Need help troubleshooting Series 2 TiVo

An ice pack used to cool that selective component could also provide
useful information.

No, this is a phenomenally stupid idea!

Ice? As in water condensation? As in, death by electrocution? That's just
BAD ADVICE.

They make cans of propellant designed for this purpose, it's generally
referred to as 'freeze spray'. But any canned compressed air will suffice
if you're only doing a few things. Just turn it upside down, the propellant
will come out of there at quite a cold temperature. But unless you really
know what you're doing it'll be rather pointless. Spot freezing like that
only usually works if you've got a scope attached and know what signals to
be checking.

On Mar 29, 8:17*am, "Bill Kearney" wrote:
No, this is a phenomenally stupid idea!

Ice? *As in water condensation? *As in, death by electrocution? *That's just
BAD ADVICE.

I did not say ice. Ice pack. How does 5 and 12 volts electrocute
anyone? It does not. Did you read the part about not touching
anything in a power supply due to voltages (sometimes exposed) of 300
volts/

But voltages on the motherboard will not harm anyone - as noted by
another numbers - less than 50 volts.

Freeze spray is a handy tool only when using heat as a diagnostic
tool to isolate a failure. First the problem must be created (ie
using a hair dryer on highest heat). Then try to cure the problem by
selectively cooling a suspect. Freeze spary is very handy but not
easily obtained now that 'repair and part' shops no longer exist.
Using an Ice pack is a simple tool for cooling isolated compnents.

On Mar 29, 8:16*am, "Bill Kearney" wrote:
And you just post excessive blowhard nonsense.

Did you again forget the purpose of posting here - assistance to the
OP? Apparently forgetting is a recurring problem.

On Mar 29, 3:55*pm, w_tom wrote:
On Mar 29, 8:17*am, "Bill Kearney" wrote:

No, this is a phenomenally stupid idea!

Ice? *As in water condensation? *As in, death by electrocution? *That's just
BAD ADVICE.

* I did not say ice. *Ice pack. *

The result will be the same. Unless you operate your Tivo in a
refrigerator the ice pack will be below the due point and water will
form on the surface.

Where did you get the information that 140F is an ideal temperature
for a disk?

The OP here unfortunately does seem to have a sticky problem. It
could be a bad temperature sensor. I'm betting if you spend some time
searching, you will be able to find out where it is located. It will
likely be a 'through hold' components, and it may even be fastened to
a heatsink. Unless you are or have a friend who is an electronics
tinkerer you may just as well go out and buy a new Tivo. When it is
up and running, what does the temperature read on the GUI?

On Sat, 29 Mar 2008 13:37:53 -0700 (PDT), wrote:

On Mar 29, 3:55*pm, w_tom wrote:

On Mar 29, 8:17*am, "Bill Kearney" wrote:

No, this is a phenomenally stupid idea!

Ice? *As in water condensation? *As in, death by electrocution?
*That's just BAD ADVICE.

* I did not say ice. *Ice pack. *

The result will be the same. Unless you operate your Tivo in a
refrigerator the ice pack will be below the due point and water will
form on the surface.

You have, I think, an overestimatation of the conductivity of the rather
pure water that is condensation, and a fuzzy idea of what actually
causes electrocution.

--
25. No matter how well it would perform, I will never construct any sort of
machinery which is completely indestructible except for one small and
virtually inaccessible vulnerable spot.
--Peter Anspach's list of things to do as an Evil Overlord

In article , w_tom wrote:
On Mar 29, 8:17=A0am, "Bill Kearney" wrote:
No, this is a phenomenally stupid idea!

Ice? =A0As in water condensation? =A0As in, death by electrocution? =A0Tha=
t's just
BAD ADVICE.

I did not say ice. Ice pack. How does 5 and 12 volts electrocute
anyone?

Its not the volts that kill you but the Amps!


It does not. Did you read the part about not touching
anything in a power supply due to voltages (sometimes exposed) of 300
volts/

But voltages on the motherboard will not harm anyone - as noted by
another numbers - less than 50 volts.


Having your tongue on a telephone wire and having someone ring in can knock
you on your ass.


Freeze spray is a handy tool only when using heat as a diagnostic
tool to isolate a failure. First the problem must be created (ie
using a hair dryer on highest heat). Then try to cure the problem by
selectively cooling a suspect. Freeze spary is very handy but not
easily obtained now that 'repair and part' shops no longer exist.
Using an Ice pack is a simple tool for cooling isolated compnents.
Using anything that can lead to water condensation is purely retarded.

On Mar 29, 7:56*pm, "Peter H. Coffin" wrote:

You have, I think, an overestimatation of the conductivity of the rather
pure water that is condensation, and a fuzzy idea of what actually
causes electrocution.


LOL, well, I just had a fingercheck and blew away a about 8 paragraphs
on how electrcution can occur in this case, but let me just summarize
it in a few lines.

http://www.jp.horiba.com/story_e/con...ctivity_05.htm

But even if you assume the condensed water is 'pure', electrocution at
the low voltages (200V) in a tivo will be dominated by surface
conditions. The thin film of water between you and the 200V will
greatly reduce the resistance over a water free event even if both
surfaces were sterile since ever DI water will have 6-8 orders of
magnitude greater conductivity then air. The liquid film will also
dissolve any ionic contaminants on your skin and the other surface and
this will further reduce the surface resistance.

UL originally had the same thoughts on hair dryers as you do on water
and high voltage. In this case the water is not as clean, but the
distances through the water are far greater. Several hundred dead
people later, and GFIs are now a requirement.

On Mar 29, 3:37 pm, wrote:
Where did you get the information that 140F is an ideal temperature
for a disk?

Do you read manufacturer datasheets before posting? I do for more
than two generations. Posted are techniques for finding a problem
before fixing it - that contradicts the many popular myths from those
who never even read datasheets.

What happens if water gets between IC pins? If circuit does stop
operating (obviously without damage), then simply power off, dry
everything, and continue diagnostics. BTW, how do we clean newly
built electronic boards. Wash them in a dishwasher with water. How
many of us work where electronics are designed and built?

Electrocution from 5 and 12 volts is ridiculous - hyped fear. One
intentionally confuses 120 VAC on a hair dryer with 5 VDC on a
motherboard. He hypes fear based in technical naivety. Voltage below
50 V are quite safe. Those motherboard voltages cannot push dangerous
currents.

Those who don't learn technology and don't read data sheets may also
want to cure symptoms with 'more fans'. Instead, heat is an effective
diagnostic tool; not something to cure in that Tivo. "It could be this
or could be that" does not help the OP. Provide are diagnostic
techniques to find that problem. Heat is a diagnostic tool Voltage
measurements are a diagnostic tool that provide numbers. Numbers that
can elicit new information from the better informed posters who also
read datasheets.

w_tom writes:
On Mar 29, 3:37 pm, wrote:
Where did you get the information that 140F is an ideal temperature
for a disk?

Do you read manufacturer datasheets before posting? I do for more
than two generations. Posted are techniques for finding a problem
before fixing it - that contradicts the many popular myths from those
who never even read datasheets.

Reading and understanding are, apparently, two different things. While
the data sheet for a disk drive may list 57C as "operating temperature",
that's hardly the 'optimal' temperature, which is considerably less.

What happens if water gets between IC pins? If circuit does stop
operating (obviously without damage), then simply power off, dry

Why "obviously without damage"?

everything, and continue diagnostics. BTW, how do we clean newly
built electronic boards. Wash them in a dishwasher with water.

Of course this is not done with power applied to the board, and
generally before the board is stuffed.

How
many of us work where electronics are designed and built?

Electrocution from 5 and 12 volts is ridiculous - hyped fear. One

While the current in a TIVO will be limited at 5v and 12v, I've seen
5v supplies that can fry the unwary installed in large computers,
complete with 2 inch square aluminum bus-bars.

That same TIVO case also has mains current internally that is much more
hazardous.

scott

On Mar 31, 3:47 pm, (Scott Lurndal) wrote:
Why "obviously without damage"?

Obviously, when one has experience and knowledge of digital
electronics even dating back to DTL and TTL. Obviously no damage. If
water causes operational problems, simply shut down, dry, and
repower. Meanwhile, cooling is another good diagnostic tool to find a
temperature sensitive defect - to identify the suspect before fixing
anything.

Disk drives work fine even at 140 degrees F. We discover defective
hardware by using diagnostics such as heat. If hardware fails when
heated even with somethng so cool like a hair dryer, then that
hardware is completely defective. Heat is a diagnostic tool. If a
disk drive does not work at 140 degrees F, then that disk drive has
been identified as defective.

5 and 12 volts on a Tivo motherboard will not electrocute. Others
who deny this are simply hyping fear based in the same reasoning that
is also called junk science.

Provided are techniques to locate a failure.