Socketing a PROM is so precise and exactly the same for every S3 owner that I feel comfortable writing a guide for this process. This is forum for hobbyists, yet it is somewhat rare for computer hacking skills and electronic soldering skills to coexist in the same hobbyist.
To socket an S3 I use the following tools and supplies
- 30W / 15W switchable radio shack soldering iron with a sharp and well tinned tip
- Fine electronic solder
- About 10 cm of ChipQuick alloy
- Radio Shack desoldering braid
- ChipQuick flux
- 3M surface mount PLCC32 socket 3M part number 8432-21B1-RK-TP Get it at mouser.com
- Utility knife
- Small needle nose pliers
- A dozen Q-tips
- Isopropyl alcohol
- Magnifying glass
- Ohm meter to check for shorts and mis-soldered pins
The best DDB threads for general tips are
This one in the Buy/Sell forum
This one in the S2 Support forum
Both threads include many approaches and methods. Here is my method:
After removing the hard drive and getting the box on a bench with bright lighting,
1. Prepare the TIVO.
Get the box on a bench with good light and ventilation.
Remove the hard drive.
Remove the clock battery.
Take static electric precautions. Either use a ground strap (I connect it to my ankle to keep my hands free) or get the room humidity over 50%.
Tape off the area around the prom to prevent possible splatter contamination / shorting of nearby parts
2. Follow the ChipQuick instructions to remove the PROM
- Apply a bunch of flux to all pins
- Melt a bunch of the alloy to bridge the 8 pins on each side.
- Rapidly heat different sides with iron until the chip slides around
- Lift the chip off with a pair of small pliers
- If you lift a pad, this is not the end of the world, extremely delicate surgery might be able to save the device, by transplanting a few stands of copper from a de-soldering braid onto the trace to form a new pad. Best not let this happen though
3. Clean the Pads
While melting the remaining alloy, use Q-tips to push the alloy / solder mixture off the pads. After the blobs harden remove them with fingers or tweezers.
Using plenty of desoldering braid laid flat across a row of pads heat the solder and pad through the braid. Do not linger in any one place long. Be sure to run a fine balance between getting the pads clean enough that good joint is possible and between overheating the pads detaching them by melting the underlying PCD
Clean the pads and area with Q-tips and alcohol. Special lint-free versions of the classic q-tip may be desirable since leave less mess.
4. Clean the Old Prom
The ChipQuick designers assume the old component will be trashed and the old prom is left with all the pins bridged. To remove the alloy:
Set the iron to 15W
Grasp the PROM between thumb and forefinger so that one row of pins is in the clear.
Heat that row of pins all at once with the side of iron tip until the alloy melts
Quickly hit your wrist / edge of your palm against a table top
DO NOT HIT THE PROM AGAINST THE TABLE. Hold on the prom the entire time.
The liquid alloy should fly off the pins and splatter on the table. Put down some cardboard to catch the mess.
Rotate and repeat until all pins are isolated. If a second round is needed a little flux can help the process
5. Prepare the Pads.
Apply a load of flux the pad area.
Carefully place a very small amount of solder on each pad. To do this ...
Touch the iron to the solder to melt a droplet on the tip of the iron
Touch the iron to the pad to transfer the solder to the pad
Repeat until all pads have a small bubble of solder on them
6. Prepare the socket.
Using a sharp knife cut the bottom out of the socket.
Cut the plastic lines as close to the connectors as possible
Do not lose the bottom piece, it will be needed later!
Use the tip of the knife to pop out the remaining plastic between the connectors.
Cutting the bottom of socket does not significantly weaken it, once soldered it is very strong. Having the bottom out makes the job of soldering much easier and allows for easier testing of the circuit if there is a problem later
7. Solder the socket
Align the socket carefully on the board
Triple check the socket is aligned properly
Press the socket down until the 'feet' are resting on the pcd, the pins are springy and will bend up away from the solder pads you laid down.
When you are sure the socket is perfectly aligned touch the iron tip to one pin. The pin will melt the solder under it and push down to the pad. Once you remove the iron the solder will cool and lock that pin in place.
Repeat with a pin on the opposite side to ensure good alignement
Solder two pin on each side
Finish soldering all pins
Triple check every solder connection with a magnifying glass
If there a solder bridge remove it with some braid and re-apply a bit of solder to each joint
8. Clean up
Clean the area with Q-tips and alcohol
Strictly speaking the ChipQuick flux is safe to leave behind, but I don't like the way it looks. Without washing the board, it can't be completely removed though.
Place the socket bottom you previously cut out in side the socket. Just let it sit there, don't glue it or anything. This will serve to prevent the PROM from bottoming out, which can cause twisting and connection problems
9. Insert the PROM and cross your fingers.
Push the PROM down until it bottoms out. With the box still open on the bench plug in the power supply. If the fan starts spinning within 10 seconds you are almost certainly OK. If not, get out volt meter and start checking for shorts or missed connections.
10. Reinstall the drive & battery, close it up and connect to a TV. See if it boots.
In the photos below (as attachments) the first is a socket with new PROM in a S3. Notice how close the socket must come to a nearby capacitor.
The second is a detail in the same S3 of the pin soldering. Notice a little flux I couldn't quite clean in the corners and between some pins. Since the spacing on the pins is about the same as the thickness of mechanical pencil lead, getting the exact amount of solder on the pads is crucial. Too much solder and a bridge is almost inevitable.
Still too scared to DIY? There may be people offering to do this service for you: