[Pro2006] Re: Pro 2006 low battery indicator always on

Fri, 11 Jul 2003 16:05:35 -0000

IC9 is the 5 volt regulator for the CPU. It has no effect on the low battery
circuit.  Q33 is the primary voltage regulator that reduces the 13.8 volt
input power to 9.2 volts.  Q33 voltages when plugged in and operating should
be:

10.6 v  right pin  (base, controlled by Zener diode D57)
13.8 v  center pin (collector, from power supplies)
  9.2 v  left pin  (emitter, to D56, D59, and IC9)

This pin layout may not match with yours, due to repairs or part
substitutions in production.

The 9 v backup battery is sensed by op-amp IC5.  When the battery voltage is
ok the op-amp output is 0 v to the CPU (IC501, pin 31).  Check the voltages
around IC5:

2.3 v  pin 10 (reference)
4.5 v  pin 9   (from voltage divider to 9 v battery)
0 v     pin 8   (to CPU through connector CN3 pin 11)

If you just want to kill the beep, unsolder or cut one end of C219.

----- Original Message ----- 
From: "Les Vaughn" <[email protected]>
To: <[email protected]>
Sent: 2003/07/11 03:35
Subject: [Pro2006] Re: Pro 2006 low battery indicator always on

> Thanks all for the input so far.
> I measured the voltage at the pads where the battery
> leads connect and it's fine.
> Looking on to Q33 which I suspect is the regulator
> someone mentioned, I have the following voltages (ref
> to ground) at pins 1, 2, 3 (assuming pin 1 is on the
> right as looking at the flat side):
>
> 9.2v    right pin
> 9.2v    center pin
> 8.74v   left pin
>
> This is with the unit unplugged and a fresh battery
> installed.
> I do have the service manual, if I could find the darn
> thing.  We moved recently and still don't have
> everything unpacked.
> I have all 3 of the Cheek books too, a quick skim
> through them didn't enlighten me on this situation,
> I'll try a more in-depth read this weekend.
> I got the books and service manual years ago with
> intentions of doing some of the mods but never did.
> I did do a memory expansion on a freinds 2020 though.
> Pretty cool.
> Les
>
>
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