FPU socket replacement in Falcon

[Steve]

Hi all,

I was attempting to try out @dml's amazing SVO Minecraft-like Engine for the Falcon 030. But upon starting the program I saw:

in game crash.jpg (282.18 KiB) Viewed 629 times

loading.png (1.48 MiB) Viewed 629 times

I tried transferring the files in different ways, without any luck. Eventually dml suggested I try the DSPbench and FPUtest. DSPbench passed, but FPUtest failed:

failed fpu test.jpg (424.42 KiB) Viewed 629 times

I then inspected my FPU:

the suspect.jpg (347.67 KiB) Viewed 629 times

Firstly I noticed a hair-line crack in the socket, when removing the FPU the crack widened. Also - a leg of the socket fell out when removing the FPU!

FPU leg.jpg (29.31 KiB) Viewed 629 times

So I could already see what my bank holiday monday was going to be all about....

Firstly I designed a 3D printable bracket for the FPU (will be attached here to download as STL:

3d printed bracket.jpg (117.86 KiB) Viewed 629 times

FPU bracket.stl

(1.64 KiB) Downloaded 7 times

Luckily I had a socket replacement already on hand:

new socket in bag.jpg (383.61 KiB) Viewed 629 times

I used chipquick flux and low-melt solder for the original socket legs, then applied heat with my heatgun to remove the socket easily. (don't worry about the 'bodge wire' inside the socket, it's from a trace repair)

prepped and ready.jpg (478.09 KiB) Viewed 629 times

It came off nicely:

socket removed.jpg (410.25 KiB) Viewed 629 times

Now to solder the new socket:

soldering new socket.jpg (465.05 KiB) Viewed 629 times

Soldering finished, I then checked all pins for shorts with my multimeter:

finished soldering.jpg (442.94 KiB) Viewed 629 times

FPU installed with my bracket for extra strength:

final fpu and bracket.jpg (449.82 KiB) Viewed 629 times

FPU test passed!

working fpu test.jpg (504.21 KiB) Viewed 629 times

SVO works!!!

working svo.jpg (328.54 KiB) Viewed 629 times

[exxos]

Nicely done!

[leonk]

How did you solder on that new socket? It's designed to be installed using solder paste and not hand solder. That's why when some try to hand solder it, they punch out the middle support plastic holder. I see this all the time with Neo Geo MV1C/1B UNIBIOS 40 pin adapters. Even under a microscope, it's almost impossible to solder all those pins by hand.

[HigashiJun]

Neat and nice repair !

[mikro]

Very nice Steve, great job.

[Steve]

How did you solder on that new socket? It's designed to be installed using solder paste and not hand solder. That's why when some try to hand solder it, they punch out the middle support plastic holder. I see this all the time with Neo Geo MV1C/1B UNIBIOS 40 pin adapters. Even under a microscope, it's almost impossible to solder all those pins by hand.

Thanks for the compliment, it was very difficult as I don't have a microscope (I just use magnifying lenses) The only way it was possible is probably due to me having a very fine soldering tip. The forum post made it look easy, but there was a lot of swearing in-between photos ... coincidentally I do have solder paste, but I haven't had good experiences using it previously, I often end up with tiny solder balls left over in random places and I was worried some might have gotten stuck underneath the plastic centre of the socket, potentially causing issues, so I opted to hand solder.

Thanks everyone else for the kind feedback

[rubber_jonnie]

Nicely done.

I did install a CPU socket on a Mac Classic once and I cut the centre square out to allow easier soldering and it worked very well.

Of course it can lose a little strength by doing so, but in your case with the stiffener around I doubt it'd be a problem.

[Badwolf]

Very nice work.

My Falcon's FPU socket replacement was my first crack at proper electronics work back around 2013. It didn't go well.

I didn't have the right tools. I didn't know what I didn't know. I made things worse and ended up soldering the FPU direct to the mobo, IIRC.

It wasn't until I started work on DFB1 that I decided to revisit it and could make good some of the mess I'd created with better tools and more practice. Even then I went for the punch out the bottom square option.

This, on the other hand, is how it should be done.

BW