Sony 7182M no power at all

[rippergr]

Hello,
I have a sony 7182M which doesnt power on. I checked of course ac adaptor and jack.
I measured mosfet pq24 & pq25 which are ok also on pu1 I have on vref 3.3V
Can someone tell me how to continue checking because I don't know how to move on and if someone can give me general directions on such cases (I have basic-medium skills on reading schematics) what to check first(voltages, fuses, vref etc). Is there an online guide or a book to start with?
I am attaching schematics and both side board

Thanks in advance.

[p1muserfan]

Re: Sony 7182M no power at all

Do you know if just plugging in board shorts out adapter? If it does you gotta fix that first. If you have no dead short, check for 3.3 and 5v always on voltage at PU11, pins 19 and 21, page 55

[jagga]

Re: Sony 7182M no power at all

system disable
service tag number - 5N5QRZ1
dell laptop.. i need the password for my laptop if anyone can help please email me at samreetjatti@gmail.com

[rippergr]

Re: Sony 7182M no power at all

I checked pu11 but I have 0,6v or 0,04v (I think it is because I am using a pin to my multimeter and may touching it )
If I measure the adaptor when I plugged it in it gives me 19V. I don't know if that is what you said to check.

[xxxvirus1987xxx]

Re: Sony 7182M no power at all

the pu11 is the system Ic the voltage are comming frorm pq24 and pq25 if have 5 volts and 3.3v meanign the power section is good..check backward for some other components problems..
waht is your reading at pq24 and 24 all pins pls post...

[rippergr]

Re: Sony 7182M no power at all

Mosfet PQ24
1,2,3,4 = Voltage 19,27V
5,6,7,8 = Voltage 19,81V

Mosfet PQ25
1,2,3,4 = Voltage 19,27V
5,6,7,8 = Voltage 0V

I measure again PU11 more carefully and the voltage is 0.60V on pins 19 and 21, also I checked PL14 which has 0V on both sides and PL15 which also has 0v on both sides. So I am guessing it is something before those.

[xxxvirus1987xxx]

Re: Sony 7182M no power at all

can u check the resistance between of pu11 of pin 19 to 21 with respect to ground..
u can isolate load to check if the vcc of pin 19 and 20 are exact 3.3 and 5volts....if unloaded then u get 3.3 and 5votls the prolem is pu11 or some components connected to pu11.
waitng for others to help..

[rippergr]

Re: Sony 7182M no power at all

I didn't understand how to check resistance between pin 19 and 20 but I checked pins 17-22 and I have no voltage in pu11.

[rippergr]

Re: Sony 7182M no power at all

I measure TP145 (which should have 3V) no voltage. TP152 no voltage. TP156 no voltage.

[p1muserfan]

Re: Sony 7182M no power at all

I didn't understand how to check resistance between pin 19 and 20 but I checked pins 17-22 and I have no voltage in pu11.

Checking resistance between pins and ground simply means putting your meters - probe on ground and your + probe on the pin you're checking. Select ohms on your meter and if the reading is 0, that pin is shorted to ground. Pin 22 is your input pin to TPS51120 (your 3.3 and 5v regulator chip), so if you have no voltage there you need to work backwards to find where the "break" is. You said you have no voltage on PQ25 pins 5,6,7,8 so check PR9. Check each side of that resistor for short to ground. Do you get voltage on both sides of PQ5 with the battery connected?

[rippergr]

Re: Sony 7182M no power at all

ok I have 2,46ohm in pin 19, 3,74 ohm in pins 20 & 21.
I don't have battery for the laptop and I rellay don't care to work with battery.

[p1muserfan]

Re: Sony 7182M no power at all

ok I have 2,46ohm in pin 19, 3,74 ohm in pins 20 & 21.

O.K., so those lines aren't shorted. You said in an earlier post that you have no voltage on pins 5-8 on PQ25. That's a problem because the voltage is suppose to go through PQ25, through PR9 to DCBATOUT to pin 22 of PU11. Use your meter in diode mode and check PQ25 (+probe on 5,6,7, or 8 -probe on 1,2,or 3. You should read about .5v. Switching the probes around should read out of range.

[rippergr]

Re: Sony 7182M no power at all

I measure PQ25 in diode mode and with +probe on 5,6,7,8 I have readings .505 in all pins except 4 which is gate. if I switch the the probes reading is out of range.
I don't have voltage readings on resistor PR9 either so I guess it is somethin before. Can you tell me what is before PR9 to test?

[p1muserfan]

Re: Sony 7182M no power at all

The only other suggestions I have is to check PC25, only 1 side of that capacitor should be short to ground. If that's not the problem follow DC_IN_R off of pin 5 from PQ25 to page 60, "system SCP protect" circuit. Maybe PD8 is blown? If you had an adjustable power supply you could put 2v and 1a to pin 5 of PQ25 and whatever is bad would heat up. That's the quickest way to find a bad component.

[rippergr]

Re: Sony 7182M no power at all

I am attaching a picture of the board. Can you please tell me which one could be PC25 because I can't find it and I think it maybe not writen on the board and could you indicate me which one is PR9 becuase I measure the big one but now that I saw it more careffuly maybe this isn't PR9

[p1muserfan]

Re: Sony 7182M no power at all

Don't see PC25, not everything is labeled, it should be in PQ25 PR9 area. PR9 is just below PQ32 with the marking RO15 on it. But if you have no voltage on the one side of PQ25 you won't have anything on PR9 either. PC25 is gonna be small, like PC194 which is right above PQ32

[rippergr]

Re: Sony 7182M no power at all

PD8 in diode reading is ok. I haven't test to see if there is voltage but I think it is not nesecary since there is no voltage in PQ25. Unless the voltage goes from PD8 to PQ25.

[p1muserfan]

Re: Sony 7182M no power at all

What is the resistance to ground (ohm) reading of pins 5-8 on PQ25?

[rippergr]

Re: Sony 7182M no power at all

What is the resistance to ground (ohm) reading of pins 5-8 on PQ25?

On 20K its 0.39 ohm

[rippergr]

Re: Sony 7182M no power at all

I measured TP158 (page 54 on schematics) which is next to PQ5 and I have voltage 0,38V (multimeter set to 20V )
I can't find PC25 and PC18 anywhere to measure voltage on those capacitors. I think the problem is on one of them because I have voltage on pins 1,2,3,4 on PQ25 and no voltage on 5,6,7,8 and PR9.
Can someone see the schematics and the picture and tell me how can I find those two?