Super Contributor
timestamp: January 14, 2022, 09:31:58 am
content: Instead of using the battery, I would hook up a good quality DC power supply.This way you can see when the battery indicator is turning on and offAlso you can test the tester this way and watch the current consumption.At least this will give you an idea if there is a difference between battery usage and power supply usage.Just make sure you do not go higher in voltage as the nominal battery voltage.

author: HUGOMAN
author_rank: Regular Contributor
timestamp: January 14, 2022, 12:47:00 pm
content: OK Great Mr Highvoltage i will perform this and i come back to you.