Recent content by melvinvdb

A yes of course... Thanks will remember that for in the future.

So powering the board without u7800 will blow the CPU? Why? If the MOSFET isn't controlled it won't open right? With high-side MOSFET you mean like u7900, u7960, u8050, u8000, u7220, u7420 etc right? Any safe way to check before proceeding and making this mistake a second time?

Bumping an older thread. I removed U7800 and applied USB-C power. Some smoke came from somewhere. Than I noticed PPBUS_G3H got shorted. U7800 was still removed. I've injected 5v on PPBUS_G3H with 0.5a. Only thing that heats up is the PCH/CPU. Is the PCH now dead? I just read I shouldn't inject...

Well I've been able to cut the line between U7650 and the rest. U7650 s5_pwrgd slowely increase to about 2v which is normal because it is missing the pullup resistor. The line that contain U7800 U5000 and the resistor R7802 is still low @ 0.074v. The resistor looks good and I don't see a short...

Well I said earlier that I've replaced u7650 twice already with the exact same results. So I don't think u7650 is pulling the line low. I've found a trace to cut s5_pwrgd from the smc. May take that approach first. Will check again for a s5_pwrgd trace by u7650

Reflow didn't help. Do you think injecting 3.3v with a low current is a good idea? If I need to replace u7800 this chip doesn't have firmware like u5000 right?

Hmm well there is no easy place to cut for pin 20. Measured R7802. Has 3.3v on one side and is around 95kohm. So pullup should be working. Anyway S5_PWRGD is now definitely the problem to solve. There is corrosion around U7800. Will reflow it tomorrow maybe it is pulling it down.

Hi guys, I'm having a strange issue with a liquid damage 820-00239. Charger does switch to 20v with 0 current draw. PPBUS is 13v. P3V3_S5 = 3.3v. PP5V_S5 = 5v. No S4 voltages. No PM_SLP_S5_L and lower is not present. So I checked S5_PWRD which is 0.07v. Than I started checking on U7650: -...

So I've done some digging. UART: 1.2us for one bit means a UART baud rate of 833333. High but not impossible. This would make sense because connected to my computer I was getting different data transfers on every baudrate. So 833333 seems possible. Transfers are send as pairs with some fixed...

I'm not at location at the moment so I can't double check but I've previous measured the following: - On UART TX line was activity - On UART RX line was activity (so they both communicate. Was unable to see at what baud rate though) - On the SPI lines to the ROM chip was also activity Will...

I don't have them available but can order them. Will take two week though. So at this point I think that would be the best option. Also If that doesn't work I'm thinking of replacing the SMC. I have a china donor board with the same 820-00840. Also on ebay there are SMC chips for sale...

Ok I've removed U8510 and replaced it with a bypass resistor just for the SMC_RESET circuit. When the 20v works I'll place a u8510 from a donor board. Anyway the 1v issue is gone. Still no difference on the other rails. Still nothing on PPBUS_G3H.

Sorry damn I'm making mistakes in documenting it here. SMC_RST_IN high to 3v SMC_RESET_L than goes low. BUF_SMC_RESET_L also goes low. When SMC_RST_IN power is removed: SMC_RESET_L goes to 3v BUF_SMC_RESET_L sometimes stops at 1v What do you mean with discard U8510? What does it do? In the...

Well nothing interesting is connected to SMC_RST_IN or SMC_LSOC_RST so i've applied 3v to them (no keyboard connected). Result is SMC_RST_IN low, SMC_RESET_L low and BUF_SMC_RESET_L low. No voltage at PPBUS_G3H. Very interesting things happen though when I disconnect the 3v. SMC_RESET_L gets...

No difference. SMC_RST_IN is also around 90k. SMC_RST_IN stays LOW which seems fine..