I could use a small soldering iron tip and put solder over all the pins to melt them all at once to remove the IC then use solder brade to clear the pads of excess solder nice and flat ready for the new IC then solder each pin, that's what I could do as I don't have access to a hot air station.
Though it depends how it is anchored, is it anchored by dedicated anchor points underneath or just anchored by the pins?
The IC may be healthy. Using this method, you damage the IC. and you may also damage the pads on the board. I recommend not to use it. Since the pads are almost under the IC, the soldering iron can not do it properly.
The IC may be healthy. Using this method, you damage the IC. and you may also damage the pads on the board. I recommend not to use it. Since the pads are almost under the IC, the soldering iron can not do it properly.
Hopefully their're both healthy , I'm not sure where I'll get access to a hot air station without having to paying a high price as I can't spend too much more on it.
My digital multimeter has a 4 digit display, when testing the PL703, PL704, and PL705 the display shows "000.9mV", is that 900 mili volts or 900 micro volts?
pin 25 and 26 of PU701 have got 2.5v whereas they are assumed to have 5v.
please unplug the laptop and measure resistance between the following pairs of points:
- between pin25 of PU701 and pin8 of Q26 (one probe on pin25 of PU701 and the other probe on pin8 of Q26)
- between pin25 of PU701 and pin1 of Q26
- between pin26 of PU701 and pin1 of Q26
Then, turn the laptop on and measure voltage on the following points:
- pin1 of Q26
- pin8 of Q26
pin 25 and 26 of PU701 have got 2.5v whereas they are assumed to have 5v.
please unplug the laptop and measure resistance between the following pairs of points:
- between pin25 of PU701 and pin8 of Q26 (one probe on pin25 of PU701 and the other probe on pin8 of Q26)
- between pin25 of PU701 and pin1 of Q26
- between pin26 of PU701 and pin1 of Q26
Then, turn the laptop on and measure voltage on the following points:
- pin1 of Q26
- pin8 of Q26
Resistance between pin 25 and pin 26 on pin 1 seems high, is the pin layout in the picture correct?
(PU701)pin25 on (Q26)pin8 - 4.72 k ohms
(PU701)pin25 on (Q26)pin1 - 1.1 ohms
(PU701)pin26 on (Q26)pin1 - 0.4 ohms
Q26
pin8 - 5.13V
pin1 - 2.574V when not beeping, flashes between 2.574V and around 2.501V when 7 beeps are sounding
these measurements show the +5VS voltage rail on the board is not correct. this can be the main cause of all the problems. so you need to do more measurements on +5VS.
first measure voltage on pin4 of Q26 after turning on.
these measurements show the +5VS voltage rail on the board is not correct. this can be the main cause of all the problems. so you need to do more measurements on +5VS.
first measure voltage on pin4 of Q26 after turning on.
Q26
pin 4 - 3.367V when not beeping, flashes between 3.367V and around 3.301V when 7 beeps are sounding
unfortunately, +5VS is connected to many components and tracing it takes many measurements.
to start, measure voltage on pin 1,2,6 of Q285 after turning on.
unfortunately, +5VS is connected to many components and tracing it takes many measurements.
to start, measure voltage on pin 1,2,6 of Q285 after turning on.
Edited measurements
Q285
pin1 - 0.0mV
pin2 - 0.1mV
pin6 - 2.574V when not beeping, flashes between 2.574V and around 2.495V when 7 beeps are sounding
there is a resister with marking of 471 on it near Q285.
please measure voltage on pin 1 and 2 of it after turning on.
Resister with marking of 471
pin1 - 2.574V when not beeping, flashes between 2.574V and around 2.495V when 7 beeps are sounding
pin2 - 2.574V when not beeping, flashes between 2.574V and around 2.495V when 7 beeps are sounding
all are OK except +5VS.
you found the faulty voltage line so far but not the faulty component yet.
Repairing the +5VS line needs more thinking and analysis for tomorrow.
remove solder on PJP203 or pjp204 located near 3.3 and 5 volts regulator in the lower part of mainboard (down from keyboard connector, in that extended part of mainboard)
remove joint and measure if one side has 5 volt or 3.3 volt.
as in the attached picture pjp should be one of the marked red, while the green is the 3.3 alws and 5 alws volt regulator.
remove solder on PJP203 or pjp204 located near 3.3 and 5 volts regulator in the lower part of mainboard (down from keyboard connector, in that extended part of mainboard)
remove joint and measure if one side has 5 volt or 3.3 volt.
as in the attached picture pjp should be one of the marked red, while the green is the 3.3 alws and 5 alws volt regulator.
Do I have to remove both of them to test each side as they both connect to the same point? Like this?
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