Re: dell precision m3800 with a locked bios

Thank you so much! I can't believe I get this help
I also have another, Dell E5470 (service tag 3VX7LC2). It has a different BIOS so it gives me a number: 3VX7LC2-E7A8. Would you have the code for this too?

Re: dell precision m3800 with a locked bios

Here is my bios dump. I just found the one on the front side of the board (UH2)....

Re: dell precision m3800 with a locked bios

Hi. My M3800 has a locked BIOS. Service tag J517YY1.
Thanks!

Re: iMac 820-2507-A (A1312) schematics and board layout

Plugged in the display temp sensor. Fans now run at normal speed. So at least something works on the logic board

The logic board seems to power off the power supply when LED 2 intermittent shutdown happens. During standby PS_ON shall be 4V and PP12V_S0_PS shall be 0V. When powered PS_ON shall be 0V and PP12V_S0_PS shall be 12V. See pinout: [url]http://hqlaptoprepair.co.uk/wp-content/uploads/2017/01/PSU-1.jpg[/url]

However, during the LED 2 intermittent shutdown PS_ON goes 4V, which leads to PP12V_S0_PS...

Re: iMac 820-2507-A (A1312) schematics and board layout

I removed the GPU and the LCD inverter board, but I get no chime. Same intermittent LED 2 going dark, then illuminating again. Fans full speed.
Checked all the caps on power supply, extremely low ESR (good) and capacitance within spec.

Any ideas?

Re: iMac 820-2507-A (A1312) schematics and board layout

Thanks. Yes, I thought so. Seems the L5720 ferrite bead is only for filtering fan noise, so shorting it for test shouldn't do any damage.

How about the intermittent shutdown of LED 2, then coming back on? What would that indicate? Could it be a short in the GPU? That the GPU is powered at this particular time, but power supply isn't able to supply due to the short, and resets or somthing? I've tried baking the GPU at 8 min 170'C, no success. I'll try again, 10 min at 200'C.

Re: iMac 820-2507-A (A1312) schematics and board layout

I got a hold of the schematics, but still missing the board. See attachment.

I replaced the Q5605, which is a 2N7002 (60V 210mA N-MOSFET) with a BSS138PW (60V 320mA N-MOSFET).

Display port connector is still missing so I'm running the iMac from an external monitor.

I tried powering her up, and there is some life in her. No chime. LED 1 is always on (power supply OK). LED 2 comes on when pressing the power button, right fan (optical drive fan) and hard drive spins up. After 3-4 seconds,...

I need schematics and board layout for Apple 820-2507-A. It's for an iMac late 2009 3.06GHz Intel Core 2 Duo (E7600).

Someone attempted repair on this and ripped the display port connector off without desoldering (probably accidentally while removing the display). Also, it has a burned inductor (L5720) (probably why repair was attempted in the first place). Due to poor storage, a transistor (Q5605) got whacked loose. It's an old iMac and slow compared to todays standards, but still performs good for designing PCB with its solid 27" screen. I really hope to get this baby up...

Re: New Members - please post your introductions here

Hello guys. Hardware engineer from Norway here. Thought I would try to fix my Mac, so in need for some schematics and layout files. Will start a new thread.