Toshiba TV29C90 problem; Image fades to black...

[Steve]

Looks like I'm SOL. The traces each go through a 33 ohm resistor into
pins 3 & 4 of the uC. I imagine the prom got corrupted in the surge.
It has an EEPROM port, I bet if someone could flash it it'd work fine.
Oh well, I haven't tried the remote yet. This one was kind of fun,
the board was a PITA though, not meant for rework.

Steve

 

[Steve]

On Fri, 27 Feb 2009 18:46:54 -0600, Steve <s@s.c> wrote:

Looks like I'm SOL. The traces each go through a 33 ohm resistor into
pins 3 & 4 of the uC. I imagine the prom got corrupted in the surge.
It has an EEPROM port, I bet if someone could flash it it'd work fine.
Oh well, I haven't tried the remote yet. This one was kind of fun,
the board was a PITA though, not meant for rework.

Steve

Well, after some probing, it looks like it might not be wiped out
program. The divider input is 3.3V, but the output is 3.5V when open
circuit. The only thing else connected to the circuit is the uC. It
looks like the uC pin may be pulling the divider a little high causing
all the buttons to shift up, causing the higher ones to not work, and
the lower ones to be shifted one over. What is curious, though, is
that the menu button has its own pin, and it doesn't seem to work.
The menu button is only high or low, no divider output. When high, it
is pulled up to 3.5v as well, instead of 3.3v.

 

On 27 Feb, 19:58, less...@gmail.com wrote:

This is Hunter Fans Digital Thermostat Model 44360.
It has worked to control my gas furnace for 6 years.
I like it's design and features. Hunters have a bad rep with
service people from what I've read in HAVC forums. But
I like mine and would like to repair it.

Lately its calibration is off by 2 to 4 degrees. I know this
by comparing it with three other thermostats: a new Honeywell
replacement digital and 2 old Honeywell mercury-switched thermos. In
addition, a room thermometer confirms the others' readouts.

As the room reaches warmer temps the Hunter's readout will
become more unstable and gravitate towards the 4-degree
range.

All this may or may not have started after I knocked the Hunter off
the wall. There was no apparent damages.

Looking at the cb there is a protected part that sticks out.
It has a plastic guard around it. The circuit board has the marking
"RT" .  It appears to be a very small glass bead or
mini-mini LED type of device.  Exhaling warm breath or placing my
fingers around the guard will cause the readout to rise.

Have you blown the dust out of this area?

Chris

 

[Ron]

Graeme Dods wrote:

Ron <ron@lunevalleyaudio.com> wrote in
news:FLudnZqLNc8QnzXUnZ2dnUVZ8sPinZ2d@bt.com:

When I turn out the light - a single 60 watt incandescant bulb, the fan
behaves normally - no pulsing or noises - for the remainder of it`s time.

Are you standing at the open door as you turn it on/off? I know the speed
of our bathroom fan alters quite drastically if the door is open and
slightly if there's a reasonable sized obstruction (e.g. me) in the
doorway. Or perhaps there's some dodgy connection and the increased load of
the light slows the fan a little?

No, it happens door open or closed, and once it`s started, it continues
until the light is turned off.

A high resistance connection somewhere is probably the answer. Next time
it happens I might ry removing the bulb with the light still on to see
what effect that has.

One other thing, this only happens when it`s windy outside, on a calm
day it behaves normally.

Same issue as the door obstruction - differences in pressure so the fan
works harder/less or runs slower/faster.

On the times it`s working normally, you can hear the effects of the wind
slowing the fan as it blows into the duct, but it`s not quite the same.

Ron

 

[Ron]

Bernard Peek wrote:

In message <FLudnZqLNc8QnzXUnZ2dnUVZ8sPinZ2d@bt.com>, Ron
ron@lunevalleyaudio.com> writes
Here`s a thing, my bathroom fan - standard through wall 4.5 inch kinda
thing - makes a thrub thrub thrub noise when operating. It's a similar
sound to when a plain bearing is worn out, and you can see the blades
slowing and speeding up rythmicaly roughly once per second. The fan is
wired so that it starts when the bathroom light is turned on, and
continues for several minutes after the light is turned off.

but...

When I turn out the light - a single 60 watt incandescant bulb, the
fan behaves normally - no pulsing or noises - for the remainder of
it`s time.

One other thing, this only happens when it`s windy outside, on a calm
day it behaves normally.

I have one or two theories of my own, but I wonder if there`s any
informed comment (or wild guesses) from the brains trust as to why
this should happen?

The interaction with the wind suggests that it's some sort of resonance
effect. Perhaps the wind blowing across the mouth of the duct or around
the building is forming a Helmholtz resonator.

The interaction between the fan and the light suggests that the wind is
only affecting the fan when the supply power is shared between the light
and the fan. They aren't likely to be wired in series so the issue may
be a voltage drop caused by excessive resistance in the supply cables or
switches.

My thoughts, but I wouldn`t have thought a 60 watt bulb would have much
effect on a syncronous motor, but who knows.

Ron

 

[Ron]

Sn!pe wrote:

Ron <ron@lunevalleyaudio.com> wrote:

Here`s a thing, my bathroom fan - standard through wall 4.5 inch kinda
thing - makes a thrub thrub thrub noise when operating. It's a similar
sound to when a plain bearing is worn out, and you can see the blades
slowing and speeding up rythmicaly roughly once per second. The fan is
wired so that it starts when the bathroom light is turned on, and
continues for several minutes after the light is turned off.

but...

When I turn out the light - a single 60 watt incandescant bulb, the fan
behaves normally - no pulsing or noises - for the remainder of it`s time.

One other thing, this only happens when it`s windy outside, on a calm
day it behaves normally.

I have one or two theories of my own, but I wonder if there`s any
informed comment (or wild guesses) from the brains trust as to why this
should happen?

Ron(UK)

Crossposted to uk.rec.sheds cos it`s the kind of thing people in sheds
like to sagaciate about.

Darn rite.

I have a very similar situation; when cold our bathroom extractor fan
squeals like mad for half a minute or so, then goes to a loudish hum
(still rotating) then quietens down to normal operation. I put it down
to temperature: either the spindle and bearing expanding at different
rates, or maybe the lube-oil (as if) is changing viscosity with
temperature.

That`s caused by a shortage of cramolin I thnk

 

[Ken]

Ron wrote:

Graeme Dods wrote:
Ron <ron@lunevalleyaudio.com> wrote in
news:FLudnZqLNc8QnzXUnZ2dnUVZ8sPinZ2d@bt.com:

When I turn out the light - a single 60 watt incandescant bulb, the
fan behaves normally - no pulsing or noises - for the remainder of
it`s time.

Are you standing at the open door as you turn it on/off? I know the
speed of our bathroom fan alters quite drastically if the door is open
and slightly if there's a reasonable sized obstruction (e.g. me) in
the doorway. Or perhaps there's some dodgy connection and the
increased load of the light slows the fan a little?

No, it happens door open or closed, and once it`s started, it continues
until the light is turned off.

A high resistance connection somewhere is probably the answer. Next time
it happens I might ry removing the bulb with the light still on to see
what effect that has.

Why don't you hang a DVM across the leads of the fan to see what
happens to the voltage when the light is switched on? I think your
theory is probably correct.

One other thing, this only happens when it`s windy outside, on a
calm day it behaves normally.

Same issue as the door obstruction - differences in pressure so the
fan works harder/less or runs slower/faster.

On the times it`s working normally, you can hear the effects of the wind
slowing the fan as it blows into the duct, but it`s not quite the same.

Ron

 

[Carl LHS Williams]

In article <FLudnZqLNc8QnzXUnZ2dnUVZ8sPinZ2d@bt.com>,
Ron <ron@lunevalleyaudio.com> wrote:

Here`s a thing, my bathroom fan - standard through wall 4.5 inch kinda
thing - makes a thrub thrub thrub noise when operating. It's a similar
sound to when a plain bearing is worn out, and you can see the blades
slowing and speeding up rythmicaly roughly once per second. The fan is
wired so that it starts when the bathroom light is turned on, and
continues for several minutes after the light is turned off.

but...

When I turn out the light - a single 60 watt incandescant bulb, the fan
behaves normally - no pulsing or noises - for the remainder of it`s time.

One other thing, this only happens when it`s windy outside, on a calm
day it behaves normally.

I have one or two theories of my own, but I wonder if there`s any
informed comment (or wild guesses) from the brains trust as to why this
should happen?

Some sorta resonance, I guess.

Prolly whatever timer wossname keeps the fan on does so via summat,
e.g. a triac, which runs it at a slightly different voltage or duty
cycle or summat (might even be deliberate - it might be designed to
run a bit slower when in light-off mode).

I guess it *might* involve some horrendous subtlety to do with the
resistance of the bulb and reflections of electrical motor noise down
yer wires, and a worn bearing/motor teetering on the edge of resonating,
but my guess is that if you stick a 'scope across the motor, you'll
find it's supplied with differently shaped or sized electrickery
in the two modes, by enough of a margin to account for a different
running speed, which would also account for hitting or not hitting
a resonant mode. Yer wind will speed up or slow down the fan overall,
I guess - mebbe completely still air allows it to cavitate and run
faster?

 

[tommi]

On Sat 28Feb 15:08, att <n2nbe@att.net> wrote

"tommi" <billgates@microsoft.com> wrote:


Can you help me ID a small capacitor. The photo shows two
identical capacitors which are marked with: 225F *
Underneath that marking is a + sign followed by a long line.

http://i39.tinypic.com/2kn8u0.jpg showing AA battery holder.

(1) Are they likely to be tantalum capacitors?

(2) Does that marking mean they are 220nF or are they 220pF? Or
some other value?


2.2uf, voltage unknown. They sure look like tantalums.

I've heard tantalum capacitors can get noisy or break down over time.

The device in my photo is used to power a microphone. So any noise
from it would be very unwelcome.

Is it worth changing those capacitors to another type? Would
something like a polyester capacitor have enough capacity for 2.2uF
and still be physically small enough to fit in the space on the
circuit board shown in my photo?

http://i39.tinypic.com/2kn8u0.jpg




--
nb:groups widened

 

[Franc Zabkar]

On Fri, 27 Feb 2009 21:30:06 -0600, Steve <s@s.c> put finger to
keyboard and composed:

On Fri, 27 Feb 2009 18:46:54 -0600, Steve <s@s.c> wrote:

Looks like I'm SOL. The traces each go through a 33 ohm resistor into
pins 3 & 4 of the uC. I imagine the prom got corrupted in the surge.
It has an EEPROM port, I bet if someone could flash it it'd work fine.
Oh well, I haven't tried the remote yet. This one was kind of fun,
the board was a PITA though, not meant for rework.

Steve

Well, after some probing, it looks like it might not be wiped out
program. The divider input is 3.3V, but the output is 3.5V when open
circuit. The only thing else connected to the circuit is the uC. It
looks like the uC pin may be pulling the divider a little high causing
all the buttons to shift up, causing the higher ones to not work, and
the lower ones to be shifted one over. What is curious, though, is
that the menu button has its own pin, and it doesn't seem to work.
The menu button is only high or low, no divider output. When high, it
is pulled up to 3.5v as well, instead of 3.3v.

Why not install a buffer between pin 2 and the switch commons? You
could use a 3.3V rail-to-rail op-amp wired as a voltage follower. I've
"repaired" faulty I/O pins on uCs using similar methods. It appears
that the Menu button is unrecoverable, though.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

 

[whit3rd]

On Feb 28, 10:35 am, tommi <billga...@microsoft.com> wrote:

I've heard tantalum capacitors can get noisy or break down over time.

The device in my photo is used to power a microphone.

Those are 'orange drop' style tantalum capacitors. If it's
used for power supply bypassing, there's no problem.
If, however, it's used for DC blocking the capacitor
could be in series with your microphone signal.

The seal of such capacitors is fragile (i.e. handling or
aging can break 'em open), and a good axial-package
aluminum might be more reliable...

I wouldn't replace it, myself, but it wouldn't be my first
choice for the application.

 

[Rusty_Hinge]

The message <beKdnbm6IPeKhTTUnZ2dnUVZ8hQLAAAA@bt.com>
from Ron <ron@lunevalleyaudio.com> contains these words:

The interaction between the fan and the light suggests that the wind is
only affecting the fan when the supply power is shared between the light
and the fan. They aren't likely to be wired in series so the issue may
be a voltage drop caused by excessive resistance in the supply cables or
switches.

My thoughts, but I wouldn`t have thought a 60 watt bulb would have much
effect on a syncronous motor, but who knows.

Just supposing the length of the line to the bulb and the line to the
motor are in such a proportion to each other that you get a resonance,
cancelling/attenuating part of the emf to the motor.

Motor slows fractionally, cancellation/attenuation is interrupted, motor
accelerates until...

--
Rusty
Growing old is mandatory; growing up is optional.
Direct reply to: horrid dot squeak snailything zetnet point co period uk

 

[David Nebenzahl]

On 2/28/2009 5:16 PM Rusty_Hinge spake thus:

The message <beKdnbm6IPeKhTTUnZ2dnUVZ8hQLAAAA@bt.com
from Ron <ron@lunevalleyaudio.com> contains these words:

The interaction between the fan and the light suggests that the wind is
only affecting the fan when the supply power is shared between the light
and the fan. They aren't likely to be wired in series so the issue may
be a voltage drop caused by excessive resistance in the supply cables or
switches.

My thoughts, but I wouldn`t have thought a 60 watt bulb would have much
effect on a syncronous motor, but who knows.

Just supposing the length of the line to the bulb and the line to the
motor are in such a proportion to each other that you get a resonance,
cancelling/attenuating part of the emf to the motor.

Motor slows fractionally, cancellation/attenuation is interrupted, motor
accelerates until...

Totally preposterous. You're reaching. No such inductance in house
wiring would be strong enough to have any such effects here.


--
Personally, I like Vista, but I probably won't use it. I like it
because it generates considerable business for me in consulting and
upgrades. As long as there is hardware and software out there that
doesn't work, I stay in business. Incidentally, my company motto is
"If this stuff worked, you wouldn't need me".

- lifted from sci.electronics.repair

 

[Michael Kennedy]

"David Nebenzahl" <nobody@but.us.chickens> wrote in message
news:49a9f1aa$0$2707$822641b3@news.adtechcomputers.com...

On 2/28/2009 5:16 PM Rusty_Hinge spake thus:

The message <beKdnbm6IPeKhTTUnZ2dnUVZ8hQLAAAA@bt.com
from Ron <ron@lunevalleyaudio.com> contains these words:

The interaction between the fan and the light suggests that the wind
is only affecting the fan when the supply power is shared between the
light and the fan. They aren't likely to be wired in series so the
issue may be a voltage drop caused by excessive resistance in the
supply cables or switches.

My thoughts, but I wouldn`t have thought a 60 watt bulb would have much
effect on a syncronous motor, but who knows.

Just supposing the length of the line to the bulb and the line to the
motor are in such a proportion to each other that you get a resonance,
cancelling/attenuating part of the emf to the motor.

Motor slows fractionally, cancellation/attenuation is interrupted, motor
accelerates until...

Totally preposterous. You're reaching. No such inductance in house wiring
would be strong enough to have any such effects here.


--
Personally, I like Vista, but I probably won't use it. I like it
because it generates considerable business for me in consulting and
upgrades. As long as there is hardware and software out there that
doesn't work, I stay in business. Incidentally, my company motto is
"If this stuff worked, you wouldn't need me".

- lifted from sci.electronics.repair

Preposterous but interesting reading. I think that this problem is
probably quite simple, and would more than likely be solved by a new fan.
Have you tried unscrewing the 60w bulb? Does it still have trouble then? I'm
a little unsure of how exactly this thing works after you turn the switch
off, since I've never seen a fan like this. Your problem could be related to
that cirucit somehow, depending on how it is implemented. I think the most
likely problem is air pressure though and obstructions creating a vacume /
stressing the fan like others have said.

 

[Steve]

On Sun, 01 Mar 2009 06:46:41 +1100, Franc Zabkar
<fzabkar@iinternode.on.net> wrote:

On Fri, 27 Feb 2009 21:30:06 -0600, Steve <s@s.c> put finger to
keyboard and composed:

On Fri, 27 Feb 2009 18:46:54 -0600, Steve <s@s.c> wrote:

Looks like I'm SOL. The traces each go through a 33 ohm resistor into
pins 3 & 4 of the uC. I imagine the prom got corrupted in the surge.
It has an EEPROM port, I bet if someone could flash it it'd work fine.
Oh well, I haven't tried the remote yet. This one was kind of fun,
the board was a PITA though, not meant for rework.

Steve

Well, after some probing, it looks like it might not be wiped out
program. The divider input is 3.3V, but the output is 3.5V when open
circuit. The only thing else connected to the circuit is the uC. It
looks like the uC pin may be pulling the divider a little high causing
all the buttons to shift up, causing the higher ones to not work, and
the lower ones to be shifted one over. What is curious, though, is
that the menu button has its own pin, and it doesn't seem to work.
The menu button is only high or low, no divider output. When high, it
is pulled up to 3.5v as well, instead of 3.3v.

Why not install a buffer between pin 2 and the switch commons? You
could use a 3.3V rail-to-rail op-amp wired as a voltage follower. I've
"repaired" faulty I/O pins on uCs using similar methods. It appears
that the Menu button is unrecoverable, though.

- Franc Zabkar

Good solution, shouldn't take more than a few parts & I could probably
just glue them to an unpopulated section of the board. This was kind
of a botched repair anyway, I had to guess at equivalent parts and the
board was damaged during the rework. Oh well, can't win them all.

Thanks,
Steve

 

[Ron]

Ken wrote:

Ron wrote:
Graeme Dods wrote:
Ron <ron@lunevalleyaudio.com> wrote in
news:FLudnZqLNc8QnzXUnZ2dnUVZ8sPinZ2d@bt.com:

When I turn out the light - a single 60 watt incandescant bulb, the
fan behaves normally - no pulsing or noises - for the remainder of
it`s time.

Are you standing at the open door as you turn it on/off? I know the
speed of our bathroom fan alters quite drastically if the door is
open and slightly if there's a reasonable sized obstruction (e.g. me)
in the doorway. Or perhaps there's some dodgy connection and the
increased load of the light slows the fan a little?

No, it happens door open or closed, and once it`s started, it
continues until the light is turned off.

A high resistance connection somewhere is probably the answer. Next
time it happens I might ry removing the bulb with the light still on
to see what effect that has.

Why don't you hang a DVM across the leads of the fan to see what
happens to the voltage when the light is switched on? I think your
theory is probably correct.

It`s built into the wall. I can`t try removing the bulb as today is calm
and the fan behaves perfectly.

Ron

 

[Ron]

Rusty_Hinge wrote:

The message <beKdnbm6IPeKhTTUnZ2dnUVZ8hQLAAAA@bt.com
from Ron <ron@lunevalleyaudio.com> contains these words:

The interaction between the fan and the light suggests that the wind is
only affecting the fan when the supply power is shared between the light
and the fan. They aren't likely to be wired in series so the issue may
be a voltage drop caused by excessive resistance in the supply cables or
switches.

My thoughts, but I wouldn`t have thought a 60 watt bulb would have much
effect on a syncronous motor, but who knows.

Just supposing the length of the line to the bulb and the line to the
motor are in such a proportion to each other that you get a resonance,
cancelling/attenuating part of the emf to the motor.

Motor slows fractionally, cancellation/attenuation is interrupted, motor
accelerates until...

Well, I was thinking maybe a slight alteration in waveform when the bulb

is in circuit, but a 60 watt bulb? on 240 volts? nah! Hey I might try a
lower and highter wattage lamp, just to see...

Ron

 

[Ron]

Michael Kennedy wrote:

"David Nebenzahl" <nobody@but.us.chickens> wrote in message
news:49a9f1aa$0$2707$822641b3@news.adtechcomputers.com...
On 2/28/2009 5:16 PM Rusty_Hinge spake thus:

The message <beKdnbm6IPeKhTTUnZ2dnUVZ8hQLAAAA@bt.com
from Ron <ron@lunevalleyaudio.com> contains these words:

The interaction between the fan and the light suggests that the wind
is only affecting the fan when the supply power is shared between the
light and the fan. They aren't likely to be wired in series so the
issue may be a voltage drop caused by excessive resistance in the
supply cables or switches.
My thoughts, but I wouldn`t have thought a 60 watt bulb would have much
effect on a syncronous motor, but who knows.
Just supposing the length of the line to the bulb and the line to the
motor are in such a proportion to each other that you get a resonance,
cancelling/attenuating part of the emf to the motor.

Motor slows fractionally, cancellation/attenuation is interrupted, motor
accelerates until...
Totally preposterous. You're reaching. No such inductance in house wiring
would be strong enough to have any such effects here.


--
Personally, I like Vista, but I probably won't use it. I like it
because it generates considerable business for me in consulting and
upgrades. As long as there is hardware and software out there that
doesn't work, I stay in business. Incidentally, my company motto is
"If this stuff worked, you wouldn't need me".

- lifted from sci.electronics.repair

Preposterous but interesting reading. I think that this problem is
probably quite simple, and would more than likely be solved by a new fan.
Have you tried unscrewing the 60w bulb? Does it still have trouble then? I'm
a little unsure of how exactly this thing works after you turn the switch
off, since I've never seen a fan like this. Your problem could be related to
that cirucit somehow, depending on how it is implemented. I think the most
likely problem is air pressure though and obstructions creating a vacume /
stressing the fan like others have said.

Well it`s not so much a problem, just as the header says, an
interseting phenomenon. I`m neither going to lose any sleep over it or
start tearing the plasterboard apart to find out. The wind doesn't blow
steady, so I don't think it`s any kind of resonance effect.

One other thing, when it`s windy, to cut down draughts, we block the
inside side of the fan with a small square of cardboard held on with
velco. The hunting happens whether or not the fan is blocked.

Ron

 

[Ron]

nev young wrote:

On 27/02/09 15:11, Ron wrote:
I have one or two theories of my own, but I wonder if there`s any
informed comment (or wild guesses) from the brains trust as to why
this should happen?

My guess is

When the light is on the fan timer is constantly being re-triggered,
which will cause the fan to run at its max power as the tirac gets
triggered as soon as possible in each mains cycle.

When the light is off the fan timer is run only from the timer circuit
which will cause the fan to run slightly slower as the tirac gets
triggered a little later in each mains cycle.

That`s a plausible sounding answer, removing the bulb should support
that theory I think.

Ron

 

[Sleepalot]

Ron <ron@lunevalleyaudio.com> wrote:

It`s built into the wall. I can`t try removing the bulb as today is calm
and the fan behaves perfectly.

Well there's your answer, no?

--
Sleepalot aa #1385