Memory back up batteries

[Rob Flinn]

I have an XRI systems XR330 mtc smpte code unit.

It has a small green Varta memory back up battery, which I think is the type that gets charges up in circuit. The only markings it has on it are "Varta 044". It looks like the battery has 2 cells, & it has 3 PCB pins to solder it in place.

It needs replacing & I`m trying to work out which one to replace it, but the catalogues I have seem to have different code numbers, so I`m not sure what voltage, mAh I need.

From its dimensions the replacements seem to indicate that it is 2.4v @ 8mAh. Does this seem reasonable ?? Or does anyone have a code that would indicate that this would be the case ?

 

[Steve Jones]

haven't heard of that model battery, but the first thing to do is to look at the layout of the diodes around it to see if it is a non rechargeable lithium battery, or a rechargable NiCd. If there is a diode that prevents the 5 volt rail feeding back into the battery then it is not rechargeable, otherwise get your meter out and see if the circuit is trying to charge the battery, because putting a lithiun in there will cause fireworks. There will also be a diode in there that prevents the backup battery from trying to power the whole machine when the mains is turned off.

 

[Rob Flinn]

In the manual it says:

The internal batteries are continually recharged during use so that the settings should never be lost as long as the XR300 is in regular use.

From this I presume it is a rechargeable NiCd ?

 

[mcs]

[quote author="Rob Flinn"]From this I presume it is a rechargeable NiCd ?[/quote]
Or it could be NiMH - many of the sizes are available in both types...

But if it has no marking, it's probably NiCd. Look through the RS and Farnell catalogue, to find a battery that has the same size/pinout. That will probably work.

Best regards,

Mikkel C. Simonsen

 

[Rob Flinn]

Thanks Mikkel

I already looked in RS & the only one that looks to be the same size is 2.4v 80mAh. Is 2.4v likely to be enough to hold memory ?

 

[mcs]

[quote author="Rob Flinn"]Is 2.4v likely to be enough to hold memory ?[/quote]
Depends on what memory chips are used... Some memory chips need 2V, others 3V and some 5V - there isn't really a standard voltage.

Best regards,

Mikkel C. Simonsen

 

[Rob Flinn]

Thanks Mikkel,

looks like I`m just going to have to make an educated guess.

 

[tony dB]

a question about replacing.
Is it possible to swap standard backup batteries with the gear switched on?
I mean like in a synth module, when memory is powered by the mains will replacing the battery erase the adjusted presets?
this way i would avoid backing up some gear what seems complicated to get backed up. Never tried it myself though..

Tony