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How to Repair a BP6 Battery Pack

This photoseries decribes the successful restauration of a damaged BP6 battery pack. Text pictures are provided by Pierre Leon.

STEP 1

Texas Instruments SR-51 II in need of resucitation.

STEP 2

Open up the BP6 battery housing and note the 3-wire connection to the calculator.

Unlike the BP7+ series, voltage regulation is done offboard from the battery pack.

STEP 3

Note the plug orientation in the housing.

 

STEP 4

Carefully disconnect the plug.  Mine had corrsosion deposits on it so handle with care.

 

STEP 5

Unless you are unlucky, there will be no need to remake the plug, but be sure to note how the plug is relocated in the housing.

 

STEP 6

Split the shell open using a craft knife. The PCB locates in one way but note the charging pins should you decide to attach the charger without using the locating guide of the case.

STEP 7

Remove the old batteries.  Handle with care.  The corrosion has engulfed the little PCB as well. TOXIC ! 

 

STEP 8

This is the two AA cell arrangement in the shell.  Your replacement batteries should be NiCd-type rated at 450-800mAh.

 

STEP 9

Clean up the small PCB.  Be careful to note the battery polarity and connection positions on the PCB.

 

STEP 10

Create your own two-cell pack if not available. Be careful when soldering onto the battery terminals. Don't let the batteries get hot. The ends will need to be scuffed with some emery paper before soldering. 

STEP 11

The old insulation between the battery posts and the PCB was discarded (a horrible bit of foam rubber) and replaced with a strip of plastic.

 

STEP 12

The battery assembly just fits the shell, but the paper clip bridge work meant a small cut out was required in each case half.

 

STEP 13

Re-assemble the shell halves and glue.  Then reconnect the calculator lead (watch the polarity).

 

STEP 14

Finally after 7 hours charging, the old machine is back to life again!

IT WORKS !

Pierre, Thanks!
Next time take the right numbers. It is simply SRQ(8).


Fineprint: This information was compiled carefully but we are not responsible if someone destroys his calculator or himself.

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If you have additions to the above article please email: pierreleon4@yahoo.co.uk, joerg@datamath.org.

Pierre Leon and Joerg Woerner, July 5, 2002. No reprints without written permission.