Master battery backup. By John Ilsley. This article is for Master128 users, and for one user who questioned Daniel about the Master128 battery backup. The official battery, doesn't last 5 minutes. It is also sometimes forgotten that the Master128 has the capability of charging its own battery. The Master128 only draws power from the battery during the times it is switched off when the timer chip, date and configuration settings are maintained. For this it draws very little current, but enough to send the batteries flat, especially if the computer is not used for a few days. There is however a simple way to cut buying your batteries by 1/8th or more. It involves a very simple alteration to your computer. Simply follow these instructions. Note: Neither 8BS, the editors or myself can be held responsible for anything that should go wrong should you not follow these instructions correctly. I suggest that you draw out how the battery is at present in case you wish to revert back to it or if you find something goes wrong. You will need the following tools: Soldering iron, solder, a couple of pieces of wire about two feet in all. I suggest you get one foot of red and one foot of black. 24swg will be fine. Please note, if this battery is not connected the correct way, it will destroy your configuration settings and if left in, will destroy the timer chip. Therefore you MUST follow these instructions carefully. This picture will also be very helpful: j################### + Note White h.l <,,,,,,, - diode end ]j#k IN4004 5 jpz diode 5 j 5 Don't use `zp 5 Ni-Cads j j 120ohm 5 j j resistor 5 "k# 5 j 5 + ~4 5 7##5 j#######! Battery 5 5 j 5 5 j - 5 5 j - # 7!<.,4 I am willing to + 7##55 5 make these up if 5 55 5 you can't But I Batteries 5 55 5 cannot accept 5 5upp5 responsability if - -l,% o% + you install them "#### badly or have the ^^^ wrong machine Stiff wire First, turn off your computer, remove the plug, get your coat and go out and buy three long life AA size 1.5v batteries, Duracell are the best for this, they have more Ummph!... One Diode type IN4004 One 120 om 1/4 watt resistor. (Brown Red Brown). Save your configuration: *SPOOL status *STATUS *SPOOL As you may lose your configuration settings Now, remove the case, do this in the normal way by removing the four fixing screws from underneath the computer, also removing any cartridges in it. Now check that the leads go from the battery to the left hand side of the circuit board on the edge about half way down with the positive wire (red) being in the center and the earth (black) being at either of the ends. If they are, then to continue should be ok. If you have access to a test meter then test for positive and negative or just follow the battery terminals down. Now you will have to be careful when doing this project as if the batteries get too hot and over heat they may explode in your face showering you in hot acid. I strongly suggest eye protection for this. Sounds silly, but better then losing your sight. Take each battery and sand the top and bottom down with sand paper. Then put a spot of solder on the top and bottom of each battery. Take two of the batteries and join the positive (+) end of one to the negative end (-) of the other. So you end up with one on top of the other. This can be done using wire or by a quick solder job. If it ever gets too hot, leave it for a while. When you have done that, find a piece of stiff wire, a leadout wire from a resistor or a diode or similar will do. Place a spot of solder on the ends, You may have to clean them first, then place it on the positive (+) end of the two batteries. Then connect the negative (-) end of the third battery to the other end of the wire. Tape the two batteries that are side by side together. Solder the 120ohm resistor to the positive (+) end of the third battery, take the diode and placing it with the white end AWAY from the batteries, solder it on to the other end of the resistor. Strip 2/3rds of a centimeter off the end of the black wire, twist and flux it with solder. Then solder it onto the negative (-) end of the battery. That is the end away from the diode. Strip 2/3rds cm from the end of the red wire, solder it to the end of the diode. If you have access to a testmeter, chect that the voltage is about 4.5v DC from the red and black wire. If not, then something is wrong. Go through it again. If it is ok, make sure the computer is off, insulate the resistor and diode from contact with either the batteries or the computer. Ensure that it won't all fall to bits. I found a resin glue works fine for this. Place the three batteries into the left hand side of the case down by the side of the keyboard, they should just fit. Strip the loose wire ends, flux them and then touch the metal case of the power unit with the tip of the soldering iron so to earth it. Now all you have to do is solder the positive (+) wire from the battery to the center of the three pins, then the negative (-) wire to the pin nearest the keyboard. Make final checks, make sure the wires are in the right place, no solder is on the computer or circuit etc.. Then turn the computer on. If your'e lucky you will get the original settings you had. If not you will get: ACORN THIS IS NOT A LAUNGAGE. If you get this, all you have to do now is reconfigure. If you get a wierd screen or nothing at all, switch off and recheck everything and try again. If you still don't get anything, DO NOT CONTINUE. Replace the battery as it was originally then try and turn it on. If you need any help, then give either Chris, Daniel or myself a call. John Ilsley 27N