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Engineering: Maintenance & Repair



spare parts

. - Every week a new world!

Replacing the battery of NSM (NVRAM)
NSM devices from year 1984 to control technology 95 E


A common phenomenon is the error code ECb at the aforementioned devices. The manual says here about the 'Replace control unit' only. This is not necessary. The cause is a dead battery on the motherboard. This, however, hides in a RAM module (called NVRAM or Timekeeper). The chip carries the exact name MK48T12B-25th Such a chip can of course buy more. Cost is about 20-30 euros (we can arrange)


Remove the control unit, of course, make the device before the device! Just like lying down on the photo, make the chip find (may be obscured by a sticker) and soldering iron heat up.

Variation 1: Chip desolder and replace with equivalent.

Cheaper and just as effective is the following variation:
Take a Dremel or similar device with the following tools:

(3mm router for wood, plastic and light metals)

You put the control board, as shown in the figure, as to the fact that the label of the block is readable. Place the router in the middle and carefully move to the right. The left is the quartz, which must not be destroyed.

In the picture above clearly see the halfway exposed battery. Caution on the right are the two connection pins. This should be preserved if possible (!), So there later, the new battery can be soldered. So grope very carefully!

The upper pin is '+', the shorter lower pin is '-'. If necessary, this should be checked before removing the battery again!

So the whole situation with a new battery. Data: The original battery from the chip is a 3V lithium battery. The exact identification unfortunately I could not see. It works but any conventional 3V lithium button cell. (There's also in our shop!)

So, that was the work, now comes the test of patience ...

Initialize and rest Troubleshooting

The unit will display after turning on the error E C. For this purpose, there is a wonderful description on the sides of the machines magazine. See in the box 'topics Links to other websites / documents'.
's why I save myself the work. If a read or a service adapter keyboard are needed (which is not always necessary for troubleshooting), so we can offer the following assistance:

-> Description NSM Service Program
-> Service keypad borrow
-> reset adapter

Topics Links to other websites / documents

Error code EC after battery change NSM (->
Alternative Description Battery Replacement 'ICRaspeln' (-> ) Another description by E Cb, battery change (->

Important Notes

We give this advice to the best of my knowledge. Use of the information is entirely at your own risk. Also, neither the automatic archive-makers nor the authors for damages of any kind arising due to repair attempts, be held liable

Please note when working on the machine that repairs must be performed on energized parts by specialists. Unplug the appliance before opening the electric plug and touch when switched on any live parts.

© 2000-2003 by D.Breitenbach. The visual material is protected by copyright, a reproduction is only allowed with permission of the authors.