Aiwa AM-F65 Minidisc Recorder battery replacement

Yes, Minidisc is old technology nowadays (2010). It never did make it big outside of Japan, but for a while it was actually the ultimate in recordable portable audio. I still find Minidisc great for live recording and quick playback. Just pop a disc in and go, no need to worry about transferring back and forth to computer.

The Aiwa AM-F65 and its hard-to-find battery

One of the less common portable recorders is the Aiwa AM-F65 (the AM-F70 is the same machine with a backlit LCD). Unusually for a portable, it has a jog wheel which works as a near-analog volume control on playback, and is also used for selecting characters when titling. For me, that's a great bonus compared to repeatedly pressing up/+ and down/- buttons.

A downside however of this machine is the battery. Most portables use standard AA batteries which of course are readily available. The Aiwa on the other hand uses a Li-Ion battery, and this particular type was unfortunately only used in a couple of Aiwa models (the AM-F65, AM-F70 , AM-F72, AM-F75 and AM-F80) and JVC machines. It was difficult and expensive to obtain as a spare part when the machine was new (around 1999); today (2010) it's virtually impossible to find. Very few online stores list it; whether or not it is actually available is unknown; at any rate, the price is very high (over USD $100), which doesn't make it worth while for such an old machine.

With the original battery out of the question I thought that perhaps a battery originally intended for another device would fit, perhaps after some adaptation. Looking through on-line catalogues for various battery sites was downputting however: virtually all Li-Ion batteries of this capacity have either a flat geometry or cylindrical geometry which won't fit.

AM-F65 with battery
AM-F65 Minidisc Recorder
with original LIB-902 3.6V 700mAh battery

open AM-F65 with battery

Original battery in place (with back of recorder removed)

After searching for quite a while I came across a battery intended for a Sony PDA which looked promising. Designated LIS1259, it's the same width as the Aiwa battery at its widest point, slightly thinner, and quite a bit shorter. Unfortunately, it didn't have poles at each end like the Aiwa, instead, two wires eminated from one end.

Being the only battery whose measurements even came close to fitting inside the Aiwa recorder, I decided to give it a try. I figured I could solder the wires to the battery terminals inside the Aiwa which would actually give me another advantage: at times, a mild knock to the recorder would interrupt the connection to the battery potentially turning the machine off in the middle of a recording. So soldering the battery connections would actually be an advantage. The disadvantage of having to open the machine in order to replace the battery was one I could live with; the battery lasts for several years (I'd had the original battery in my recorder for 10 years).

Available as an aftermarket part in both 650mAh (appearantly the original capacity for the type) and 700mAH capacities, the LIS1259 is available from several on-line battery sites for a couple of tens of dollars. The difference in rated voltage (3.6V vs. 3.7V should be insignificant, or at the most reflect a minor difference in internal chemistry. I chose the larger capacity (700mAh) version as it had the same capacity as the original Aiwa battery.

LIB-902 and LIS1259 batteries
Aiwa LIB-902 (67.5 x 18/19 x 10.5 mm)
vs.
Aftermarket LIS1259 (44.5 x 19 x 9.5 mm)

Fitting the LIS1259

WARNING! This section describes connecting a live (albeit low voltage, but still high capacity) battery to a sensitive piece of electronic equipment. Do not attempt this unless you are comfortable with this. If you wreck your Minidisc recorder, or the battery blows up in your face, I will not be held responsible. If in doubt, let someone who knows what they are doing perform the operation.

You'll need a bit of ingenuity to fit the battery, and some soldering skills. This is a desciption of how I went about it, use it as a starting point, not as a step-by-step instruction.

What you need

Opening the case

First, remove the original battery. Put it in a safe place.

Removing screws

You only need to remove the back of the case (thankfully!). There are two screws along the top of the machine, four on the back (three at the top, and one in the middle), one on the side near the power supply input and one near the input/output sockets. All screws are the same except for the middle one.

Opened
Opened (note: rear case is wrong way round!)

Modifying the replacement battery

The Aiwa battery has an odd stepped shape. At one end, it is 19mm wide, at the other it is 18mm. Thanks to this, it is impossible to insert it wrong way around. The LIS1259 is 19mm wide, so it must be mounted slightly offset so that it doesn't intrude on the 18mm area where it won't fit (a bracket makes this area narrower). At the same time, I didn' t want to mount it so that it would risk being damaged by one of the two screws in the top of the case.

However, there is a quirk. At end where the wires eminate from the LIS1259, the battery is sligthly wider, seemingly due to an internal PCB inside. At my first attempt, I put the this end of the battery towards the inner part of the compartment, which resulted in the lid not closing properly. After turning the battery around, it fits, if only just.

The red (plus) wire from the battery needs to be extended in order to reach the positive terminal inside the machine. That's where the extra red wire and heat shrink tubing comes in. The white connector on the battery wires is to be removed.

Connecting the battery

Negative terminal
Positive terminal
The negative pole is located near the battery lid, slightly obscured by a bracket for one of the rear mounting screws. The PCB is marked BT- here. This is where the black (minus) wire from the battery is to be soldered. There is a small solder pad on the PCB which is can be used. The positive pole is located at the other end of the battery compartment. It is easier to reach and is marked BATT+. The red (plus) wire will be soldered here. Again, Aiwa have thankfully provided an unused solder pad on the PCB which can be used.

Mounting the battery

Battery in place
As mentioned above, the battery position is sligthly critical. It must be outside the "18mm area", as well as out of range of the two mounting screws along the top of the machine, to avoid the screws damaging the battery or its insulation.

Finally, there seems to be slightly more space at the the battery lid end, so it must be mounted with the slightly wider end where the wires eminate at that end.

The image on the left shows the battery in place in its intended position, also clearly showing the extended red wire and heat shrink tubing over the joint.

I opted to put the side where the wires eminate facing towards the top of the machine, as there was a serial number label there which I figured would offer additional insulation if the wires got damaged.

Battery in place
In order to secure the battery, I contemplated a couple of options. Glue could loosen and would make subsequent replacement difficult. I had similar concerns about double-sided tape. Stuffing foam rubber or similar beside the battery would potentially bend or at least stress the case. Finally I opted to add spacers at each end of the battery, so that the original battery terminal springs and battery door would hold the battery in place. As can be seen in the picture to the left, I used two small rubber feet at one end, and a stick of plastic at the other end. The material is not critical, but it mustn't be metal, or there would be the risk of a short circuit. The size is relatively critical: if the spacer is two short, the battery will be loose, if it is too long, the battery lid will be stressed.

Note: of course, the battery door could be glued shut as there is no need for it, but I wanted to have a fallback in case the new battery wouldn't fit and I had to resume using the old one.

Finally, tuck the wires nicely so that they won't be damaged when the rear of the case is remounted.

Putting it all together

Put the rear case on, and check that the top of the recorder closes properly. Again, be careful not to short-circuit the battery with the metal rear case, as the machine is live now, with the battery connected. Also check that the machine comes on when the lid is closed; you could even insert a disc and check that it plays. Li-Ion batteries are delivered partly charged, so there should be power enough to run the machine. The battery should also not be loose or tend to pop out when the cover is opened.

When remounting the rear case, make sure that the three grey switches line up with their counterparts on the PCB before screwing on the case. Don't tighten the screws too much, it will make them difficult to remove if needed later.

Charging and testing

After testing that the recorder operates and thus that the battery is properly connected, try charging using the Aiwa charger. The first time I charged the machine under supervision, just in case any differences in the battery types would cause it to heat up. I observed no ill effects, and after about an hour the battery was fully charged (it was already partly charged as delivered). Setting the machine to play mode rewarded me with the display on the right, the three battery bars being something I haven't experienced for quite a while, at least not for more than a couple of minutes.
Fully charged!

Obtaining a LIS1259 battery

I'm not endorsing any battery sites, but here is a list of links which I found during my search. (Note: there seems to be a very similar if not identical battery called LIS1296). I obtained my battery from Digital Power Pro, via their eBay store.

Digital Power Pro (link to LIS1259 page).

eBatts.com (link to LIS1259 page).

Kahlon (link to LIS 1259 page).

(Note that the exact measurements for the same battery vary between different web sites ...)


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