The Service Source Manual, which is geared to Apple's pluck-'n'-chuck methodology for AASP's use, will tell you little about circuitry or operation of the PB, although it does contain the functional specifications. You will learn more by opening and eyeballing the innards, given that you have the requisite Torx-10 and -8 drivers, and take the precaution of keeping yourself grounded continually as you explore. The case-securing screws are accessible from underneath (T10) and in the rear panel (T8). You need to crack the case (the system battery should already be out) at the rear seam, and to disengage the ribbon cable that connects the video signals from daughter card to the top case and display before parting the halves completely. You will have to get one finger, at least, inside the case through a narrow opening and around the metal ports and shaped plastic. The case halves must also be winkled carefully apart at the front. It is a painful process until you master it.
There is an MLB below a daughter-card with CPU, and perhaps above that a RAM-expansion card of 2-10MB. A base 4MB of RAM is soldered-in. An inverter board and interconnect board (mic., speaker and backup battery, and perhaps also an attached modem board) feed the display HT and video flexboard up to the display through its hinges. If you do nothing but look, remove dust, reseat the daughter card and RAM card and FDD and HDD flexboards, and look for and deal with corrosion on the MLB that may have come from a prior battery leakage, you will know that the connections are good.
The backup battery on the interconnect board is rugged, as well as being soldered-in. One of my 160s had not been in use for about a dozen years, but the backup batt. revived, and is still happy four years later. The catch is that BBs do not begin to recharge (they are only 30-50mAh capacity, compared with the system battery's 1000-odd mAh) before the NiCd system battery reaches near-full terminal voltage, not full charge, or about 7V. If you trawl these forums using 'backup battery' you will get more info. As long as the system battery is not too shot (say, 6.3V and up), the backup can recover in another 24hr or so with the PB on the AC adapter.
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] ]'> and it boots fine with only one dead pixel on the screen. The main battery is stone dead, and I presume the PRAM battery is as well, because the time displayed in the title bar changes randomly.
