Re: 1502/1503 Charging Discrepancy

Dave Casey

What R and C did you use for the emulator? I built one awhile back but it
doesn't seem to be doing the trick (and I can't remember if it ever did).
TekWiki suggests 200 to 270 ohms, 10W, in parallel with 2200uF. I need to
open mine up and see what I put in there and whether or not the caps are
still good.

Dave Casey

On Fri, Sep 27, 2019 at 12:34 PM fiftythreebuick <ae5i@...> wrote:

Hi Dave-

I got tired of nursing those doggone nicads and since I use my 1502 and
1503 mostly where AC is available, I pulled the battery pack and built an
emulator to go in its place. Now the TDR always thinks it has a perfect
battery in place and always works, without having to be so careful about
the batteries. If I need battery operation, it's as simple as swapping the
emulator out for a battery pack.

I really wish they had not designed it so that it won't run without those
batteries... Same with the 323. Having to manage the batteries is an
aggravation if you don't need them very often.


On Thu, Sep 26, 2019 at 09:47 PM, Dave Casey wrote:

I was dusting off my TDR and charging up the battery pack I rebuilt a few
years back when I noticed something interesting. In the 1982 revisions of
both the 1502 and 1503 manuals, it clearly states that the battery will
be overcharged if the unit is left plugged in past the maximum 16 hour
recharge time. In the 1989 revision of the 1502 manual, it states exactly
the opposite. The A6 power supply board didn't change between those
revisions. The Theory of Operation sections regarding the battery charger
have changed between the different revisions, but only in phrasing. The
content remains the same, offering no explanation as to what does or does
not overcharge the battery.

Presumably the later information is the better information, but does
know the story behind why it changed?

Dave Casey

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