[BBC-Micro] Batteries in a Master

[Richard Gellman]

> Mine has a 3-AA caddy which contained some very old coppertops, different
> and highly attractive they were, in a perverse way. They're now history
> however. I can't detect a diode in the circuit anywhere though - but I

Mine has a diode and a resistor in series. The resistor I can sort of see
for voltage adjustment.. but the diode does baffle me slightly... unless
its some sort of "back-EMF" protection.

> a scary warning sticker - 'do not replace batteries - replace the entire
> unit with a new one from acorn'. Is this just arse-covering or is there a
> good reason for this?

Arse-covering.

When my battery pack died, I just desoldered the wires/resistor/diode from
the three batteries, and assembled them into a new pack made of 3
duracells. Works absolutely fine.

I think the fear was (as always) that the inexperienced might make a pig's
ear of replacing the batteries themselves and end up with an interesting
polarity problem, thus destroying several bits and pieces, most likely the
CMOS chip...

-- Richard