[SPARCbook] Power problems

[Borgen_Gary]

Liam,

Matthias' idea is probably a good one.  However, since the battery voltage
is not that well regulated in the first place, you should be able to use
your existing Tadpole power supply directly.  Just wire in a matching
connector and away you go.

The Tadpole series uses multiple DC-DC converters to derive system voltages
and charge the battery.  I have personally fixed a DC-DC board in a SB3 (it
uses a separate board for power, where the SB3X series have the power
supplies integrated onto the main board).  It wasn't pretty.  Almost every
mosfet was blown along with an inductor and several DC-DC controller IC's.
Before I rebuilt it, it smelled like a cheap cigar when I plugged it in.
There are no fuses.

The mosfets for the DC-DC's are in SOIC8 packages - Siliconix 9410 and 9430
(or equal).  The DC-DC controller IC's are Linear Technology LT1148-X.X
(where X.X is 5.0, 3.3, or adjustable).  The coils are surface mount
Coiltronics CTX units.  Download the datasheets.  Measure the mosfets for
shorts (should be a fairly high/consistent impedance part to part).  If you
find a short replace the mosfet.  Measure the coils for opens (most probable
in your case).  If open, replace with an equivalent part.  If you find a
shorted mosfet, you should also replace the LT1148 associated with it as
well.

Good luck.
----- Original Message ----- 
From: "Matthias Granberry" <matthias at utdallas.edu>
To: "For owners of Tadpole/RDI's SPARCbook series of portable Sun-compatible
computer systems." <sparcbook at sunhelp.org>
Sent: Thursday, April 15, 2004 1:32 PM
Subject: Re: [SPARCbook] Power problems


> If you run a WELL-REGULATED 12v power supply to the battery
> connectors, you can run it from the battery DC simply keep the battery
> removed.  I don't know what to do about the nvram, though.  Good luck on
it.
>
> "Liam" <Liam1f at blueyonder.co.uk> writes:
>
> > Hi,
> >      I've got a problem with my SB3 TX  which I've made worse and don't
know
> > what to do next.
> >    The original problem was that it stopped working when the charger was
> > plugged in. It would / will charge the battery (which obviously runs
down
> > quickly) when plugged in and not being used, but would then only run on
the
> > battery with the charger still connected.
> >    I have tried an original Tadpole charger, a HP one and my own bodged
one
> > with no result. They all, however, work on my SB3, SB3XP, PowerLite and
> > PrecisionBook. (This might sound greedy, but I like the little beasts!
> > Something about unusuality!) The TX being the higher spec. of the lot,
I'm
> > disappointed that this is the one that gave up.
> >    On guesswork, I have checked voltages going to the battery terminals
with
> > the charger connected; to both the internal battery and the terminals of
the
> > external battery (even though I don't have one) and have 5v and 12v
(-ish) on
> > some terminals.
> >    Thinking myself clever by previously identifying damaged components
on one
> > of the boards of my XP, then finding out the values (straight from
Tadpole, no
> > less!) and finding someone to do an economical repair, I took the whole
thing
> > apart to examine the circuit board tracks. I am certainly no expert,
but
> > there was no burning damage evident anywhere. At one stage, though,
while
> > poking and pressing connections with the charger plugged in, I'm sure I
> > smelled burning. My wife says she didn't....but we don't always agree on
> > things (especially computer related), anyway.
> >    While I had the whole thing apart, (I can explain why I did it...I've
got a
> > Sun Ultra 5 that I had to change the NVRAM in, and got inquisitive) I
took the
> > 'SnapHat' battery off the NVRAM. I know this was not a clever thing to
do. I
> > know that I will probably end up putting the thing into a shop for
someone who
> > may understand the power problem to see, but is unlikely to recognise
any
> > printenv stuff. (Unless I want to pay a real fortune).
> >    Any ideas would be gratefully recieved. I would really hate to write
this
> > box off.
> >
> >                                                                Yours in
hope,
> > Liam
> > _______________________________________________
> > Sparcbook mailing list  -  Sparcbook at sunhelp.org
> > http://www.sunhelp.org/mailman/listinfo/sparcbook
>
> -- 
> Matthias Granberry
> matthias at utdallas.edu
> (214)432-2384
> _______________________________________________
> Sparcbook mailing list  -  Sparcbook at sunhelp.org
> http://www.sunhelp.org/mailman/listinfo/sparcbook