Quadra 950 No Chime, No video

[MacLovin_0315]

Power LED comes on and there is a click from the speaker. CPU quickly gets quite hot. No POST, no video.

What should I try next?

Here is what I have tried/observed so far:

• Tried multiple RAM configurations with tested good SIMMS following Apple's Memory guidance
• There is a tested good PRAM battery in the logic board
• Tried both with the original PSU (which is at least providing good voltages) and an ATX PSU adapted following Geekdot's guide
• CPU is XC68040RC33E which the seller claimed was pulled from a working system.
  • 8 pins fell off the XC68040RC33E CPU that was in the machine. No visible corrosion; possibly I damaged it while removing it...?
• Scoped CPU pins following attached pinout diagram
  • No waveform on TK, BCLK or PCLK. There is a sine wave coming out of the nearby 66.67 MHz oscillator.
    • I am using a Zoyi ZT-703S oscilloscope, which I believe has sufficient bandwidth so I should see a 33 MHz square wave on one of the clock pins
  • VCC is +5V
  • RST is +5V
• Reset and interrupt buttons are flaky, but they are not sticking closed
• At the logic board power connector, with no PSU plugged in, there is low resistance (11-12 ohm) between +5v and ground, but maybe that is normal...?

Logic board photos below and attached. Appears to be in good condition. There was minimal corrosion here and there which I mostly cleaned up.

 

[Unknown_K]

You do have the CPU heatsink, correct? You can't run a full 68040 without a heatsink.

How did you remove the CPU? I have a black pry tool that came with a CPU upgrade and removing the Q950 CPU using it was pretty easy with no damage or broken pins.

 

[MacLovin_0315]

You do have the CPU heatsink, correct? You can't run a full 68040 without a heatsink.

How did you remove the CPU? I have a black pry tool that came with a CPU upgrade and removing the Q950 CPU using it was pretty easy with no damage or broken pins.

Yes, I do have the CPU heatsink! It is not installed since I figured it would not get very hot being on for a few seconds, and would not prevent it from POSTing. However, it does get surprisingly hot.

I removed the original CPU with a small screwdriver. I probably managed to damage it that way. If anyone can recommend an appropriate tool for a 68040, I would definitely get it.

 

[Unknown_K]

Mine came with a Newer Technologies 68040/50 CPU upgrade, but it looks like this intel one:
You want one that will fit in between the pins of a Motorola 68040