Hardware Vconn input to M92T36 Explanation

bootaholic

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I'll admit when i'm out of my comfort zone... this is one of those times. Working on a console that is unfortunately liquid damaged. Initially did not have any charge; cleaned corrosion and now get the usual 0.42A however, no boot. I've seen this a few times, usually not able to fix them (I presume due to faulty main chip).

This one though has a shorted cap above the M92T36 chip. I've removed the M92T36 and the short goes away however even a new chip does not seem to resolve this issue which to me means something may still be corroded or damaged. Cap is ok. The shorted cap goes to the VCONN_IN pin (36 on M92). Can someone explain what this pin is responsible for and where this signal comes from? Is this signal passed off through some other logic gates within M92 and actual a result of another short on the board? Any help is greatly appreciated - see some photos below.
IMG_20191016_184441 (1).jpg
Capture2.JPG
Capture.JPG
 
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Agilato

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I would start with replacing those corroded caps near it, they can behave very unpredictable.
Take off that metal plate and check what's there. If liquid get there you need ultrasonic bath.
Some times liquid can short pins in usb-c port.
 
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bootaholic

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The schematic shows the input - VCONN has some sort of diode inline. Any idea where this would be?

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Agilato

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Did you checked capacitor itself for a short? Here is what i found this pin share line with an element looks like resistor, right near. Here is a pic:
 

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SolidSnakeUk89

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hmm it seems VCONN has something to do with the charging voltage I found the following references in similar chip applications:
  • VCONN Voltage - Measured on CC2 signal (pin B5) of the USB Type-C receptacle. Note - you may need to flip the USB PD analyzer over if VCONN ends up on the CC1 signal pin (A5).
  • VCONN Current - Measured across a 0.015 Ohm shunt resistor between the CC2 (pin B5) USB Type-C receptacle and the CC2 (pin B5) USB Type-C plug

so it appears this is in the 5v power rail and it appears that it uses the CC1 & 2 (config pins) to detect whether the cable is connected on each orientation.To enable Type-C cables to be reversible, the Type-C receptacle is fully symmetrical. All power, ground, and signal pins are duplicated about the symmetry axis, which allows the Type-C plug to be flipped with respect to the Type-C receptacle. The Type-C plug offers only one CC pin, which is connected to one of the CC pins of the Type-C receptacle, to establish the Type-C orientation. The other CC pin is repurposed as VCONN (abbreviation for VCONNECTOR ) for powering the electronics in the USB Type-C plug.

check this fella here... I think it is the Dc~DC buck converter for the main 5v Power rail so maybe is shorted?

upload_2019-10-19_0-44-15.png
 

bootaholic

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Did you checked capacitor itself for a short? Here is what i found this pin share line with an element looks like resistor, right near. Here is a pic:
Yep, checked cap itself by removing completely.

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Skip2000

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hmm it seems VCONN has something to do with the charging voltage I found the following references in similar chip applications:
  • VCONN Voltage - Measured on CC2 signal (pin B5) of the USB Type-C receptacle. Note - you may need to flip the USB PD analyzer over if VCONN ends up on the CC1 signal pin (A5).
  • VCONN Current - Measured across a 0.015 Ohm shunt resistor between the CC2 (pin B5) USB Type-C receptacle and the CC2 (pin B5) USB Type-C plug

so it appears this is in the 5v power rail and it appears that it uses the CC1 & 2 (config pins) to detect whether the cable is connected on each orientation.To enable Type-C cables to be reversible, the Type-C receptacle is fully symmetrical. All power, ground, and signal pins are duplicated about the symmetry axis, which allows the Type-C plug to be flipped with respect to the Type-C receptacle. The Type-C plug offers only one CC pin, which is connected to one of the CC pins of the Type-C receptacle, to establish the Type-C orientation. The other CC pin is repurposed as VCONN (abbreviation for VCONNECTOR ) for powering the electronics in the USB Type-C plug.

check this fella here... I think it is the Dc~DC buck converter for the main 5v Power rail so maybe is shorted?

View attachment 183208

Hi all,

thanks for the interesting discussion. I have severel experinces with repairing Switch boards. But one issue which i have never solved is the following:

- Switch with damaged USB Typ-C port and M92T36 , replaced both parts and the switch is still only charging in one direction, could it be that the VCONN is the responsible part for this issue ?
I haved tried to replace on severel Switch both parts second and third time but always the same affect. And the soldering points are really 100% good.

Did someone from here ever fixed this issue or is this a secret ??

Regards.
 

SheriffBuck

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Hi all,

thanks for the interesting discussion. I have severel experinces with repairing Switch boards. But one issue which i have never solved is the following:

- Switch with damaged USB Typ-C port and M92T36 , replaced both parts and the switch is still only charging in one direction, could it be that the VCONN is the responsible part for this issue ?
I haved tried to replace on severel Switch both parts second and third time but always the same affect. And the soldering points are really 100% good.

Did someone from here ever fixed this issue or is this a secret ??

Regards.

Skip2000,

I'm suffering this issue with a Switch that will only charge with the USB-C connector orientated one way. I'm at a loss as to what is going on as logic suggests that its either the M92T or the USB-C connector. I have replaced both with new 3 times with no change to operation.

Did you ever get to the bottom of this issue?

Cheers.
 

bootaholic

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Skip2000,

I'm suffering this issue with a Switch that will only charge with the USB-C connector orientated one way. I'm at a loss as to what is going on as logic suggests that its either the M92T or the USB-C connector. I have replaced both with new 3 times with no change to operation.

Did you ever get to the bottom of this issue?

Cheers.
I've been here before. Always after a USBc replacement. I have always solved it by "squishing" the USB c down with heat applied. That inside row of pads is a real pain to get good contact with.

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SheriffBuck

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I'm going to resort to some low-melt solder to see if that fixes the potential issue with fitting replacement USB-C ports.

Out of interest, has anyone had issues with variants of the replacement USB-C on eBay? Could there be some types that just don't fit well with the Switch mainboard?
 

bootaholic

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I'm going to resort to some low-melt solder to see if that fixes the potential issue with fitting replacement USB-C ports.

Out of interest, has anyone had issues with variants of the replacement USB-C on eBay? Could there be some types that just don't fit well with the Switch mainboard?
I just bought some random cheap ones on Amazon. I found tinning the pads of the USB c first helps quite a bit. I will usually remove the solder from the far locating holes first then re tin all of the pads. I'll then use the heat gun from the top side to install the USB c port. Then I'll re flux everything, flip it and apply pressure to the top side of the USB c while re heating. This allows the solder to re flow to all of the pads. Haven't had an issue since I've started doing that.

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SheriffBuck

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Low melt solder has made a big difference as I can use lower heat, thus protecting the plastic within the connector. The stuff actually gives up to 5 seconds after heat removal before it hardens, meaning I can be sure the inner pins have fused. Jury is still out on whether the joint is mechanically sound, however I used normal solder on the grounding legs for added strength.

Will check tonight to see if the one sided charging issue remains....
 
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SheriffBuck

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So one sided charging remained after refitting the port and reseating the M92 for the third time.

I was certain the CC lines were the culprit, but the buzzed right the way through to the M92 with no problems. So in desperation I removed the M92 and figured I'd see the CC1 line come through to the M92 pad with the USB connected. (5v). Nada. WTF!?

So it turns out that on the underside of the board, right next to the USB-C is an optional choke/ESD protection device sitting on the CC lines, and two convenient test pads (10 and 9) that are mislabelled on the SwitchBrew site. On another board this component was missing. I understand it's the same one that straddles the D+/D- lines on the other side. I had assumed that the CC lines went direct through to the M92, but I was wrong.

So I popped it off and voila! The damn thing starts charging on both connector orientations!

So something to watch out for. If the IC is totally damaged, then you'll get one-sided charging, or no charging at all. Worth checking before you go down the futile route if replacing USB-C connectors or M92s!

For those interested, the component is an Texas Instruments TPD2E1B06

Annotation 2020-05-14 074549.png
 
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bootaholic

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So one sided charging remained after refitting the port and reseating the M92 for the third time.

I was certain the CC lines were the culprit, but the buzzed right the way through to the M92 with no problems. So in desperation I removed the M92 and figured I'd see the CC1 line come through to the M92 pad with the USB connected. (5v). Nada. WTF!?

So it turns out that on the underside of the board, right next to the USB-C is an optional choke/ESD protection device sitting on the CC lines, and two convenient test pads that are mislabelled on the switch brew site. On another board this component was missing. I understand it's the same one that straddles the D+/D- lines on the other side. I had assumed that the CC lines went direct through to the M92, but I was wrong.

So I popped it off and voila! The damn thing starts charging on both connector orientations!

So something to watch out for. If the IC is totally damaged, then you'll get one-sided charging, or no charging at all. Worth checking before you go down the futile route if replacing USB-C connectors or M92s!

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Switch brew? I'll have to check it out. Also, really good find there. I've had several of these, next time I'll look for this.

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Ra-D-OH-3H

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Hello. The symptom is that the console is charging the batteries, there are no short circuits on the P13USB or the M92T36. Tensions are present. the only anomaly I noticed was the low voltage on pin 36 on the M92T36 - namely around 1 volt instead of 5v. You can see that someone either replaced the P13USB or soldered it because the capacitors were shifted. the second thing that I noticed was a bent few pins in the LCD connector, which I have soldered at the moment. The console doesn't go into RCM, no backlighting, it just doesn't do anything but recharge the battery. When you press the power, the consumption changes, so something is still alive. The question is whether it makes sense to repair it or look for a mainboard. Sorry for my English.
 
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CHTechRepair

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Hello. The symptom is that the console is charging the batteries, there are no short circuits on the P13USB or the M92T36. Tensions are present. the only anomaly I noticed was the low voltage on pin 36 on the M92T36 - namely around 1 volt instead of 5v. You can see that someone either replaced the P13USB or soldered it because the capacitors were shifted. the second thing that I noticed was a bent few pins in the LCD connector, which I have soldered at the moment. The console doesn't go into RCM, no backlighting, it just doesn't do anything but recharge the battery. When you press the power, the consumption changes, so something is still alive. The question is whether it makes sense to repair it or look for a mainboard. Sorry for my English.

You will likely need a donor to figure this out without just blindly replacing components. If your battery is charging but the console has no power I wrote up a thing about what I look at in these situations here. MAXX77620 is the most likely candidate if there is no other visible or measurable problems, but there's a laundry list of things that are needed to even get to RCM.
 
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Ra-D-OH-3H

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Thanks CHTechRepair.
I have another working console, but it has a different motherboard. so not everything can be compared.

I will write if I can solve the problem.
 
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CHTechRepair

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While searching, I noticed that I do not have 1.8V power on the emmc connector.Does anyone know which IC considers this voltage.

MAX77620 regulates the 1.8v rail. Output can be measured on one of the large inductors beside the IC. It also outputs many other 1.xv rails. Can be a bad coil, or bad MAX77620.
 
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