Tantalum Capacitor Orientation. - Page 1
Forum section: electronics / repair

author: jerb
author_rank: Contributor
timestamp: March 26, 2020, 12:45:16 pm
content: Working on this camera project and i've run into something i can't quit wrap my head around. Is there any way this tantalum is either improperly oriented or am i just losing my mind? I test probed it and the top with the line is connected to the negative. Bottom without the line should then therefore be positive. Capacitor is not shorted out afaik but i don't understand is it actually possible that this left the factory with a reversed oriented capacitor?

author: wraper
author_rank: Unknown
timestamp: March 26, 2020, 12:50:41 pm
content: Quote from: jerb on March 26, 2020, 12:45:16 pmBy negative do you mean GND? If it's so, it does not mean capacitor is connected improperly since there might be negative voltage (below GND) generated within circuit. You should measure voltage across the capacitor when circuit is powered.

author: jerb
author_rank: Contributor
timestamp: March 26, 2020, 12:53:50 pm
content: I guess i hadn't really though about negative voltages existing within the circuit. but yah sorry meant GND, I'll see if its possible the only problem is it's difficult to attach everything in a way that would allow me to power up the camera with everything attached, and also probe the voltages on the capacitor.

author: wraper
author_rank: Unknown
timestamp: March 26, 2020, 12:57:24 pm
content: Just solder a piece of wire to negative terminal so you can test the voltage when circuit is put together.

author: jerb
author_rank: Contributor
timestamp: March 26, 2020, 09:04:32 pm
content: Voltage on the negative side of the capacitor shows around -4 to -4.5v. So i'm assuming then it is correctly orientated. Guess i'll start digging elsewhere for answers. My problem is that half of the image sensor is not working. So basically i have a split right down the middle where one side works and the other side is completely black. I'm either assuming the main image processing chip has failed or somehow im not getting power to one half of the sensor. I've been digging around on the Main pcb but i've also been trying to see if i can find anything with the sensor pcb. That jumper wire in the photo is factory. Wonderful engineering work for what was originally a 22k $ camera.

author: jerb
author_rank: Contributor
timestamp: March 27, 2020, 01:10:14 am
content: So that is one of the two issues but the other is the top lcd doesn't work. I cleaned the contacts because i found that it wasn't making contact on the 2 power lines but then i realized why, the one pin read around 3.3v while the other was around 13v. I'm pretty sure an oled display isn't suppose to take that much voltage. This Repair is for a Leica S2. Kind of frustrating but i figure it would be good to have some pictures online since there are absolutely none.

author: Miti
author_rank: Super Contributor
timestamp: March 27, 2020, 03:13:42 am
content: Quote from: jerb on March 27, 2020, 01:10:14 amOh, yes it is supposed to take that much voltage.And if that cap was reversed, on a board that was turned on, it would be very obvious.

author: jerb
author_rank: Contributor
timestamp: March 29, 2020, 07:25:30 am
content: An Oled display is okay to take 13v? From everywhere i read online, most OLEDS only take up to 5.5v. Just wanted to clarify what i've read.

author: Till Matte
author_rank: Contributor
timestamp: April 06, 2020, 09:02:27 am
content: The OLED screen can take 13v, the 5.5v is only mean the logic voltage to oled module, but to oled screen, it need higher voltage such as more than 10V to light up the oled screen. most ofoled display modulewould need the DC-DC circuit internal to bump up the input voltage from 5V to 13V or more.

author: SilverSolder
author_rank: Super Contributor
timestamp: April 06, 2020, 11:37:33 am
content: It isn't unlikely that the fault lies with a connector somewhere - cameras are sometimes dropped / jarred which can shake things loose.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: April 12, 2020, 10:10:47 pm
content: One thing I do not see mentioned here is Tantalum SMD Polarity markings. Normally capacitors are marked for negative polarity with a dark band. Not so for Tantalum SMD caps! The dark band is Positive!https://www.vishay.com/docs/40002/293d.pdfEven NASA has issues with it!https://nepp.nasa.gov/npsl/Capacitors/39003/NEPAG-LLB-2001-002.pdfhttps://www.nasa.gov/sites/default/files/atoms/files/nesc_tb_15-01_preventing_incorrect_installation_of_polarized_capacitors.pdf