Here are the links to my schematic:
http://olympus.dementia.org/Hardware/PDFs/T45_Chrg_1_0.pdf
And Bruce's physical layout sketch.
http://olympus.dementia.org/Hardware/misc/T45_nicad.jpg
The reason your flash worked partly is that at least one of the strings of
cells, probably only has a single defective cell. This allows that invertor to
charge up the flash cap to a lower voltage where it can still be triggered
albeit with low light etc.
The cost to have the pack repaired is high because of tedious labour and large
number of cells. With care you can cut open the pack along the seams with a
dremel cut blade (best) or a fine point dremel diamond coated bit or even with
the tip of a fine soldering iron.
If you do, do it yourself you need to find a source of tabbed cells. You need
to replace all cells, as mixing old and new ones does not last long. My
favourite place to deal with is the NiCdLady in southern CA. If you ask nicely
they will usually do the tabs for free, even though they list a small fee for
tabbing. You still have to cut the tabs and solder the cells together and fit
it all in the small space. I would recommend you do not use NiMh cells as the
charger will damage them quickly.
An alternative to replacing the NiCd cells would be to use just two Hawker
Sealed Pb, D cells connected in series and hook them up to all the + terminals
in parallel. You would have to make some sort of adapter connector. Although a
pair of these D cells can fit inside the handle, you would have to figure out
how to hold them in. You would also have to make a voltage regulated charger
with a voltage of exactly 4.7V. So this is only an option if you have
electronics skills. One advantage is the hawker cells are about $6 ea ($12
tot), so a bit cheaper, although you will not get so many flashes out, You
could make 2 or three packs for the cost of a single set of NiCd's.
Beware of shorting the hawker cells they can deliver about 180A into a short
causing things to glow red hot.
Regards,
Tim Hughes
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