Help me understand this schematic

[IamPritesh]

Can anyone please tell me the source of +5V_VCC1 on the schematic attached with this post.

[ktmmotocross]

Re: Help me understand this schematic

looks like its just badly marked +5V switched from +5V_S5 by PQ62

just diode probe its trace from it

[piernov]

Re: Help me understand this schematic

As per datasheet, VCC (pin 3) is connected to PVCC (pin 19, VDD on schematics) through a 10 ohm resistor internal to the PM6686 chip.

[IamPritesh]

Re: Help me understand this schematic

looks like its just badly marked +5V switched from +5V_S5 by PQ62

just diode probe its trace from it

I was hoping that this VCC input for PU9 is generated well before the voltage reaches the coils PL13 and PL14.

maybe I am wrong...

[IamPritesh]

Re: Help me understand this schematic

As per datasheet, VCC (pin 3) is connected to PVCC (pin 19, VDD on schematics) through a 10 ohm resistor internal to the PM6686 chip.

That is some awesome information. In that case Pin19 is connected to LDO (6237LDO5 on schematic). So if I have 5V LDO , then I should also have the same on VCC (Pin3) but that does not seem to be the case if I recall well. I have 5V LDO but no voltage on +5V_VCC1

[piernov]

Re: Help me understand this schematic

Maybe PC191 is shorted or PU9 is bad then.

[Udemzy]

Re: Help me understand this schematic

No voltage on pin2 and pin 32? Did you check impedance of the pin? Cos Ton will automatically generate from the ic.

Check impedance otherwise replace ic.

[IamPritesh]

Re: Help me understand this schematic

IC replaced with a new one. Now I have LDO and 3VPCU

BUT I do not have +3V , no MAIND signal and no 5V as well.

Please refer to the image. I am having a hard time trying to figure out why 15VCPU is 10V .

Please note PC191 is currently removed and I feel it should make no difference.

[IamPritesh]

Re: Help me understand this schematic

Any help what could be causing 10V instead of 15 volt on 15VCPU

[khaahk]

Re: Help me understand this schematic

Missing 5V from PU9?
Do you have s5_on? To explain missing 5V from PU9.

Dickson charge pump
https://www.youtube.com/watch?v=I4ED_8cuVTU

[IamPritesh]

Re: Help me understand this schematic

Missing 5V from PU9?
Do you have s5_on? To explain missing 5V from PU9.

Dickson charge pump
https://www.youtube.com/watch?v=I4ED_8cuVTU

There is no S5_on. S5_ON is coming directly from SIO chip and this SIO CHIP does not have any VDD voltage.

SIO chip does have VCC voltage coming from 3VPCU. I was wondering if VDD is essential on SIO chip before S5_ON is generated ?

[khaahk]

Re: Help me understand this schematic

SIO VDD should come after maind signal, which in turn seems to come after run_on signal.
Does SIO give 3V to power button? After pressing power button does it give impulse to PCH (EC_PWRBTN# goes low for a short time)? Does PCH respond with pulling SLP_S4 and S3 high?
How much current is drawn before pushing power button and does it change?
Resistances on +3V and +5V rails - maybe there is low resistance after PQ62 and PQ45?

[IamPritesh]

Re: Help me understand this schematic

SIO VDD should come after maind signal, which in turn seems to come after run_on signal.
Does SIO give 3V to power button? After pressing power button does it give impulse to PCH (EC_PWRBTN# goes low for a short time)? Does PCH respond with pulling SLP_S4 and S3 high?
How much current is drawn before pushing power button and does it change?
Resistances on +3V and +5V rails - maybe there is low resistance after PQ62 and PQ45?

There is only 1.5 volt on power button. Bios Chip pin1 has same 1.5 volt on pin 1 and around .6 volt on pin 8 of bios chip
There resistance on PQ62isa and PQ45 output is around 300 ohms.
What could be causing this, i am running out of ideas what to check.

[khaahk]

Re: Help me understand this schematic

How much current is drawn from adapter before pushing power button?
300 ohms seems a little low but not sure.

[IamPritesh]

Re: Help me understand this schematic

How much current is drawn from adapter before pushing power button?
300 ohms seems a little low but not sure.

Using a DC power supply it shows 0.03 Amp when I plug in the Adapter.

Could this be a case of faulty SIO chip ? Anything I can do test this chip ?

[khaahk]

Re: Help me understand this schematic

0.03A is a bit too much, but too little to find anything by heat i think.
Check if sio tries to read it's program from KU3, pin 2,5,6.
You can also inject directly 3v after PQ45 to see if anything heats abnormally.
Seems like a hard to find fault you got there.

[khaahk]

Re: Help me understand this schematic

Check PD27 & PD28 just in case 15V has to be also present at first.