Clicking/Ticking motherboard

[p1muserfan]

My Acer M5-481 has a clicking/ticking sound coming from the motherboard with the charger plugged in until the board is started. After it starts, no more ticking. Board also won't start with both battery and charger connected. In fact, when board starts with adapter and then battery is connected, board cuts off. Guessing both problems related.

[p1muserfan]

Re: Clicking/Ticking motherboard

Trying to bump this to get some direction from somebody. Have done some more testing. PQ48 (battery fet) measures .47v in one direction in diode mode, open in the other direction (like I believe it should). However, I'm reading close to charger voltage (albeit fluctuating because of the ticking) at the positive battery terminals (with no battery connected of course). So is PQ48 the culprit here?

[highpulse]

Re: Clicking/Ticking motherboard

this is a clear sound of a leaky mosfet , chek does mosfet were you notice power on only one side and that on the outher side you got reduced voltage , chek on diode mode , and chek between D and S and S to D obviously depending on P channel or N channel , so depending on the channel type you will have value only on one side menawhile the other should give you 1 (infinite)

let us know your readings

[p1muserfan]

Re: Clicking/Ticking motherboard

PL13 (p. 31) turned out to be the source of the ticking, removed it and the noise is gone. How do I find another coil? The label on the schematic for PL13 appear to be just specs and the only marking on the part itself is 6R8. Apparently that is code for something?

[p1muserfan]

Re: Clicking/Ticking motherboard

Back at it with this board, got to figure out the problem. With PL13 removed and bench PSU set to 1V and 2A, I draw 2A and 1V on one pad (continuous current light goes on) and .96A and 1V on other pad (continuous voltage light stays on). Both PQ49 and 51 are heating up on the 2A 1V side pad. Removed both PQ49 and 51 and both pads showing 1V and 0A, so apparently those 2 are culprit (will need to order more chips). Or did something cause them to blow? Would a failing coil (PL13) make a clicking/ticking noise or could the problem still be a leaky mosfet as highpulse has suggested?

[dj_ricoh]

Re: Clicking/Ticking motherboard

ok!
good start there.
so you have lifted pl13, pq49 and pq51

pq49 1,2,3 = ground
pq51 got 5-8 with some caps to ground

pl13 short to mosfets or other side?

[p1muserfan]

Re: Clicking/Ticking motherboard

New chips for PQ49 and PQ51 but same result, board shorts immediately upon being plugged in. Reread above posts and per highpulse's suggestion (post #3), checked PQ48 in diode mode in circuit and after removing. Open both ways. Attached data sheet for fet (circuit configuration, p. 1), it should only have flow in one direction, correct? Would that explain why Pq49 and 51 are getting fried as soon as the board is plugged in if that fet is letting voltage by?

[p1muserfan]

Re: Clicking/Ticking motherboard

New PQ48, same result. Of course when the 3 chips are removed from the board , the short is gone. So something common to all 3 is taking them out. Would like to replace chips and remove charger chip but have read that's a really bad idea. Anybody with a good idea

[dj_ricoh]

Re: Clicking/Ticking motherboard

so you lifted PL13?

what side its shorted? to ic (left side ) or right side?

[p1muserfan]

Re: Clicking/Ticking motherboard

so you lifted PL13?

what side its shorted? to ic (left side ) or right side?

IC side of PL13 is shorted. When both fets and charging chip are removed from board, no short. Short only comes back when PQ49 is put back on the board by itself

[dj_ricoh]

Re: Clicking/Ticking motherboard

so on the PQ49 PAD without the fet, what pins are shorted to ground?

ASIDE from 1,2,3 that are connected to ground.

[p1muserfan]

Re: Clicking/Ticking motherboard

so on the PQ49 PAD without the fet, what pins are shorted to ground?

ASIDE from 1,2,3 that are connected to ground.

That's the mystery about all of this, no pins on either PQ48,49,51 or PU6 are short except the ones that are suppose to be (1,2 and 3 of 49 and 14 of PU6). But something is killing 48,49, and 51 as soon as board is plugged in. There has to be a short somewhere else.

[p1muserfan]

Re: Clicking/Ticking motherboard

Changed BQ24707, board no longer shorts when plugged in. Getting there, I think. Next problem is 3,5V. Only have VIN, .4v at both Boot 1 and 2, and 1.5v at PGOOD (PU1 p. 32). Chip is good, came off other board. No lines with chip removed are shorted. Where to start?

[p1muserfan]

Re: Clicking/Ticking motherboard

Finally got this board started on my bench once with screen connected. Then put it in computer case and board won't start again. Back on bench, have 3v at bios chip, 3 and 5v from coils, 3v at power switch. But RSMRST missing. What else do I need to be checking for?