Soldered Button Cell Battery?

[MRC01]

My Tascam DA3000 doesn't remember the date/time clock setting, not even when powered on. The problem is that uses a button cell battery for this, and the battery is dead. This battery is a small button cell soldered to the bottom of the central PCB. I expected to find a slide-in button cell slot like in a quartz watch or PC motherboard, but no, it's a button cell with tabs, soldered in. What a PITA <sigh>

And of course, they had to put it on the bottom of the PCB, so you must remove more than 10 tiny connectors, a mix of cable & ribbon, to remove the board entirely, in order to desolder the old and solder the new one in. Since these button cells aren't rechargeable and don't last more than about 3 years, it seems to be poor design for an otherwise great piece of gear. Yeah I'm just griping about it.

Fortunately, it's merely an annoyance. the DA3000 works fine without the clock.

 

[MRC01]

I'm thinking I should improve this when I replace the battery. Solder a couple of wires connecting the + and - contact points on bottom of the board, to a button cell battery cage that I can tape or velcro to an accessible spot inside the chassis (there's plenty of room). Then subsequent battery swaps could be done in 10 minutes without any soldering.

 

[DonH56]

I'm thinking I should improve this when I replace the battery. Solder a couple of wires connecting the + and - contact points on bottom of the board, to a button cell battery cage that I can tape or velcro to an accessible spot inside the chassis (there's plenty of room). Then subsequent battery swaps could be done in 10 minutes without any soldering.

A lot of PCs had the same issue (and perhaps still do; I don't know). I used to have a small stock of leaded button-cell holders and would do exactly that -- connect the leads to the board and mount (sometimes just hot glue) the holder at a convenient place.

 

[MRC01]

Here's the fix. While I was at it, I used a CR2032 instead of the OEM MS614SE - same voltage, but easier to get and higher capacity.

PS: total cost: $1.25 for the battery cage. This recorder is pro gear and costs $1 k and up on the used market.
Surely, Tascam could have built it this way at the factory!

 

[antcollinet]

Here's the fix. While I was at it, I used a CR2032 instead of the OEM MS614SE - same voltage, but easier to get and higher capacity.
View attachment 302521

PS: total cost: $1.25 for the battery cage. This recorder is pro gear and costs $1 k and up on the used market.
Surely, Tascam could have built it this way at the factory!

What, and miss out on service business.

Stuff like this drives future buying choices. Manufacturers should take note. Unacceptable to put a "wear out" part in such an inaccessible location.

 

[MRC01]

But wait, there's more! Tascam service replies:

I'm sorry the battery for this model was discontinued with no replacement.

Funny thing, the battery is a Seiko MS614SE with tabs, which is a stock part that you can buy anywhere. What they're really saying is they no longer "repair" DA3000 units when the battery dies and the date/time clock stops working.

I hope this thread helps other DA3000 owners. The modification is tedious with all those tiny little connectors and the soldering needs a fine tip. But it's not too hard, and it's a one-and-done mod.

 

[AnalogSteph]

MS614SE is, in fact, a rechargeable button cell (3 V, 3.4 mAh). I was already wondering why they would be soldering in a primary cell.

You should probably swap out the CR2032 for an ML2032 rechargeable. Plan B, solder in a Schottky diode to keep the cell from being charged. Unless it just doesn't do anything to lithium primaries (it's not recommended for alkalines, for example).

 

[MRC01]

MS614SE is, in fact, a rechargeable button cell (3 V, 3.4 mAh). I was already wondering why they would be soldering in a one-way cell.

You should probably swap out the CR2032 for an ML2032 rechargeable. Plan B, solder in a Schottky diode to keep the cell from being charged.

Wow, I assumed it wasn't rechargeable because it was dead despite being plugged in. I guess it had too many charge/recharge cycles and died. Thanks for the tip. I wouldn't want it to blow up that CR2032 battery trying to charge it.

 

[antcollinet]

I hope this thread helps other DA3000 owners. ..

Should also help other potential Tascam customers make an informed choice.

 

[solderdude]

MS614SE is, in fact, a rechargeable button cell (3 V, 3.4 mAh). I was already wondering why they would be soldering in a primary cell.

Plan B, solder in a Schottky diode to keep the cell from being charged. Unless it just doesn't do anything to lithium primaries (it's not recommended for alkalines, for example).

There is a snag here. We don't know how the cell was charged. Maybe from 5V via a simple resistor, maybe from 3.3V or a bit higher.
The battery itself may have doubled as a zener diode in this case.
It is possible that when using a schottky diode the actual voltage fed to the memory circuit pin could become too high.
Maybe it isn't an issue at all though and the backup voltage pin can handle a higher than expected voltage easily in which case the Shottky diode is a great idea.
It will cut draw from the battery when on and will prevent the battery from receiving a charging current. I have no idea how high that current is and if that is a problem for the battery.

Probably your plan A would be best.

Plan C could be a gold-cap (with zener in parallel if needed ?) but would probably go for your plan A (rechargeable 2032)

 

[MRC01]

There is a snag here. We don't know how the cell was charged. Maybe from 5V via a simple resistor, maybe from 3.3V or a bit higher.
...
Probably your plan A would be best.
...
Plan C could be a gold-cap (with zener in parallel if needed ?) but would probably go for your plan A (rechargeable 2032)

I went with Plan A. I pulled the CR2032 last night (which wasn't warmer than room temperature, didn't seem to be damaged) and will install the ML2032 today. Good thing it's so easy to swap batteries now...

 

[gene_stl]

And also remember that it is usually difficult or impossible to solder to most coin cell type batteries. If they are rechargeable they often have stainless steel conductors spot welded to the cases. This can be improvised but Batteries Plus can do it for you and they are pretty experienced at it especially if you tell them exactly what you want. You can bring them the extracted board and often if they have time they will do it while you wait and stupidvise.

 

[MRC01]

And also remember that it is usually difficult or impossible to solder to most coin cell type batteries. ...

I take that further and don't solder on batteries of any kind. First, it's hard to get solder to stick to a battery terminal, and second, it doesn't seem safe to apply that heat to a battery. If I need that, I get batteries that have tabs already attached, then solder to the tabs.

 

[gene_stl]

The point about soldering heat is well taken. Although I have managed to solder to them and the heat did not seem to cause a problem. You have to rough the surface with a moto tool and solder immediately before the oxide layer can get too thick and use an active flux. Spot welding heats up the battery less and is suitable for field repairs.

Spot welders for orthodontics used to be available and could be used on batteries. I also once had to make platinum electrodes on an ancient job and it is even harder to solder to than stainless steel. I borrowed an orthodontic spot welder from the dental school who had ten of them and let me have one long term.

orthodontic spot welder - Google Search