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Old 09-05-2015, 11:49 PM   #21
fzabkar
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Default Re: Help identifying a component on a wireless router.

See http://www.rom.by/files/Richtek_Marking_Code.PDF

RT9809-30PV, Micro-Power Voltage Detector, 3.0V, marking DF-:
http://www.cheertech.com.tw/RichTek%...DS9809-04P.pdf

Pinout from left to right - Ground, VDD, /Reset
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Old 09-06-2015, 12:23 AM   #22
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Default Re: Help identifying a component on a wireless router.

Thank you fzabkar. Are you 100% sure that's the part? If so, do you mind me asking how you was able to identify it? I tried everything! I even went to a site to look up codes on SMD components.
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Old 09-06-2015, 12:29 AM   #23
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Default Re: Help identifying a component on a wireless router.

Quote:
Originally Posted by Spork Schivago View Post
Thank you fzabkar. Are you 100% sure that's the part? If so, do you mind me asking how you was able to identify it? I tried everything! I even went to a site to look up codes on SMD components.
See http://www.rom.by/files/Richtek_Marking_Code.PDF

The "-" in the part marking suggested Richtek.

The top side of the PCB appears to have 3 switchmode supplies. Confirm that there is continuity between the centre pin of U40 and one of the SMPS coils. Also confirm that the left pin is grounded.

If the left pin is grounded, as it appears to be, then the part is highly unlikely to be a transistor. That's because the typical pinout is BCE or GDS, and grounding the B or G would make no sense in this circuit, AFAICT.

Last edited by fzabkar; 09-06-2015 at 12:49 AM..
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Old 09-06-2015, 02:57 PM   #24
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Default Re: Help identifying a component on a wireless router.

Wow, thank you! I'll be sure to do that and report back. I really appreciate everything.
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Old 09-06-2015, 08:25 PM   #25
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Default Re: Help identifying a component on a wireless router.

I believe Fzabkar is correct on U40 as the DF- looks up to be this number on this chart he supplied. I do not know how we found the data sheet to the part but he did.

Fzabkar when you say 3 switch mode power supply. Are you saying that there are 3 individual switching power supplies or are you saying that there is one switching power supply with three different mode levels?
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Old 09-06-2015, 09:06 PM   #26
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Default Re: Help identifying a component on a wireless router.

At the top left corner, near the DC input socket and on/off switch, are two 100uH coils. Adjacent to each coil is a PWM controller IC. Each coil/IC pair constitutes a step-down buck regulator. These are switchmode supplies that convert the DC input (12V ?) to the lower voltage levels required by the logic.

For example, the Samsung SDRAM typically requires 3.3V or 2.5V, as does the 8-pin EEPROM or SPI flash memory (?) to the right of the crystal. The Broadcom controller probably requires a Vcore supply around 1.2V or so. The 3.3V supply would possibly be its Vio voltage. At the bottom left corner is a third buck regulator.

There will most likely be application circuit examples in the respective datasheets for each PWM IC.
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Old 09-06-2015, 10:12 PM   #27
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Default Re: Help identifying a component on a wireless router.

Quote:
Originally Posted by keeney123 View Post
I believe Fzabkar is correct on U40 as the DF- looks up to be this number on this chart he supplied. I do not know how we found the data sheet to the part but he did.

Fzabkar when you say 3 switch mode power supply. Are you saying that there are 3 individual switching power supplies or are you saying that there is one switching power supply with three different mode levels?
I know there's three through-hole transformers on the circuit. Never seen anything like them but they all have the transformer circuit on them. Two of them are the same, one of them is different.
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Old 09-06-2015, 10:16 PM   #28
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Default Re: Help identifying a component on a wireless router.

I didn't get to work on the router today. I had to fix my brothers Gateway 3DS. The MicroSD card slot has issues. We bought it brand new back in May. It didn't work, we contacted them and told them there was an error, something along the lines of "Error reading filesystem". We sent it back and JUST got it back from China a few days ago. Same issue though. I decided to try and repair it myself this time. I unsoldered the shield to see what was under there (the pins where in the middle, so the shield had to come off first) and low and behold, a broken pad! So I took my conductive pen (which kinda sucks) and used it to try and redraw the pad. I skinned a layer off the board to see the trace and made sure the pen went to it. The instructions for the pen (first time using it) says I have to solder it at no higher of a temp than 350F for no more than 5 seconds. I don't have any solder that melts that low I don't think. So this should be interesting. I have to wait 24 hours for the stuff to cure.
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Old 09-06-2015, 10:47 PM   #29
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Default Re: Help identifying a component on a wireless router.

I have to solder it at no higher of a temp than 350F for no more than 5 second.

Leaded solder should melt around that temperature. Otherwise you would have to get low temperature solder I believe has cadmium added to it. To bad the Chinese Company does not believe in QC departments or even testing the board.
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Old 09-06-2015, 10:59 PM   #30
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Default Re: Help identifying a component on a wireless router.

Quote:
Originally Posted by fzabkar View Post
At the top left corner, near the DC input socket and on/off switch, are two 100uH coils. Adjacent to each coil is a PWM controller IC. Each coil/IC pair constitutes a step-down buck regulator. These are switchmode supplies that convert the DC input (12V ?) to the lower voltage levels required by the logic.

For example, the Samsung SDRAM typically requires 3.3V or 2.5V, as does the 8-pin EEPROM or SPI flash memory (?) to the right of the crystal. The Broadcom controller probably requires a Vcore supply around 1.2V or so. The 3.3V supply would possibly be its Vio voltage. At the bottom left corner is a third buck regulator.

There will most likely be application circuit examples in the respective datasheets for each PWM IC.
Thank you for your explanation of pointing out the sections. You must repair these type of units on a regular basis to be able to tell that without ever seeing the IC numbers? I have a good understanding of how the step up and step down buck switching supplies work. I just do not study every detail as I would be lucky to even repair one of these in a year. I know they use coils and zener diode to create these different voltages and the pwm sets up duty cycle. But to study it much further for me would be a waste as I would forget about it in between time.
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Old 09-07-2015, 01:11 PM   #31
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Default Re: Help identifying a component on a wireless router.

Quote:
Originally Posted by keeney123 View Post
I have to solder it at no higher of a temp than 350F for no more than 5 second.

Leaded solder should melt around that temperature. Otherwise you would have to get low temperature solder I believe has cadmium added to it. To bad the Chinese Company does not believe in QC departments or even testing the board.
Can you still buy leaded solder? Regardless of what type of solder I use, I'm going to have to order it. We used to have a Radio Shack up in Painted Post, now we only have one at the mall, but they really lack in that department. Stuff is crazy expensive and almost everything is meant for through-hole components.
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Old 09-07-2015, 01:58 PM   #32
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Default Re: Help identifying a component on a wireless router.

Maybe instead of trying to solder the shield back to where I created the pad with the conductive pen, perhaps I should just solder a jumper wire to ground somewheres. What do you guys think? I know this is a little off topic for the router stuff, but I thought perhaps it'd be better than creating a new topic for just a simple question.
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Old 09-07-2015, 06:29 PM   #33
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Default Re: Help identifying a component on a wireless router.

Quote:
Originally Posted by Spork Schivago View Post
Maybe instead of trying to solder the shield back to where I created the pad with the conductive pen, perhaps I should just solder a jumper wire to ground somewheres. What do you guys think? I know this is a little off topic for the router stuff, but I thought perhaps it'd be better than creating a new topic for just a simple question.
Yes you can still get leaded solder at radio shack or any electronic parts store. I do not know exactly where you are soldering this jumper wire. If you solder it to a trace you could have problem as they do not make the boards like they use to, where one could scrap the traces on either side of the break and solder a bare wire or a lead of a resistor and then cover it up with lacquer finger nail polish. The traces now are really fragile and are easily lifted from the board. I would think the ground plane would be safe to do this to as long as the jumped wire was not very long.
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Old 09-07-2015, 07:27 PM   #34
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Default Re: Help identifying a component on a wireless router.

Can you see where the missing pad is? It's where the grounding shield was attached. On the opposite side, there's still a pad there. I've successfully scraped the trace to expose the PCB so I can try and solder a wire there...but I'm questioning this...

The other side is still a ground. Where does the broken pad lead to? As far as I can tell, it's supposed to connect to the back there (there's two solder pads at the back). They connect to a pin on the opposite side on a big IC, I'm guessing a CPU. So I think all I need to do is solder a wire from the left ground (looking at the pic), to one of the two pads at the back there. Both the back pads are connected.
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File Type: jpg Front Board Pic 1.JPG (668.3 KB, 8 views)
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Old 09-07-2015, 07:35 PM   #35
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Default Re: Help identifying a component on a wireless router.

You know, something like this.

I've checked for continuity between those two points, where the red line begins and where it ends, and there's nothing. My guess is the missing pad connected them. If I'm wrong on this though, it'll probably fry his Gateway.

I could try finding on the other side the pin on the big IC that connects to those back pads and finding a datasheet on the big IC to see if it says ground, but there's a LOT!!! of pins there!

Here's a picture of one torn apart. It's not my brothers, but the IC should be the same. The back pads on the front connect to a pin on the bottom of that pic somewheres. More to the bottom left (looking at it) I want to say.
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Old 09-07-2015, 08:56 PM   #36
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Default Re: Help identifying a component on a wireless router.

The quality of the picture is not good enough for me to see the broken pad. I guess I would establish the power pins on the chips and the gnd and see what is which. If the pad appears to be going through the board to another pad and that pad is missing. The question becomes did the Chinese Company make a mistake on the art work and then corrected the problem on the board or somehow did the pad get lifted off in assembly and needs to be corrected? So, yes understanding the pin out of the large chip would be worth investigating. Once you know that you can just ohm out the voltage pins and gnd to verify they exist.
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Old 09-07-2015, 09:40 PM   #37
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Default Re: Help identifying a component on a wireless router.

I had to readjust your photo. I have circled the broken pad that I think you are talking about. If this is the correct I then would say yes that pad was intended to go through the board. Again if this is the right place I would say you could lightly scrap the pad on the back side of the board and then put a wire through the hole and solder it to the pad on the back side of the board and solder the other end of the wire to the shield when you attach it. It most likely be better to solder it to the shield first as it will take more heat to do this and after it cools off solder it to the pad on the back side of the board. You can use a bare wire to do this. which will also make it easier to put through the hole in the board.
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Old 09-07-2015, 09:43 PM   #38
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Default Re: Help identifying a component on a wireless router.

I circled the missing pad. I'm almost certain it's supposed to be there. I heated up the soldering station to melt the solder (I have a Weller WX2 now with a micro-soldering iron attached to it). I only had the iron there for maybe 2 - 3 seconds. I lifted up the shield until it was separate from the pad. Then I went ahead and did the opposite side. When it was all said and done, I removed the shield and my wife noticed the bad wasn't attached. It was floating in the middle somewhere. I think the trace was broke when we got it back, just that the shield was holding it in place.
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Old 09-08-2015, 12:34 AM   #39
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Default Re: Help identifying a component on a wireless router.

Quote:
Originally Posted by Spork Schivago View Post
I circled the missing pad. I'm almost certain it's supposed to be there. I heated up the soldering station to melt the solder (I have a Weller WX2 now with a micro-soldering iron attached to it). I only had the iron there for maybe 2 - 3 seconds. I lifted up the shield until it was separate from the pad. Then I went ahead and did the opposite side. When it was all said and done, I removed the shield and my wife noticed the bad wasn't attached. It was floating in the middle somewhere. I think the trace was broke when we got it back, just that the shield was holding it in place.
So how does post 35 come into play? From what I can see the hole going through the board in the upper left hand where I had previously circled is a separate connection from the upper right hand side where you say the pad came off. If you turn the board over and look at the hole going through it, now it will be on the upper right hand side looking at the back side. If you count up on from the lower right hand side of the big IC it goes to 6 pins up from the bottom. It would seem where you say the pad came off it attached the the large gnd plane on the top of the board. It is difficult for me to see because the pad is missing. If you still have the pad you could place it where it came from and see if it does not look like it attaches to the large gnd plane on the top side on the board.
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Old 09-08-2015, 09:53 AM   #40
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Default Re: Help identifying a component on a wireless router.

Here, let me try to explain it a bit different with pictures and different coloured lines. Sorry for all the confusion, my mind is a little messed up. Like I think okay, but I don't talk like I think for some reason.

In the first pic here, I know for certain the missing pad goes where the red line goes. However, I'm thinking it might also go where the light blue line goes.

I know for certain, there is continuity anywhere the green line / green squares are. I need to know if those green lines are supposed to be grounded. Somehow, they connect to the CPU. There's 0 ohm resistance from those green lines to somewhere where the red square is in the second picture. I think they might make the connection through the little blue circles on the first pic but cannot say for certain.

I was looking at a datasheet for that ASIC and from what I can see via the pinouts, there isn't a ground around there. Perhaps it isn't supposed to be grounded after all? Which makes me wonder if the missing pad on the front is really causing an issue at all or not.
Attached Images
File Type: jpg Front Board.JPG (574.6 KB, 5 views)
File Type: jpg Back of PCB 1.jpg (222.7 KB, 4 views)

Last edited by Spork Schivago; 09-08-2015 at 09:55 AM..
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