Date: Thu, 3 Mar 2005 10:59:13 -0800
From: <[EMAIL PROTECTED]>
Subject: RE: [LIB] Mr. Barnacle
I have an old L70 that I have never used and never opened up. My main
Libby is the L100, which I bought new.
Speaking in generalities about fuses, since I have not seen one in
either machine, here is what a typical design engineer would do:
1. If a fuse was required to protect the device from catastrophic
failure, he would include a fuse that could be replaced easily.
("Easily" could mean by a Toshiba repair person, or by the customer -
but it would still be accessible by someone.)
2. In rare instances, he could put in what is called a "fusible link".
This is usually thermally tripped, and functions exactly as a fuse that
was tripped due to over current. These links are usually soldered in and
not meant for anyone but repair personnel to repair.
3. Fuses come in limited sizes / shapes, but they would not be confused
with capacitors or resistors.
4. A fuse that prevents the power from being applied to the computer is
probably located very close to the connector where the power supply
comes in to the computer.
When you see large quantities of the same shape device, it is not a
fuse. Fuses are a last resort to protect the circuit - it is assumed the
problem causing the fuse to "blow" will be obvious to the person trying
to repair it, otherwise just putting in a new fuse would cause the new
fuse to also "blow".
I will see if I can open up my L100 and tell you if there are any fuses
in it.
Dick
-----Original Message-----
From: Matt Hanson [mailto:[EMAIL PROTECTED]
Sent: Thursday, March 03, 2005 2:34 AM
To: Libretto
Subject: RE: [LIB] Mr. Barnacle
Date: Wed, 2 Mar 2005 23:32:09 -0800 (PST)
From: Matt Hanson <[EMAIL PROTECTED]>
Subject: RE: [LIB] Mr. Barnacle
Hey Dick...
--- [EMAIL PROTECTED] wrote:
>
> Matt, if the component measures zero across it, and that component is
> the fuse, it is good. Other devices, like resistors, may or may not be
> good.
Doh!! Yeah... I meant to write... "if the resistance across the fuse is
>infinite<, then it's blown".
Are you familiar with what fuses look like on the 50/70 & 100/110 MBs
Richard? I just opened up my 70 and found the fuse that Neil had me
work on is quite large compared to similar parts on the 110 MB. It's
one of two such components on the 70 that's visible without removing the
heat sync.
The 110 has nothing that looks similar, though I haven't pull the
heatsink on it to peak underneath. The fuse from the 70 wouldn't even
fit under a heatsink. There are about a dozen similar components on the
110 MB that are about 1/3 the size of that 70 fuse, and quite a number
even smaller.
It doesn't seem any of those would be a fuse. But I'd think a fuse
would look physically different, unless there are 1-2 dozen fuses on the
board.
That doesn't seem likely.
> Usually you are measuring more than just the resistor when you place
> your meter leads across the resistor - you also get parallel paths
> from other components connected to the resistor.
That's where my circuit testing abilities become severely handicapped.
Measuring one component on its own I can deal with. Components within
circuits on the other hand.... [EMAIL PROTECTED](*%!
Matt
> This is another case where a copy of the schematic would be extremely
> helpful. I sent a letter off to Toshiba support a few weeks ago
> requesting the schematic, but received no reply.
>
> Anyone have a contact inside Toshiba?
>
> Dick
>
> -----Original Message-----
> From: Matt Hanson [mailto:[EMAIL PROTECTED]
> Sent: Wednesday, March 02, 2005 2:30 PM
> To: Libretto
> Subject: Re: [LIB] Mr. Barnacle
>
>
> Date: Wed, 2 Mar 2005 11:29:09 -0800 (PST)
> From: Matt Hanson <[EMAIL PROTECTED]>
> Subject: Re: [LIB] Mr. Barnacle
>
>
> --- barnacle <[EMAIL PROTECTED]> wrote:
> > On Sunday 27 February 2005 23:35, you wrote:
> >
> > > I recall you had me test to see if the resistance across the fuse
> > > on
>
> > > the L70 was zero, and then solder a fuse wire across the top of
> > > the
> > > case. The L70 is still going after all these years. I may just
> > > pull
> > the L110 out and see if I can spot any fuses in it.
> >
> > Um, basically that was what I did - I looked for things in
> > fuse-style
> > packages - look for quite a large package and markings like '3.15'
or
>
> > similar.
>
> Hmmm.... I've checked the 110 MB. I haven't yet taken the 70 apart
> to look at the fuse we worked on. But it seems it looked exactly the
> same as a number of other components. White case with silver metal
> caps on either end. The 110 MB has dozens of components that look
> like that. And it seems the 70 did too, tho' my memory is always
> pretty bad.
>
> I don't know much about circuit testing. Would any such component
> that measures 0 ohms across it be bad? I know some resisters can
> measure near zero, yet still are what the circuit calls for.
>
> Will have to take the 70 apart. I now have the original 100 MB
> running in the place of the dead 110 MB, and am wondering if clocking
> it to 233 might be more stable than when I had it at 266. It was
> always shutting itself down at 266 due to overheating. W2K is
> obviously impossible to run at 166.
>
> Matt
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