How to test "Q6" component - Page 1
Forum section: electronics / beginners

author: electrofix
author_rank: Contributor
timestamp: July 18, 2023, 12:55:44 pm
content: Currently I have a capacitor meter that is only working from microusb port. It does not turn on using battery port. Does anyone know how to test "Q6" below?

author: Grandchuck
author_rank: Super Contributor
timestamp: July 18, 2023, 07:45:08 pm
content: No one seems to be around to take a stab. So, here goes:Is the battery voltage at point 1? At point 2?Q4 seems to be the driver for Q6, so it could be the problem.Apply a few volts through a 3.3 kohm resistor to point 3 and see if point 2 goes high.

author: electrofix
author_rank: Contributor
timestamp: July 18, 2023, 08:30:12 pm
content: GrandchuckHere are the voltage reading results:Point 1= 2.94VPoint 2= 0.4VPoint 3= 2.94VResistor test to follow...

author: Grandchuck
author_rank: Super Contributor
timestamp: July 18, 2023, 08:47:33 pm
content: Point 3 is already high. Try pulling it low with a resistor.

author: golden_labels
author_rank: Super Contributor
timestamp: July 19, 2023, 03:04:09 am
content: Knowing, what Q6 is, would make testing much easier and reliable. The component has markings. Please provide them.

author: 807
author_rank: Frequent Contributor
timestamp: July 19, 2023, 10:58:49 am
content: Giving us the model number of the meter might help too.

author: electrofix
author_rank: Contributor
timestamp: September 08, 2023, 02:55:42 am
content: Quote from: 807 on July 19, 2023, 10:58:49 amIt is an Excelvan M6013

author: electrofix
author_rank: Contributor
timestamp: September 08, 2023, 03:11:34 am
content: More close up pictures with microscope:

author: u666sa
author_rank: Frequent Contributor
timestamp: September 08, 2023, 03:57:18 am
content: Obviously you have a bad battery.To test Q6 you gotta find out what it is, transistor or mosfet, it's done with markings on it. You goggle the markings, and get an idea of what it is. Then you pull out your multimeter and test off circuit.You can also connect power supply to battery terminals, see if it is the battery or not.

author: DavidAlfa
author_rank: Super Contributor
timestamp: September 08, 2023, 06:18:18 am
content: Leave it connected for few hours.Normally devices consider 3.7V 0% battery, so at 3V they won't won't turn, ever.Measure the battery voltage from time to time, this simply seems a case of deep discharge, if the battery voltage doesn't increase even bit you might have a charger circuit problem, but also sometimes the system becomes unable to charge once it reaches such low levels, so you might also try to charge it manually by setting a PSU to 4.2V, limiting the current to 1/3 of the battery capacity, so if the battery is 1Ah charge it at 300mA.Apparently it's unsafe to provide high currents to deeply discharged batteries, so I always did like this, never had a problem.

author: gamalot
author_rank: Super Contributor
timestamp: September 08, 2023, 08:42:00 am
content: Q6 is a P-channel MOSFET VB2290.https://datasheet.lcsc.com/lcsc/2211091100_VBsemi-Elec-VB2290_C416211.pdf

author: electrofix
author_rank: Contributor
timestamp: September 08, 2023, 12:53:37 pm
content: Quote from: DavidAlfa on September 08, 2023, 06:18:18 amHi David, thank you for your reply. I probably did not explain the issue correctly. This meter does Not charge the batteries. It uses normal batteries(Two AA Batteries, See attached picture). The unit used to work fine from just regular batteries. (It does not use rechargeable batteries). All of a sudden it stopped working from batteries and only works from the usb connector. Even if I put in two brand new AA batteries, it does not work. As soon as I plug it into USB power, it works, if I remove the USB power, it turns off. What I am trying to do is to see how I can fix it so it works off of battery power again. Sorry if I caused confusion on what the actual problem with the unit is.

author: DavidAlfa
author_rank: Super Contributor
timestamp: September 08, 2023, 05:28:00 pm
content: Take the DMM in diode mode and measure this, without any power source connected!

author: electrofix
author_rank: Contributor
timestamp: September 11, 2023, 01:19:45 pm
content: Hi David, thank you! I got OL for the test you mentioned. However if I reverse it as seen in the picture, I get .44.

author: DavidAlfa
author_rank: Super Contributor
timestamp: September 11, 2023, 01:24:08 pm
content: Expected if it's a pfet.Quote from: electrofix on July 18, 2023, 08:30:12 pmAnd with those readings, it seems it's ok. Now show the rest of the pcb!

author: electrofix
author_rank: Contributor
timestamp: September 12, 2023, 12:49:44 am
content: Thank You David attaching new files.

author: electrofix
author_rank: Contributor
timestamp: September 12, 2023, 12:50:40 am
content: More pictures...