Centris 650: Operation "Oscillator Socket Hack"

[tecneeq]

So i pulled the board out of my Quadra 650 to overclock it from 33 to 40MHz. Wanted a socket for the oscillator too, in case i want to try 44MHz some day. Enjoy my journey! Mind you, i am half blind.

The idea was simple, unsolder the old oscillator, solder in a socket and plug in the new oscillator. Easy:


I dusted off the board and removed the heat sink to apply new heat transfer paste:


Then i located and lubed the old part:


Obviously i burned my Nubus slot like a noob:


The socket i had planned didn't work, not enough space between the Nubus socket and the part to get it done, so i cut one of those guys up:


The other part. This may look funny, but it's actually robust enough to not move when you flick a finger against it:


Thought about a socket tower for a second, but ended up with this:


Here is what the pins are, information no other guide seems to provide. First the old:


And the new part:


I then connected the power supply and the speaker to the board, turned it on and got a bong! Seems to be working.

Time for a piece of chocolate and a cup of tea.

 

[Phipli]

Yeah, I think if I was doing it again I'd either make an adapter PCB that was easier to solder in, or use solder paste. Or both.

It is a very small gap between the socket and the Nubus slot. It is one of the most tricky clocks I've replaced, possibly worse than the clock on the 475 that is right up against the VRAM slots.

 

[tecneeq]

The board gets transplanted into a Quadra 700 case right now, so this particular port isn't useable anyway. Seems to be useable still, if one cuts free one or two holes.

The solder pads are large enough to put down a good thick blob of solder and go from there, i feel this is very robust, even if you would ding it with a card or something.

 

[joshc]

What’s the reason to use a socket at all other than experimenting with speeds? I used an equivalent surface mount component when I did my 650 board.

 

[Phipli]

What’s the reason to use a socket at all other than experimenting with speeds? I used an equivalent surface mount component when I did my 650 board.

You've answered your own question there I always fit a socket so I can revert to stock or push the clock harder on a whim.

But also, I have a 601 card that wont run at 80MHz, in a machine that the 040 will do 40, so I swap the speed depending on what I'm doing.

 

[joshc]

Fair enough. With these it might be easier to solder bodge wires onto the solder pads and then locate the socket somewhere else. Not ideal but gets around trying to fit a socket directly next to the NuBus slot.

Also, I found when I socketed the oscillator on my Quadra 700 that the oscillator would unseat itself whenever the machine was moved unless it was taped or glued down.

 

[tecneeq]

I think it's fairly common that 42 or even 44 MHz works. Have to order the oscillators and give that a go.
So far it's smooth sailing, didn't notice a single problem with 40MHz.