DC-DC 12V>5V-3.3V power board problem (DDPAI X1 mini car DVR) - Page 1
Forum section: electronics / repair

author: Koray
author_rank: Regular Contributor
timestamp: October 11, 2017, 06:03:01 am
content: Hi all,Here I have a little power board from a high-end car DVR (ddpai mini X1) that has failed. There is a whining noise coming from the inductor. U1, C4, and L1 gets really hot. At unloaded state I measured 1.2-3V at 5V output and 0V at 3.3V output; Vin on U1 measures around 9.8V. Photos of the board are attached.U1 is ACT4523A and U3 is labelled DM61X. I assume U3 is 3.3V voltage regulator. The micro USB input socket mates with a proprietary cable that connects to 12V car lighter plug. At the back of the board there is a ZIF connector that provides 5V and 3.3V to the mainboard via a ribbon cable.I suspect ACT4523A is shot. I found a very similar ACT4523 at aliexpress costing $3 for 5 pack. The only difference between two is former being 3.5A, latter 3A. The DVR is labelled to take 12V 1A, so would 3A version be an OK substitute? In the worst case scenario can I substitute an ebay sourced DC-DC buck converter (a tiny one attached to the message) for this one?Thanks in advance.KorayPDF file link for the ACT4523A datasheet:http://www.active-semi.com/sheets/ACT4523A_Datasheet.pdf

author: Armadillo
author_rank: Super Contributor
timestamp: October 11, 2017, 01:53:29 pm
content: Do not further turn the power board on until you replace C4, if I were you.IMO, the ebay converter cannot match the power board because the power board you have, has many protection on board like reverse polarity and regulation etc...I doubt the ebay small board can deliver what it says, could be peak pulse current stated instead of continuous dc usage current.

author: Koray
author_rank: Regular Contributor
timestamp: October 11, 2017, 07:43:24 pm
content: Thanks! So replacing the U1 and C4 would be the first step, right? From the sample circuit diagram above I assume it is 47uF am I correct?K.

author: Armadillo
author_rank: Super Contributor
timestamp: October 11, 2017, 07:57:32 pm
content: Quote from: Koray on October 11, 2017, 07:43:24 pmJust replace C4. You need to measure the size of the cap, I cannot see from the picture. Probably its a 1812 size? Check it. 47uF, X5R type.

author: Koray
author_rank: Regular Contributor
timestamp: October 12, 2017, 05:32:24 am
content: Thanks again! I checked its dimensions: 3.2mm x 1.6mm with 1.7mm height. So this makes it 1206, right? Then what capacitance should I look for?Thanks for your help.Koray

author: Armadillo
author_rank: Super Contributor
timestamp: October 12, 2017, 05:39:13 am
content: Quote from: Koray on October 12, 2017, 05:32:24 amSee attached. I hope you know how to do smd soldering. 1206 is not that difficult. Watch some youtube for insights.Do remember to protect other components.

author: Armadillo
author_rank: Super Contributor
timestamp: October 12, 2017, 06:57:29 am
content: Unless you have electronic shops nearby, buying a single component online would not be economical. If you have some scraps boards lying around, just extract the similar size cap and do the replacement. No need to be exact sciences. Anything from 10uf to 100uf at 10/16volts will work. .... Or solder a small axial electrolytic cap in...

author: Koray
author_rank: Regular Contributor
timestamp: October 12, 2017, 06:59:25 pm
content: Great information. I can do smd soldering. This thing is less than a centimeter away from the top edge of the windshield, so during summer it gets very hot. It failed in less than a year. So I guess an electrolytic cap won't do. The are some AliExpress listings with huge variety of smd caps for a few bucks. I will try them.Thanks again. I will update once I receive parts.K.

author: Koray
author_rank: Regular Contributor
timestamp: November 08, 2017, 08:47:30 am
content: Hi again,After a long wait I received the parts (C4 and U1), and first replaced the C4, then U1. No luck. Then I noticed the SD2 (labelled AE) was getting smoking hot when powered.So I removed that diode and now all is well, perfect 5V output (but no 3.3V). When I measure the diode's resistance, it is shorted both ways. I assume it is faulty.Can anybody help me to identify that diode? I think it is under 5V load and dimensions are about 2.5mm x 1.5mm.Thanks for help!KorayEDIT: I think the diode is a 5V TVS one, I found this code: SMAJ5.0A, though dimensions are not a match.

author: Armadillo
author_rank: Super Contributor
timestamp: November 08, 2017, 10:07:28 am
content: Quote from: Koray on November 08, 2017, 08:47:30 amOf the U1, C4, and L1 which you said were very hot, you didn't say AE was hot.... hahahaha LOL.... OK it's a gottcha me....I suppose this time, you should turn it on without AE, negative to ground, measure voltage at Pin 1,2,3,4,5 of the DM61X with respect to 3.3 volts ground.Then with it off, wait discharge all caps then measure the ohms of the DM61X Pin 1,2,3,4,5 with respect to 3.3 volts ground.At least, we identify if there are any more shorts to ground and make sense of DM61X.The AE is labelled on the circuit board as SD2..... Schottky Diode??

author: Koray
author_rank: Regular Contributor
timestamp: November 08, 2017, 12:27:48 pm
content: Thanks for your reply Armadillo!You are right, I always tested it in my car, so at its awkward location I missed the red-hot diode. Sorry.I now powered it again, and for DM61X PIN1 is 5V, PIN2 is shorted to ground. There is no voltage on other pins. When power is off PIN3 is 2.1kOhm, PIN2 is shorted to ground, and the rest are open. The diode sits between PIN1 and PIN2, 5V and ground respectively.Is DM61X a voltage regulator? How can I search for it on Aliexpress? If DM61X is shot, can I substitute an RT8059 instead? I have some and they are labelled BQ with the same package.Thanks for help!Koray

author: Armadillo
author_rank: Super Contributor
timestamp: November 08, 2017, 02:01:14 pm
content: Quote from: Koray on November 08, 2017, 12:27:48 pmI don't think is a RT8059. Because the pinout and connection is not the same as the circuit board compared to the datasheet. At least there need to be a inductor at Pin 3 which is not the case.I more think that it is a TC1014. The pinout and connection seems to be quite the same as the pcb. Can you trace to see if it is close enough. In the pcb, can see the pin 3 shutdown or enable pin is connected to a voltage divider by 2 resistors and trace to the connector pin. I suppose this needs to be enable to make the 3.3v available. Before you replace it, it is worth to temporarily try to say bridge the Pin1  to pin 3 [according to page 6 of datasheet] to serve as enable and measure if 3.3v is enabled [Pin 5 should measure 3.3v to ground].BTW, does your DVR need the 3.3v?

author: Koray
author_rank: Regular Contributor
timestamp: November 08, 2017, 02:27:27 pm
content: Hi again, no I don't really know if the DVR need 3.3V, I am just speculating. Maybe that chip does something else? Maybe I should test the board on the camera to see if it works now.I will try your suggestions. Any ideas what that diode is for?Kind regardsK.

author: Armadillo
author_rank: Super Contributor
timestamp: November 08, 2017, 03:57:04 pm
content: Quote from: Koray on November 08, 2017, 02:27:27 pmHi, pure speculation that the diode can either be;a) a "Zener" to limit the input voltage for LDO regulator DM61X,ORb) a "diode" to serve as reverse protection against 1st stage buck converter diode failure.But since the PCB labelled as SD, so I speculate that it is case "B", more likely.Pure speculation only.

author: Koray
author_rank: Regular Contributor
timestamp: November 08, 2017, 04:27:15 pm
content: I came across AP-131-27W with the correct packaging and marking code, and matching pinout. So it may be 2.7V instead?Any chances I can find this chip (or a substitute) somewhere easy (if it is faulty, I have yet to test your enable suggestion)?Thanks!K.Edit: Marking code doesn't match, sorry, fourth digit has to be a letter in the case of AP-131Edit 2: I am including the camera chipset datasheet, too. I guess it requires 3.3V, right?

author: Armadillo
author_rank: Super Contributor
timestamp: November 08, 2017, 09:06:50 pm
content: Your camera should have its own intrinsic power management.Any wiring diagram of your DVR, that would help.Otherwise try the enable or find the connector pinout.

author: Armadillo
author_rank: Super Contributor
timestamp: November 08, 2017, 09:31:31 pm
content: The DDPAI X1 mini car DVR uses very standard USB car power adapter 5V @ 2.1A, according to the user manual.Is your adapter the original?

author: Koray
author_rank: Regular Contributor
timestamp: November 09, 2017, 09:17:22 am
content: Hi again Armadillo!DDPAI mini X1 has direct 12V connection on it, so it does not need an external power adapter. This little power module I show is on the unit itself. It has a micro-usb input, but the micro usb cable brings 12V from car battery. Weird stuff. They clearly mention that you should not use that micro usb cable to charge your phone etc. I think they stopped selling this model because of these issues.Anyway, good news, I tried your suggestion, connected PIN 1 to PIN 3 to enable the chip, and voila 3.3V output!Now I checked the circuit board, and the enable signal is coming directly from the PIN 2 of micro usb 12V connector! But when I checked the original cable in the car, there is 0V on that pin. So it is not connected to the battery. Then it dawned on me, maybe it is a reserved pin for a special cable, and the 3.3V circuit could be just for that reserve function. Maybe there is a special cable that tells the camera that the ignition is off, and camera starts the special parking mode function, I don't know.BUT! I put the camera together and you were right, it just works now!No problems with recording or connecting.Now the question is, what diode should I put in the SD2 position? Looking at the sample circuit diagram above, I cannot see a need for it.I am attaching an updated circuit diagram with values. It may be useful for someone else in the future.Thanks for your help all the way, Armadillo.K.

author: Armadillo
author_rank: Super Contributor
timestamp: November 09, 2017, 10:08:11 am
content: Congratulation, Great news...See if MBR130 fits the size..... or make do with 1N4148 or just leave it....

author: Koray
author_rank: Regular Contributor
timestamp: November 09, 2017, 06:09:36 pm
content: Thanks again, Armadillo. Without your help I would give up.Koray