Fixing the F2A with GBA SP Problem

by Tony Cool (loosely translated from the original Spanish version and editorialised by Pat Crowe)

Many people have had compatibility problems when using the Parallel Port version of the F2A cable with the Gameboy Advance SP. The cable was designed before the availability of the SP version of the Advance and was not able to predict a slight design change in the link port. For most people this results in unreliable operation. Tony's pictures illustrate a possible symptom. The most serious effect is that the cartridge cannot be programmed correctly.

[Editor's Note: The problem lies in a derived 3.3V supply, used to power part of the circuit. It is generated by a switching waveform, which produced a smooth dc 3.3V on the GBA. On the SP a triangular waveform can be observed at this point, which can be smoothed by the addition of a suitable reservoir capacitor.]

 

This may result in errors when using the ROM image, or a totally blank screen.

It has been mentioned in the forums that 3 possible solutions for this problem exist.

Certainly the cheapest solution is to modify the parallel F2A cable. For anyone with basic soldering capabilities, the modification is simple, and even these days the part required is easy to obtain from any electronic component supplier. This article explains, step by step, how to make this modification.

 

Warning: In this explanation it is assumed that you have a basic knowledge of electronics, and know how to handle a soldering iron and solder. The soldering iron is not a toy, is a tool to melt solder and is VERY HOT. NONE OF THE AUTHORS OF THIS PAGE CAN BE HELD RESPONSIBLE FOR ANY POSSIBLE DAMAGE TO YOUR CABLE OR YOUR PERSON.  IF YOU DO NOT HAVE ELECTRONICS KNOWLEDGE, TALK TO SOMEONE WHO KNOWS WHAT THEY'RE DOING, AND IF YOU ARE A CHILD, GET HELP FROM A RESPONSIBLE ADULT.

THIS MODIFICATION IS AT YOUR OWN RISK.

 

Necessary Materials:

The materials to make the modification are shown here:

  1. F2A Cable to be modified. We presumably already have this.
  2. Soldering iron. You need one with a fine tip, designed for electronics work.
  3. A flat bladed screwdriver, to help to open the housing
  4. A tool with a fine end. Possibly a modeling knife.
  5. Solder. Electronics solder with its own flux. You will only need a few centimeters.
  6. Capacitor
  7. [Editors Note: Personally I would have also mentioned a pair of fine tipped cutters, for snipping the wire, and fine pointed pliers to bend the wires. These are my 2 most important electronics tools]

This capacitor is the key component, since it is the part we are going to add the the circuit to perform the modification. There are many different types of capacitor. In this case we used an electrolytic capacitor of 100V, 2.2uF (100 volts, 2.2 microfarads) like the one of the photo:

You need to know that you can get polarised and non-polarised capacitors. A polarised capacitor (also know as an electrolytic capacitor) has a positive (+) and a negative (-) end, and must be connected the right way round. Non-polarised capacitors may be connected either way. For our current purposes we use an electrolytic capacitor because they are physically smaller for a given capacitance value. The capacitor should not cost more than a few pence (cents, whatever).

[Editor's Note: the value is not too critical. Choose at least 1uF and at least 6V. The actual voltage across the capacitor will be 3.3V. Don't choose a much larger value unless it is physically small enough to fit.]

Steps to follow:

  1. Raise the 4 tabs that lock the two halves of the housing together. Take extreme care as the plastic is very brittle. Use you fine tipped tool to do this. [Editor's note: Even expecting trouble I broke off two of my tabs doing this, so be really careful]

  1. While doing this (!), ease the two halves of the housing apart, using the flat blade screwdriver. Remember you're still being careful not to break those tabs!

  1. Once you have it open, carefully put aside the 2 screws and the housing halves.

  1. Turn over the printed circuit board (pcb) and locate the points where we need to solder on the capacitor. Be very careful to identify the correct points shown in the photo, particularly the left-hand one.


    Click here for a close-up of these soldering points

  1. Apply a little solder to the first point (this is called tinning). Be really careful that the solder does not blob across to any adjacent point of solder, as this will stop your cable working and may permanently damage it.

  1. Repeat for the second soldering point. This is one of the pins on the parallel port connector. The pins are very close to each other so be careful not to bridge the gap to the next pin with solder.

  1. Prepare the wire ends of the capacitor (using cutters and pliers) so that:
  • the body lies flat against the pcb
  • the wire ends line up with the soldering points
  • the wires do not risk touching any other points in the circuit
  • the positive side of the capacitor (marked with a +) goes to the point marked + in the photo above

Check carefully before carrying on

Solder the positive (+) end to the board. [Editor's Note: good soldering practice would require that you apply solder at this point, because the flux helps to prevent 'dry' joints. Always check that the solder has 'wetted' (flowed onto) the pad and wire being soldered, or the joint will not be reliable]. Mind - the iron is hot.

  1. Repeat for the negative (-) connection.
  1. Finally after everything has cooled off, press the capacitor down with a finger to ensure it fits within the housing.

 

Now we've modified the unit we need to test it.

 

Connect cable to the parallel port of your computer. Don't close it yet in case it doesn't work.

  • Open the F2AWriter program, and before flashing a ROM, select the option "Config" and activate the Verify option.

Leave the window by clicking on OK

Having copied the ROM, the program makes a thorough verification check using a CRC.

The 'Checking' number depends on the size of the ROM in question. In the picture we copied a ROM of PogoShell of 31.98 Mbytes of size, so the number goes up to 1023. The important thing to us is the message "CRC check ok"

If when copying there is an error, don't panic. Just switch off and on and try again. If this problem persists, check the connections.

Finally the critical test. We switch on the console... and bingo! It works!

 

Once it works put the covers back

Don't forget to position the screws before closing the housing. You can't do it after. Press the housing halves gently till it clicks together. Check the cable is aligned correctly before closing.

If you were careful, the cable will look exactly the same as before, unless you look though the casing at the new capacitor.

 

Finished - Just like new!

 

Beats having to buying a USB cable!

 

 

And that's it. Shouldn't take more than 10 minutes if you know what you're doing. If you have any doubts, or aren't sure of something you may contact Tony.

[Thanks to Tony Cool for permission to reproduce the article]