I have a dead HP/Compak NX9110 laptop. Of course HP have quoted a new
motherboard price that is higher than the value of the laptop.

After investigating a ~3 Hz ticking sound, I have narrowed the problem down
to a MAX1902 multiple output switching regulator which regulates the 3V and
5V supplies. Nice looking device really. It looks like the device is being
shut down via the Time/ON5 input. However, I can't see what is driving this
input (naturally it's a multilayer board making further diagnosis
difficult).

It doesn't seem to be going into current limit, or tripping either the
overvoltage or undervoltage circuits.

What would really help is a mainboard schematic. Does anyone have one they
can scan, or know where to find one?

Thanks,
Alf

Alf Katz wrote:

> What would really help is a mainboard schematic. Does anyone have one they
> can scan, or know where to find one?

You'll never find one; these devices are not serviceable at the
component level and all accessible documentation will, at best, give
you only a subassembly-level guide.

In many cases, if you have standby voltage present on the board and it
won't fully power up for some reason, the signals in question will
trace back to a slave micro that manages power and other misc.
functions. It's usually an 8-bit micro. In modern machines this is
often an all-in-one chip containing the keyboard and pointing device
interface also. Often the "no switch on" decision is being made
internally to that slave micro based on other inputs, the state of
which you have to infer.

I'd try hotwiring the regulator "on" and see what happens - given that
the board is garbage already. However I've rarely been successful at
fixing component-level problems on laptop mainboards; without design
intent information, everything has to be analyzed from first principles.

Schematics don't exist outside of the development engineering
organization. Even the service manuals don't have them.


Alf Katz wrote:
> I have a dead HP/Compak NX9110 laptop. Of course HP have quoted a new
> motherboard price that is higher than the value of the laptop.
>
> After investigating a ~3 Hz ticking sound, I have narrowed the problem down
> to a MAX1902 multiple output switching regulator which regulates the 3V and
> 5V supplies. Nice looking device really. It looks like the device is being
> shut down via the Time/ON5 input. However, I can't see what is driving this
> input (naturally it's a multilayer board making further diagnosis
> difficult).
>
> It doesn't seem to be going into current limit, or tripping either the
> overvoltage or undervoltage circuits.
>
> What would really help is a mainboard schematic. Does anyone have one they
> can scan, or know where to find one?
>
> Thanks,
> Alf
>
>

"Barry Watzman" <> wrote in message
news:
> Schematics don't exist outside of the development engineering
> organization. Even the service manuals don't have them.

A company named SAMS used to reverse engineer electronic devices and
then make a schematic for it as well. I recall they did this for many
computers back in the 80's. I don't know if they are still around. As
they went back for decades for TVs and radios. I should still have my
SAMS schematics for my Commodore VIC-20. I have my Commodore SX-64
(first color luggable) schematics straight from Commodore themselves.
Ah... things isn't like this anymore, eh?

--
Bill

BillW50 wrote:

> A company named SAMS used to reverse engineer electronic devices and
> then make a schematic for it as well. I recall they did this for many
> computers back in the 80's. I don't know if they are still around. As

Technology to do this has become much easier. There's software now that
will take as input standard X-rays of a PCB and create a netlist from
that more or less automatically.

The reason it's not done commercially any more is because the
information is useless. 99% of the time even if you can work out which
part is actually faulty, this merely leads you to "Replace ASIC that
isn't available off the shelf". And the debugging time, at $85 per hour
or more, rapidly approaches the $500 cost of a new machine.

Hello Bill
Do you have by any chance a circuit diagram for the English made Commodore
C64.
I have 3 faulty C64 and one complete working and one without sound.
Want to tackle them sometime in the future.
Greetings
Bert

You are talking about "Sams Photofacts", and they were not reverse
engineered, they were based on information voluntarily supplied by
manufacturers. They were the source of information used by repair shops
for TVs, radios, stereos and car radios. They did some computers and
some monitors back in the 1980's.

They've been around since 1946 and are still in business:

http://www.samswebsite.com/photofacts.html

But you won't find schematics of laptops, in fact I don't think you will
generally find computers at all.


wrote:
> BillW50 wrote:
>
>> A company named SAMS used to reverse engineer electronic devices and
>> then make a schematic for it as well. I recall they did this for many
>> computers back in the 80's. I don't know if they are still around. As
>
> Technology to do this has become much easier. There's software now that
> will take as input standard X-rays of a PCB and create a netlist from
> that more or less automatically.
>
> The reason it's not done commercially any more is because the
> information is useless. 99% of the time even if you can work out which
> part is actually faulty, this merely leads you to "Replace ASIC that
> isn't available off the shelf". And the debugging time, at $85 per hour
> or more, rapidly approaches the $500 cost of a new machine.
>

In all the years I've been dealing with Wintel personal computers and notebooks,
I have never seen a vendor-supplied schematic for a board. The best one can
hope for is a very good service manual with decent drawings showing how to take
apart a notebook, the order of removing things, and drawings of photos of
individual parts. Dell and IBM/Lenovo have been consistently good at providing
such info. HPaq not quite so good, but I have gotten a few Compaq notebook
service manuals. Ditto Gateway/eMachines. But then Toshiba and Sony provide
nothing at all to the consumer in the way of system maintenance info... Ben
Myers

On Sun, 19 Nov 2006 16:14:20 -0500, Barry Watzman <>
wrote:

>You are talking about "Sams Photofacts", and they were not reverse
>engineered, they were based on information voluntarily supplied by
>manufacturers. They were the source of information used by repair shops
>for TVs, radios, stereos and car radios. They did some computers and
>some monitors back in the 1980's.
>
>They've been around since 1946 and are still in business:
>
>http://www.samswebsite.com/photofacts.html
>
>But you won't find schematics of laptops, in fact I don't think you will
>generally find computers at all.
>
>
> wrote:
>> BillW50 wrote:
>>
>>> A company named SAMS used to reverse engineer electronic devices and
>>> then make a schematic for it as well. I recall they did this for many
>>> computers back in the 80's. I don't know if they are still around. As
>>
>> Technology to do this has become much easier. There's software now that
>> will take as input standard X-rays of a PCB and create a netlist from
>> that more or less automatically.
>>
>> The reason it's not done commercially any more is because the
>> information is useless. 99% of the time even if you can work out which
>> part is actually faulty, this merely leads you to "Replace ASIC that
>> isn't available off the shelf". And the debugging time, at $85 per hour
>> or more, rapidly approaches the $500 cost of a new machine.
>>

"Barry Watzman" <> wrote in message
news:
> You are talking about "Sams Photofacts", and they were not reverse
> engineered, they were based on information voluntarily supplied by
> manufacturers...

[snip]

> http://www.samswebsite.com/photofacts.html

Really? Sams Photofacts claims reversed engineering like I said.

*** PHOTOFACT® is recognized as the world's best and most accurate
service documentation available today. For over 55 years, Sams has used,
and continues to use, a process called "reverse engineering" to create
Photofact. Reverse Engineering is a process in which the equipment is
disassembled and each component and circuit is checked and documented.
Each Sams schematic is drawn accurately in a consistent, standardized
format which makes it easy to use and simple to understand. ***

--
Bill

"Bert" <lijbertv_at_xsinet_dot_co_dot_za> wrote in message
news:
> Hello Bill
> Do you have by any chance a circuit diagram for the English made
> Commodore C64.
> I have 3 faulty C64 and one complete working and one without sound.
> Want to tackle them sometime in the future.
> Greetings
> Bert

I have the service manual for a Commodore SX-64 in storage, which is
electronically the same. But 8-bit computers like the Commodores are
easy to repair even without a schematic. See:

http://www.zimmers.net/anonftp/pub/c...s/c-diag10.txt

No sound is usually the SID chip, 6581

--
Bill