All Photos posted in the gallery above, but modification notes of the key stages below.
Opening the iPod, Storage Mod with iFlash
Opening the iPod and replacing the hard drive with the iFlash storage mode was straight forward. The major thing to take care of is:-
1) When removing the build in battery, be careful not to break the legs of the battery clip. Even though it still holds the battery ribbon cable if a leg is broken, its going to be harder to re-attach the battery
2) Be careful with the ribbon zif cable
3) The top of the iFlash card aligns with a notch on the side of the case. Make sure that it sits properly before assembling the case.
Preparing the Bluetooth Module
Finding the right Bluetooth module is painful. BT5.0 audio transmitters are hard to find, and most are transceivers at a much higher cost. I settled for a BT 4.2 Transceiver board but I had it locked permanently to transmit mode. The main selection criteria was that it was low power and can handle input voltage of 3.3V – 5V. I could also easily remove the audio connectors to get a large enough solder pad to connect to the iPod Audio lines. Once the components are removed, I tested the layout on the iPod to ensure that things can fit. The original idea was to be able to power the BT module using the iPod power lines itself which delivers 3.6V. I also included a small switch to allow me to totally power off the module when not in use.
Preparing the Power and Audio lines
Using a fine tip solder, solder the audio and power lines neatly and extend them out under the iFlash board. Take note that the board may have metal surfaces. I isolated them all with electric tape to ensure no short circuits can occur. Solder the power lines through the switch and audio to the LR of the bluetooth module. I also got a 1000mAh battery to replace the original 650mAh battery.
Audio Testing… Problems!
I reassembled the iPod but did not close the iPod. Tested the audio with BT speakers and verified that the circuit worked. However, on closer listening there was ground noise that leaked from the iPod to the BT module. This seems that this is because the power and the audio shares the same ground. As I usually make use of IEMs, this was unacceptable as it was really irritating and really distorted soft music. Partially closing the iPod also made me realise that the metal backing caused the range of the BT to be severely limited… to about 3m. This was also unacceptable to me.
Plastic Rear Panel
I ordered a new thick casing to accommodate the increased thickness due to components and proceeded to cut out a huge plate form the new back. I then laser cut 2 pieces of acrylic 2mm thick, (1 for spare!) to sit in the same space. This also allowed me to customise the markings on the rear panel. The aim really, is to address the BT range issue. Test assemblies looks great!
Power isolation to Remove Noise
I did several variations of trying to isolate noise between the power and audio. However, due to the shared ground, I was unable to do so with my limited knowledge. I tried RC circuits, LC circuits and power isolators. While all worked to some extend, the moment the audio ground touches the BT board, the noise is re-introduced. Isolating the ground also caused audio to cut out as the ground reference was changed. The final solution was to totally isolate the power supply to the BT by using a separate battery. This introduces another problem of having to find space for another battery and how to include a charging circuit for it. This effectively adds 2 more items to be inserted into the iPod. A battery and a Li-ion charging board.
I dug up a old Li-Ion charge regulator and connected it under the screen. I also identified a location on the side of the iPod so as to expose the micro USB port. Soldered everything in for a test with a separate battery, charging circuit, and the audio noise is gone! The charging circuit also works well.
Care must be taken when trying to dremel-cut a slot for the microUSB port. The metal structure around the iPod is fragile. Be sure to hold it tight when cutting. I did snap mine, but you can still use it even if its broken.
Battery Size Issues
Test fitting everything into the iPod with the thick iPod back case and acrylic back didn’t fit. Investigation concludes that the original 270mAh battery used was 6mm tall and couldn’t fit under the case of the iPod. The solution to this was to find a thinner battery. I finally decided on one that is 3mm thick but was only rated at 250mAh. This ultimately worked and I managed to fit everything into the iPod.
Advantages of this Modification
The clear advantage of doing this mod is that the iPod is now BT. But I have found that separating the power using another battery means that the iPod still is able to last for about 10-12 hours. The battery for BT is able to last for about 5 hours. The BT charge time is about 1/2 hour as the Li-Ion charger board charges at 500mAh. Upon testing, it seems that the iPod only charges at 250mAh. So it takes 4 hours to fully charge. All in all, charging for 1/2 hour for 5 hours seems pretty reasonable.
The microUSB slot at the side makes it really easy now to open the iPod for repairs. No more hard prying.
Quirks of this Modification
The BT board that I am using automatically goes into discovery mode at every startup. So devices have to be repaired every time. Its not a big deal, but just makes it a little inconvenient if you are picky.
The headphone and hold switch assembly for the slim iPod also seems to be just very slightly different to that of the thick iPod. While it also works, but you would have to adjust it slightly to make it fit well.
The mini switch I am using was old. Pressing too hard on the switch can cause the BT circuit to disconnect. I’d have to change the switch at some point to something of better quality, but it’ll have to do for now.
Edit – 20200702
The switch is now replaced with one that is angled to the side. This makes the switch structure a little stronger and no longer disconnect on slight touches. Also re-ran the power cables under the Flash board. Requires some re-solder, but electric tape is still required on the charging board to isolate it properly. Audio wire is also shortened and re-soldered neatly to the side.
I finished the mod by polishing the acrylic parts as well as the metal housing with Autosol and made a leather case for it. Once nicely polished, the iPod is a fingerprint magnet, but its lightweight, wireless playback connectivity, continued availability of a headphone audio out is a joy to use.
BT sound quality was pretty good but I might choose to upgrade it to one that is BT5.0 in the future if the price is right. The range of BT transmission is about 5m. Carrying the iPod in my backpack and using my IEMs wouldn’t be a problem.
This project took me a few months, with all the waiting for shipping.. but it was definitely a worthy project and I’m very happy with the results!