Evening all, so i'm in the process of attempting a reapir of my android tablet that fails to startup after charging via the usb port. Before i get into that in a separate post I wanted to discuss different types of pcb used in electronics; So i've attached some images of both sides of the pcb. The components are tiny so its difficult enough to determine what components they are but establishing the connection between them becuase there are very few tracks on the board. So in relation to the images can somebody help answer these questions please:-
1. The components seem to be grounded on once side to this huge ground plane and I assumed the other end went through the board to the other side but in the position they would be only seems to be another huge area of copper. take the images below, in the first one you can see the dc supply the two wires upper left, yet on the other side of the pcb image 2 theres nothing seemingly there, no solder pads, tracks. I wondered if these are over painted but it doesn't seem so.
2. The 5 pin connector is where the lion battery connects, the centre pin being the thermal sensor for control of the battery temp, either side is two positive or negative feeds. I assumed the large resistors R020 would be involved in the power circuit given their size but these are nowhere near when those +ve & -ve would emerge from the other side of the board?
3. That chip bq7510 (and i cannot determine what its is for sure) seems to be a DC to DC regulator of some kind or a lion battery fuel gauge now that has tracks going off to the small resistors and diodes either side but then the other side of these components disappears, must be through the board but to what?
4. you can probably just make out those black components labelled f1 with two bars one end. Any idea what they are?
5. You can also see tiny dots all over the green areas which i assumed were through hole but they don't necessarily correlate to solder pads on the other side of the board. On those copper circles there are punch marks which i assume are automated test points. You've got to appreciate the technology in use here, these are tiny and it beggars belief how they make probes that small in the first place, amazing.
6 Any idea how to lookup the CHT component with such little markings?
7 just for general insight, i see these smd components can be grey, brown or black. what do the body colors mean. I assume brown is a cap, grey a resistor and black a diode but could be completely wrong.
Any insights appreciated. The slight serrated edge of the board btw is a good reference point it aligns to the +ve pad (red wire) and the multi connector.
On the repair front my first port of call was to probe around the board and see where the battery supplies were going but reluctant to do this until is established what went where through fear of damaging something. I suspect the USB charging port has overloaded something so its just determining what. I'll post the circuit diagram which is hard to follow for me in a separate post but it may instant mean something to you guys.
1. The components seem to be grounded on once side to this huge ground plane and I assumed the other end went through the board to the other side but in the position they would be only seems to be another huge area of copper. take the images below, in the first one you can see the dc supply the two wires upper left, yet on the other side of the pcb image 2 theres nothing seemingly there, no solder pads, tracks. I wondered if these are over painted but it doesn't seem so.
2. The 5 pin connector is where the lion battery connects, the centre pin being the thermal sensor for control of the battery temp, either side is two positive or negative feeds. I assumed the large resistors R020 would be involved in the power circuit given their size but these are nowhere near when those +ve & -ve would emerge from the other side of the board?
3. That chip bq7510 (and i cannot determine what its is for sure) seems to be a DC to DC regulator of some kind or a lion battery fuel gauge now that has tracks going off to the small resistors and diodes either side but then the other side of these components disappears, must be through the board but to what?
4. you can probably just make out those black components labelled f1 with two bars one end. Any idea what they are?
5. You can also see tiny dots all over the green areas which i assumed were through hole but they don't necessarily correlate to solder pads on the other side of the board. On those copper circles there are punch marks which i assume are automated test points. You've got to appreciate the technology in use here, these are tiny and it beggars belief how they make probes that small in the first place, amazing.
6 Any idea how to lookup the CHT component with such little markings?
7 just for general insight, i see these smd components can be grey, brown or black. what do the body colors mean. I assume brown is a cap, grey a resistor and black a diode but could be completely wrong.
Any insights appreciated. The slight serrated edge of the board btw is a good reference point it aligns to the +ve pad (red wire) and the multi connector.
On the repair front my first port of call was to probe around the board and see where the battery supplies were going but reluctant to do this until is established what went where through fear of damaging something. I suspect the USB charging port has overloaded something so its just determining what. I'll post the circuit diagram which is hard to follow for me in a separate post but it may instant mean something to you guys.