Amiga Technical Resource - Replacing Cyberstorm mk3 socket

Replacing the 68060 socket on Cyberstorm mk3 CPU board

Introduction

The Cyberstorm mk3 made by Phase 5, and later by DCE, are among the fastest performing CPU boards made for the 68k "Classic" Amiga computer. There are several variants of this expansion board; with and without PPC (2nd processor), various PPC speeds, with either a 68040 or 68060 CPU.

An unfortunate fact with these boards is that hardware failures are common, often in the form of intermittent or open circuit solder joints. The main component affected is usually the 68040/68060 socket, which is soldered to the printed circuit board using BGA (Ball Grid Array) technology. With this type of device, the electrical contact and mechanical mounting is by using balls of solder on the contacts underneath the socket to connect to pads on the PCB. It would appear that due to thermal and mechanical stresses on these solder contacts, some of the joints eventually crack, which lead to problems such as the computer crashing/becoming unstable, or simply failing to boot.

This would appear to be one of the more common problems with the Cyberstorm mk3. Often a quick way to test to check for this particular fault is to:

Confirm computer will not boot - power on and repeatedly press Caps Lock, if the LED stops toggling after 15 or so presses, it means the CPU is not responding.
Apply firm downward pressure to the centre of the 68060 (avoid stressing the board by excess flexing).
Power on the computer, maintaining a constant firm pressure on the CPU.
Confirm the CPU is now active - power on and repeatedly press Caps Lock, the LED should keep toggling after 15 or so presses, or you can hold down both mouse buttons to check if the Early Boot Menu appears.

The method above is not a fool-proof way to detect solder joint problems, but it often gives an indication of the problem.

Disclaimer and caution
While the information on this page has been checked and is correct to the best of my knowledge, there is still the possibility of unintentional errors.
Please report any errors directly to this address so they can be corrected.

As with any repair work to delicate electronic equipment, you risk causing further damage to your system or yourself. I cannot be held responsible for any equipment damage or personal injury.

It is strongly advised that you possess some good common sense and preferably have previous experience in working with electronics before undertaking any repair on your system.
As always, you should take all anti-static precautions when working with semiconductor devices.

Parts and tools required

You'll require a standard array of hand soldering and SMD soldering tools as well as components to construct the replacement socket.
It's possible to use single in-line socket strips or individual pin sockets supplied on a carrier strip, as shown below. The 68060 has 223 socket pins locations, so you'll need to buy the correct number of socket strips to give you at least 223 pins, plus a few spare.


2.54mm SIL socket strip, element14 (formerly Farnell) part number 1218868	Socket pins on carrier strip, element14 (formerly Farnell) part number 177850

Precidip socket pins on 2.54mm carrier strip - part number 714-87-164-31-012 - click image for larger view

The Precidip socket pins will be used in this example, though the job is likely to be easier if the SIL (Single In-Line) socket strip shown in the top left photo above were to be used.

Socket replacement

It's generally not possible to fit a replacement BGA socket as this requires very specialised equipment to carry out the work and inspect the joints afterwards. This guide assumes you don't have access to a BGA placement/rework station and a x-ray inspection system.

With a great deal of care, and a high degree of soldering skill, it is possible to fit a replacement PGA (Pin Grid Array) socket, formed from easily available off the shelf components.

Important!

This procedure requires that you are extremely skilled in hand soldering, and that you have access to appropriate hand soldering (and SMD soldering) equipment.

Do not attempt this procedure unless you are fully competent in high accuracy soldering.

Once you have all the tools required and the correct number of socket pins, the first task is to remove the CPU from it's socket.

Don't forget you can click on these images for a larger version.
The correct tool to remove a Pin Grid Array device is one of these, but since most people will not have access to such tools, other methods are possible. One way is to use a small-medium sized flat blade screwdriver (approx. 5mm) and gently work around the circumference of the socket, inserting the blade in the small gap between the bottom of the CPU and the top of the socket and gently twisting the screwdriver.
Only a small amount of force should be used for each twist, else the CPU may be damaged. It is necessary to repeat 5-10 "rotations" to extract the CPU.
Note that the CPU is only accessible on three sides, as the CyberVision socket blocks one side of the CPU.
The socket is removed using hot air from a SMD rework machine. Before doing so, it's necessary to shield surrounding plastic parts; the SIMM sockets and CyberVision socket, from the hot air to prevent them from being damaged.
A simple but effective heat shield can be formed by folding a sheet of aluminium foil in half, then wrapping the double sheet of foil around the plastic items as shown below.
Fit a medium sized (5-8mm inside diameter) single tube nozzle to the hot air rework tool. Set the heat to medium and the air speed to medium.
Hold the hot air tool in your left hand (if you are right handed). Position tip of the tool's nozzle about 10cm above the socket and gently pre-heat the area for a few seconds, this reduces stress on the circuit board and surrounding components.
Now hold the tip of the nozzle about 2cm above the socket. Move the nozzle about in a circular pattern above the socket so the hot air evenly heats all of the solder joints.
Important! Never hold the nozzle in one spot when it's close to the PCB! Keep it moving all the time, otherwise the concentrated heat in one area can scorch the circuit board or cause it to blister.
The solder will begin to melt after about 60 seconds of heating. Gently apply a little upward pressure from under one side of the socket. It will lift very easily once the solder has melted. Do not force the socket; else the PCB pads will be damaged.
After one side has lifted, concentrate heat to other sides of the socket. Apply gentle upward pressure as before to lift the socket from the PCB.
Lift the socket clear and turn off the rework tool.
Clean all the old solder from the PCB pads using solder wick, then clean PCB surface with isopropyl alcohol or methylated spirits.
The pads must be free from solder lumps, and appear clean, shiny and smooth.
To aid soldering, apply some no-clean liquid flux to the pads. This is not essential for hand soldering wire as it will contain flux, though liquid flux helps a great deal with liquid solder paste if it is used.
Now for the trickier stuff. Begin from the row nearest the CyberVision socket and work outwards; cut the correct number of socket pin positions from the header strip. Carefully align the strip so that each socket sits in the centre of each solder pad and that the socket strip is aligned perfectly vertical. Failure to get this first row exactly right will cause the remaining new socket pins to be misaligned as well.
For the 68060 to be able to plugged into the new socket, each pin must be positioned vertically and perfectly in-line with the rest of the socket pins.

Hold the row level with one hand and apply solder to a single end pin only. It may help to use liquid solder paste as opposed to solder wire, to partially free the use of your hands. In the case of solder paste, apply a blob of paste to the base of one socket pin, and then heat it with the soldering iron.
After one pin is soldered, the row will then sit in place by itself. Use this opportunity to check that the row is still vertical and in-line with the PCB solder pads. To realign the strip, heat the solder and move the strip as required until it is perfect. Once it looks good, solder a pin at the opposite end of the row so one pin at each end of the row is now soldered. Check the strip alignment again, heating the solder joints and repositioning as required.
Once the alignment of the strip is perfect, solder all of the pins in the strip to the solder pads. If using individual socket pins as in this example, leave the carrier strip (the black plastic part) in place. Carefully check each of the solder joints, as they are not easily accessible once the socket has been built up.
Cut a length of socket strip to form the second row and position it on the PCB beside the first row. As before, align the pins to the centre of the PCB pads.
It's important to note that the width of the socket strip or carrier strip might be slightly thinner than 2.54mm; this needs to be checked carefully. In the case that the strip is thinner than 2.54mm, then each new socket row must be positioned further away from the previous socket accordingly, else if the new row is positioned against the previous row, the vertical alignment of each new row will gradually drift which will make the insertion of the 68060 CPU into the final socket very difficult.
In this case, the header strip is 2.3mm wide, therefore there needs to be a gap of (2.54 - 2.3mm = 0.24mm) between each carrier strip. A metal or plastic feeler gauge can be used to measure this gap.
Use the same process as before; solder one pin at each end of the row and very carefully check the alignment of the entire strip before soldering each of the socket pins.
Continue the process to fit the rest of the rows. The centre rows are simply formed using 2 x rows of 4 socket pins.
Once all the rows have been populated, the carrier strip can be removed. Simply pull it upwards clear of the pin sockets.
If socket strip has been used instead of pin sockets, there is nothing to remove.
Visually inspect the socket pins to check all of them have remained firmly soldered to the PCB. If one solder joint has been missed, it'll be very obvious as the pin will be removed along with the header strip.
If a solder joint has been missed, attach the unsoldered pin to a length of carrier strip and locate it using surrounding socket pins. Apply some liquid solder paste to the base of the unsoldered pin. Fit a 0.5mm or 1mm soldering iron needle tip which will reach down between the soldered socket pins to heat the solder paste. Take care not to heat neighbouring pins, else their solder joints will melt and ruin the pin alignment.

Note that if socket strip is used instead of pin sockets, a missing or bad solder joint will not be obvious as it'll be hidden under the plastic upper body of the socket, and neighbouring good solder joints will hold the contact with the bad joint in place, even though it may not be electrically connected. For this reason, it is very important to carefully check each solder joint on the socket strip as these were being populated.
The final task is to fit the 68060 CPU into the new socket. Check the orientation is correct as per the image below.
Unless each of the pin sockets has been aligned perfectly, the CPU may not easily fit into place. Do not force the CPU into the socket, as this will only result in bent/broken pins. A better approach is to gradually insert one side of the CPU first. As the CPU mates into the socket, it's possible to see which pins are causing the misalignment. Using small needle nose pliers, add a small degree of angle to the CPU pins. Do not attempt to bend any of the pin sockets as this will damage the PCB solder pad. If the alignment in one particular pin socket is bad, the solder should be heated using a needle soldering iron tip and the pin socket realigned accordingly.
Wiggling the CPU in a circular motion may help to correct any pins which have minor socket misalignments.
It's worth checking the motherboard clock source jumpers, located underneath the CPU board area of the motherboard. They should both be set correctly according to the manual before fitting the CPU board into the computer.
Fit the CPU board to the computer and power on the system. If everything is working correctly, then the computer should boot normally. Or you should be able to hold down both mouse buttons after power on to access the Early Boot Menu. If there are Software Failure messages during execution of the Startup-Sequence, then the incorrect 68060 system libraries may be installed. Copy the libraries contained within this archive to the system Libs: drawer.
If the computer does not boot as expected, repeatedly press the Caps Lock key approximately 15 times and check the LED always toggles. If the LED stops toggling, it means the CPU is not responding. Check memory SIMMs are correctly fitted to the Cyberstorm board as per the manual. Note that the A4000D motherboard needs a Chip Memory SIMM fitted in order to boot.
Check that none of the pins on the 68060 were bent during installation. Check for loose crystal oscillator modules on the Cyberstorm board, if they are socketed.
There may be other problems with the Cyberstorm board, unfortunately these can be difficult to trace as there is no service information for these boards available.

Try a known working CPU board in the computer to confirm if the problem is with the Cyberstorm board, or with the computer itself. Refer to the hardware reference pages for information on common problems.

Questions, comments, errors? Email me.