Help a newbie with his first project

[jacobtc]

Re: Help a newbie with his first project

You put a probe on pin 3 of PU100, and the second probe you put it on the capacitor, when you have zero ohm, it is the one, and at the terminals of the capacitor you find the 12 ohms.

Removing PC101, makes Pin 3 report at 180 Ohm now, is that better or worse?

[JaroTech]

Re: Help a newbie with his first project

Better, but when you put the power, what voltage do you have on pin 3 of PU100?

[jacobtc]

Re: Help a newbie with his first project

Better, but when you put the power, what voltage do you have on pin 3 of PU100?

Still only 1.2V.. oh well

[jacobtc]

Re: Help a newbie with his first project

So I will wait for the PU100 to arrive from China.. Anything else I can do in the mean time to diagnose?

[JaroTech]

Re: Help a newbie with his first project

You can try to find the capacitor CU26 which is connected to the ground, you also have PD5 diodes connected to +RTC_CELL, which is connected to CH50, CH51 and CH52 to ground. If you remove PD5 and you still have 12 ohms, then PU100 is probably the problem. Good luck.

[jacobtc]

Re: Help a newbie with his first project

You can try to find the capacitor CU26 which is connected to the ground, you also have PD5 diodes connected to +RTC_CELL, which is connected to CH50, CH51 and CH52 to ground. If you remove PD5 and you still have 12 ohms, then PU100 is probably the problem. Good luck.

So I should resolder PL101, to get 12 Ohms in Pin 3 again, and then remove PD5 and check if I still have 12 Ohms?

[JaroTech]

Re: Help a newbie with his first project

At this point, there is no need, PL101 is on the rail +3VALWP and you check the +3VLP. When you remove the PD5 diodes, you separate the other capacitors, this way you know that the problem is not these capacitors if you still have 12 ohms.

[jacobtc]

Re: Help a newbie with his first project

At this point, there is no need, PL101 is on the rail +3VALWP and you check the +3VLP. When you remove the PD5 diodes, you separate the other capacitors, this way you know that the problem is not these capacitors if you still have 12 ohms.

But I have 180 Ohms without PL101 on the rail already...

UPDATE: Removing the PD5 diode makes PU100 output 3.3V on Pin 3 now... Sooo, what happened?

[JaroTech]

Re: Help a newbie with his first project

You said in your message #41 "Removing PC101, makes Pin 3 report at 180 Ohm now" and at #43 "Still only 1.2V.." What resistance do you have on pins 1 and 3 of PD5, always without power.

[jacobtc]

Re: Help a newbie with his first project

You said in your message #41 "Removing PC101, makes Pin 3 report at 180 Ohm now" and at #43 "Still only 1.2V.." What resistance do you have on pins 1 and 3 of PD5, always without power.

It measures like there is no connection between the pins at all, maxes out my multimeter.

[jacobtc]

Re: Help a newbie with his first project

it measures like there is no connection between the pins at all, maxes out my multimeter.

double post

[jacobtc]

Re: Help a newbie with his first project

You said in your message #41 "Removing PC101, makes Pin 3 report at 180 Ohm now" and at #43 "Still only 1.2V.." What resistance do you have on pins 1 and 3 of PD5, always without power.

EDIT: Oh, did you mean between the two pins or at Ground - Pin 1, and Ground - Pin 3?

[JaroTech]

Re: Help a newbie with his first project

Sorry, but it was between pin 1 and ground and pin 3 and ground of PD5, you said you have 3.3V at pin 3 of PU100 without PD5, which means that the short is after PD5, that's why I asked you to remove it. You have capacitors connected to pin 1 of PD5, so the 12 ohms should be there too at pin 1 of PD5. Also remove the RTC cell to check the resistance.

[jacobtc]

Re: Help a newbie with his first project

Sorry, but it was between pin 1 and ground and pin 3 and ground of PD5, you said you have 3.3V at pin 3 of PU100 without PD5, which means that the short is after PD5, that's why I asked you to remove it. You have capacitors connected to pin 1 of PD5, so the 12 ohms should be there too at pin 1 of PD5. Also remove the RTC cell to check the resistance.

I only have 1 Ohms of resistance on Pin 1, however I do have about 12 Ohms on Pin 3 shortly after powering the board, this resistance seems to increase over time after removing AC however I tried removing the RTC cell, but that did not seem to change anything.

[JaroTech]

Re: Help a newbie with his first project

If you still have the 3.3V on pin 3 of PU100, then the short is on the pin 1 of PD5. You can check CH50, CH51 and CH52, maybe on of them is short to ground.

[jacobtc]

Re: Help a newbie with his first project

If you still have the 3.3V on pin 3 of PU100, then the short is on the pin 1 of PD5. You can check CH50, CH51 and CH52, maybe on of them is short to ground.

When soldering back PD5, I got 1.2V on Pin 3 on PU100 again, I will check CH50, CH51, CH52 now.

EDIT: I have absolutely no idea where CH50,51,52 is located, I'm guessing it is this area, but it is just clusters of caps... https://imgur.com/a/kPDWQ4b

[JaroTech]

Re: Help a newbie with his first project

The best way is still with the reading of the resistance to find those capacitors, if you look at page 23 of the schematic, they are in parallel, so you need to find three in parallel and they are connected to pin 1 of PD5. Don't put back the RTC cell and PD5.

[jacobtc]

Re: Help a newbie with his first project

The best way is still with the reading of the resistance to find those capacitors, if you look at page 23 of the schematic, they are in parallel, so you need to find three in parallel and they are connected to pin 1 of PD5. Don't put back the RTC cell and PD5.

Thanks! I will go back and see if I can find the caps.

[jacobtc]

Re: Help a newbie with his first project

The best way is still with the reading of the resistance to find those capacitors, if you look at page 23 of the schematic, they are in parallel, so you need to find three in parallel and they are connected to pin 1 of PD5. Don't put back the RTC cell and PD5.

Pin 1 of PD5 is short to ground somewhere. When I measure the caps, and Pin 1 for continuity, several seems "connected" to Pin 1, but that's just because it is shorted to ground...

EDIT: I just measured most of the caps in that area, and none of them seems to have both sides short to ground..

[JaroTech]

Re: Help a newbie with his first project

It will be difficult to find these capacitors.