reverse-engineering power

From: jpero_at_mail.cgo.wave.ca <(jpero_at_mail.cgo.wave.ca)>
Date: Sat May 16 16:43:31 1998

Guys and Doug,

Did it have the battery at all?

Often, I use this charging voltages to make a guess at operating
voltage for missing power bricks and that capacitors. That diode
could do one of two purposes: one might be for backward polarity by
shorting and blow a fuse might be worse or as a mild voltage drop
plus backward polarity protection. That capacitor serves to give you
the voltage limit by that WV number minus about 20% WV
printed on that cap.

And that cap could be a clue but we need to be double sure that both
legs of that cap is hooked directly to that power jack or one side is
via that diode that you ID'ed.

Try:

first: hook up the voltmeter to the 74xxxx chip for 5v and ground.

second: hook up that power jack with right size coaxial plug and to
veriable regulated power supply at least 600mA limited
third: start at 6V and chank up in 1V steps until it starts to work
properly especially for the display's crisp startup lamps.

Very common voltages due to the batteries:

8V (for 6V battery), 9V for 7.2V battery, 12V for 9V battery, so on
until about _at_12V max.

These voltages are used for rapid charging voltages.

Jason D.
email: jpero_at_cgo.wave.ca
Pero, Jason D.
Received on Sat May 16 1998 - 16:43:31 BST