Upgrading my old Dell, and fixing the ID chip

I have an old Dell Latitude D620 with Intel Core Duo T2300E processor, 4GB of RAM (aftermarket upgrade kit,) and nVidia Quadro NVS 110M graphics. The machine was sitting in storage for quite a while, but I suddenly I find myself in the need of a Windows-running PC with a real serial port for some maintenance work on my KVM adapter and my managed switch. So I decided to take it out of mothballs and give it somewhat a new life.

Upgrading the processor

Intel Core Duo T2300E is one of those Yonah-based chips, a 32-bit 1.66GHz dual core chip for mobile platforms and luckily socketed. Its 32-bit-ness gave me issues since I have only 64-bit operating system available now as all my other machines are 64-bit capable and have more than 4GB of RAM, requiring 64-bit OS to operate.

Inspired by the Core Duo Mac Mini upgrades I turned to Google for help. A quick Web search revealed that the the the Intel 945PM chipset used by my discrete graphics Latitude can also accept Core 2 Duo T5600, which is a full-blown 64-bit Merom chip (I tried to hunt down the faster T7600 but those are too expensive) and runs slightly faster at 1.83GHz. And the latest A10 BIOS supports those 64-bit processors as well as their advanced features like VT-x too. So I ordered one, installed it into the system, and gave it a go at 64-bit Windows 8.1 Pro. The 10-year-old laptop took the new operating system with a stride, and I think it would be able to run Windows 10 too.

Tackling the power

Just like others reported, the Dell power supply’s ID chip is fragile as balls, and got easily blown by stray EMI on the cable. Obviously as an accessory of my 10-year-old laptop I cannot RMA it. So I have to turn to hacking it somehow.

Xuan created a MSP430-based hack module and I decided to improve on top of it, emulating the easily-blown DS2502 chip with an ATtiny85 emulating it, powered with a MC34063-based SMPS to reduce its power consumption (and I really don’t trust AMS1117-3.3 or AMS1117-5.0 drawing power from a 21V rail)

M221v1 PCB layout
M221v1 PCB layout

The ATtiny85 gave me way more headroom than the MSP430G2121 Xuan used in software. This chip can emulate the full DS2501 behavior thanks to its internal EEPROM. Also thanks to its larger Flash space I can even implement some basic EDAC. And did you see that big fuse holder?

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