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Thanks for your response. I have implemented the LED test, connecting the light and resistor between ground and pin 5 of U6100 (SPI_MLB_MOSI) which I believe according to the data sheet in the data line in. The LED indeed lit up for a second, then turn off for a millisecond then back on for a...

820-00875 Hey, I am trying to determine the source of this issue. Symptoms: A few vertical colored lines on the left side of the screen totalling less than 1mm in width Sometimes horizontal lines appear and disappear near the top of the screen Screen brightness level fluctuates...

I replaced the clock chip U2700 and unfortunately there is seemingly no change in voltage anywhere. Any other ideas?

Well I'm not sure...and I'm also inexperienced so I don't know - does testing or replacing the clock chip sound like a good idea to anyone else? I'm at a loss with this one. The Fluke multimeter is able to measure frequency. SYSCLK_CLK25M_SB measures 0 Hz

Should I be looking at the tantalum capacitors like C9560? C9560 has only 115Ω of resistance between its pins whereas other capacitors on the board seem to have much more; should this be concerning?

Unfortunately no and no

Thank you for your responses. This board DOES have a green light from the charger, but when I trip the Power On Points, there is no fan spin / no power. I am going down the list of power rails listed in the schematic in order: PPBUS_G3H 12.6V present and accurate PPBUS_CPU_IMVP_ISNS 12.6V...

Though I see the notation in the schematic, I cannot locate the voltage divider nor therefore the source of pp1v05_s5; can anyone help with this? Additionally, I am having trouble detecting the source of the short on pp1v05_s0...I measured it in like a bazillion places and every reading was...

2informaticos is correct: U7740 as well as neighboring U5101 and C7741 and U3714 are not present on the board. Measured at R1120 in the same area, PP1V05_S0 is shorted (resistance to ground 13Ω). I do have the schematic in front of me but this rail shows up so frequently I'm not sure where to...

Sorry I am still learning... So this mb gets green light on charger but no boot / no fan spin. G3H present PP3V42_G3H present PP3V3_S5 present PP5V_S5 present PP1V05_S5 missing I see that it is linked to the cpu but what creates PP1V05_S5? It looks like this one has not been opened before...

Hi! Green light IS present on charger. No boot. A1278 820-3115-B No 3 volt rails present PPDCIN_G3H is present at r7010 CHGR_ACIN not present CHGR_ACIN has resistance of only 2.5Ω to ground so it’s shorted right? Replace U7000? Thank you!!

Should I go ahead and replace the clock chip just to see? Maybe I'll just set this one to the side for a bit and stays board? I know this problem in particular can be a challenge to diagnose I could just return to it when I'm more well versed but any suggestions welcome

I should reiterate this is a quarter fan spin issue

Ok I got my hands on a proper multimeter...no O-scope yet but I'm hoping we can make some progress using the MIN MAX recording function on this Fluke 87 III...the response time is 250 µs or100 ms...is that passable for now? I am reading minimal pulse at L7510: it fluctuates +/- 0.2V on 100ms...

:rolleyes: oops...it won't happen again! I'll chalk that L up to the cost of learning this trade...and me being an idiot...and this being my first board...let me just replace that meter...needed a better one anyway...nothing to see here...

Could I be affecting the current by measuring it, like with quantum mechanics?

As in there is a path of low resistance (short?) from that pin to ground, ie the multimeter beeps in diode mode...I wasn't sure if that was relevant when you mentioned a short relating to this circuit. My meter shows some voltage activity on this coil right when the connections are made and...

U2750 Pin5: 3.3V Pin1: 0-3V flux Pin2: 0.02-0.5V flux Pin4: steady 1mV Does this mean U2750 is malfunctioning?

Yes! R7402 reads: Pin1 (CPUIMVP_TON) reads 8.36V but abruptly drops every few seconds then rises and holds at 8.36V Pin2 (PPBUS_S5_HS_COMPUTING_ISNS) is a steady 8.44V R7402 measures .0911 MΩ Pin2 on R7402 has continuity to ground and Pin1 does not