Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1   Report Post  
Posted to sci.electronics.repair,sci.electronics.design
external usenet poster
 
Posts: 411
Default Saving LCD screens that were under water

I had some electronics in a storage building, which flooded. I figured
that most of it is junk, but I wiped it clean and put some of the stuff
outside in the sun to bake dry. So far, much of it works. But two
items, a GPS and a Police Scanner, both with LCD screens have very faint
screens. I kind of think the water affected the LCD screens.

Is there any way to get them LCD screens to work (other than replacing
them)?

  #5   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 1,625
Default Saving LCD screens that were under water

On Thursday, June 7, 2018 at 8:01:54 AM UTC-4, Fox's Mercantile wrote:

Throw the stuff out and spend your time fixing the roof.


That IS rather ironic coming from you - ;-)

Peter Wieck
Melrose Park, PA


  #8   Report Post  
Posted to sci.electronics.repair,sci.electronics.design
external usenet poster
 
Posts: 4,045
Default Saving LCD screens that were under water

On Thu, 07 Jun 2018 00:15:38 -0500, wrote:

I had some electronics in a storage building, which flooded. I figured
that most of it is junk, but I wiped it clean and put some of the stuff
outside in the sun to bake dry. So far, much of it works. But two
items, a GPS and a Police Scanner, both with LCD screens have very faint
screens. I kind of think the water affected the LCD screens.

Is there any way to get them LCD screens to work (other than replacing
them)?


No. LCD panels are not hermitically sealed. If it were sealed, the
glass would bulge when the panel becomes hot. There is a tiny hole,
usually near the bottom of the screen, to equalize the air pressure on
both sides of the glass. If you immerse the panel in cold water, the
air inside the glass screen will contract, causing a partial vacuum,
which will suck the water into the panel. If you remove the frame
from the panel, you can see the water inside the panel.

I had the bright idea of heating the panel to build up internal air
pressure and thus push the water out of the panel. That didn't work.
I also tried using a vacuum pump on the outside to help suck out the
water, but that also failed. Best results were to attach something
that wicks water (cotton balls, rice, desiccant) at the hole, to suck
out the water via capillary action. Even so, I was only able to
extract a tiny amount of water, leaving most of it inside the panel.
When the price of panels dropped dramatically, I gave up on trying to
fix these.

The GPS and radio scanner probably have corrosion damaged PCB traces.
If you can find the damage and repair the traces, both can be fixed.
--
Jeff Liebermann

150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
  #9   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 411
Default Saving LCD screens that were under water

On Thu, 7 Jun 2018 09:38:48 -0400, Phil Hobbs
wrote:

On 06/07/2018 09:11 AM, Fox's Mercantile wrote:
On 6/7/18 7:32 AM, wrote:
On Thursday, June 7, 2018 at 8:01:54 AM UTC-4, Fox's Mercantile wrote:

Throw the stuff out and spend your time fixing the roof.

That IS rather ironic coming from you - ;-)


My roof leaks. I have enough sense to have tarps protecting stuff.



Could have been surface water. My back yard occasionally floods
too--it's a very pleasant place but is a former pond bottom.

Cheers

Phil Hobbs
(Who has a deep affection for his storm drain)


It was not the roof, a water pipe broke the main brass valve. The water
was shut off at that valve and there was heat tape on the valve and the
pipe below that valve, but that heat tape must have failed. Water was
pouring out of the building. It's hard to tell how deep it got. I guess
the weather stripping was pretty good to allow the water to build up.

I'm still trying to decide whether to destroy the building or to gut it.
One wall actually is pushed off the floor, but the porch is holding it
tight.

Little by little I have been salvaging stuff. All clothing and any cloth
is trash. All books are trash, all furniture is trash. But I have been
saving CDs and DVDs. They need to be washed is all. And saving all tools
and metal stuff. I decided to see what I could do with the electronics.
Several transistorized radios work fine, except for the speakers. But it
appears the LCD stuff is trash. That GPS screen is touch screen and the
touch part no longer works, plus the longer it's been plugged in, the
more of the screen is turning black. That GPS was never worthwhile
anyhow, so I I dont much care. That scanner was nice though. I guess
I'll just have to go on ebay and find a replacement.

There are a few pices of tube gear. I have not plugged them in, because
I fear water in the transformers. I'll probably pop the tops off them
transformers and see how they look inside. There were also some
computers in there. Old ones that I really wont miss. But I found that
all computer motherboards and cards do survive floods. But the drives
are all trash. But I am not gonna waste time on them computers. I may
salvege a few of the cards and the RAM, and send the rest of them to the
recycler.



  #10   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 1,625
Default Saving LCD screens that were under water

We have a summer house that flooded some time ago (we are 8' up now), and in it were a number of electronic pieces including:

Soundcraftsman Tuner, with Backlit LCD screen
Dynaco PAT4
Dynaco ST120
Sony CD Player
Sony VCR

The speakers were above the flood waters.

All of the above traveled through our Bosch dishwasher with exactly 1/2 the normal amount of detergent. From there they went into a 150F gas-fired oven for four (4) hours. Tops off, guts exposed, but upside down.

Moving parts, slide-rails and so forth were lubricated before returning to service. Some belts were also replaced (with O-rings).

All are fine.

If the alternative is landfill, heroic measures are entirely appropriate.

Peter Wieck
Melrose Park, PA


  #11   Report Post  
Posted to sci.electronics.repair,sci.electronics.design
external usenet poster
 
Posts: 1,243
Default Saving LCD screens that were under water

On 6/7/2018 9:24 AM, Jeff Liebermann wrote:
On Thu, 07 Jun 2018 00:15:38 -0500, wrote:

I had some electronics in a storage building, which flooded. I figured
that most of it is junk, but I wiped it clean and put some of the stuff
outside in the sun to bake dry. So far, much of it works. But two
items, a GPS and a Police Scanner, both with LCD screens have very faint
screens. I kind of think the water affected the LCD screens.

Is there any way to get them LCD screens to work (other than replacing
them)?


No. LCD panels are not hermitically sealed. If it were sealed, the
glass would bulge when the panel becomes hot. There is a tiny hole,
usually near the bottom of the screen, to equalize the air pressure on
both sides of the glass. If you immerse the panel in cold water, the
air inside the glass screen will contract, causing a partial vacuum,
which will suck the water into the panel. If you remove the frame
from the panel, you can see the water inside the panel.

I had the bright idea of heating the panel to build up internal air
pressure and thus push the water out of the panel. That didn't work.
I also tried using a vacuum pump on the outside to help suck out the
water, but that also failed.


I'm surprised that the vacuum failed. Should pump down to the vapor
pressure of water and hang there until the water is gone before continuing
the pressure descent. That's as dry as you're ever gonna get it.
Even if it did get the water out, the LCD still might not work.

Best results were to attach something
that wicks water (cotton balls, rice, desiccant) at the hole, to suck
out the water via capillary action. Even so, I was only able to
extract a tiny amount of water, leaving most of it inside the panel.
When the price of panels dropped dramatically, I gave up on trying to
fix these.

The GPS and radio scanner probably have corrosion damaged PCB traces.
If you can find the damage and repair the traces, both can be fixed.


  #12   Report Post  
Posted to sci.electronics.repair,sci.electronics.design
external usenet poster
 
Posts: 4,045
Default Saving LCD screens that were under water

On Thu, 07 Jun 2018 13:15:07 -0700, mike wrote:

On 6/7/2018 9:24 AM, Jeff Liebermann wrote:
(...)
I had the bright idea of heating the panel to build up internal air
pressure and thus push the water out of the panel. That didn't work.
I also tried using a vacuum pump on the outside to help suck out the
water, but that also failed.


I'm surprised that the vacuum failed. Should pump down to the vapor
pressure of water and hang there until the water is gone before continuing
the pressure descent. That's as dry as you're ever gonna get it.


I agree. It should have worked. I still have all the equipment
(except the fish tank) and could probably try again. I see water and
chemical cleaner damaged laptop displays all the time. They usually
have a jagged area near the bottom of the screen that has turned dark
black and shows no image. Most of the damage comes from spray
cleaners used to clean the LCD display, where the cleaner or water was
allowed to run down the screen, under the bezel, and into the display.

I was using an Edwards E2M-1.0 2 stage rotary vacuum pump:
https://shop.edwardsvacuum.com/products/r1/list.aspx
It's been run well past its 30,000(?) hr major overhaul point and is
probably leaking around all the rubber vanes and seals. As I recall,
it went down to about 200 milliTorr and refused to go lower, probably
because of leaks in the reinforced fish aquarium I was using for a
test chamber. Water has a vapor pressure of 25 Torr (0.5 PSI), so
that should have easily sucked all the gas and water vapor out even
with all the leaks. I had hoped to see some boiling near the hole,
but didn't see any.

What I think might have happened is the air pressure equalization hole
got plugged up with a RTV used to seal the glass panel. The pressure
on the parallel glass plates might have compressed the RTV seal, which
then expanded sideways and closed the hole. Just a guess(tm).

Even if it did get the water out, the LCD still might not work.


Yes, but it was worth the risk. At the time, large LCD panels were
rather expensive. However, when I put everything back together, I
still had a 1/4" wide jagged black smear at the bottom of the screen
near both corners.

Incidentally, my "fix" for this customer was rather creative. I
flipped the monitor over by reversing the position on the VESA mount
and inverted the display using the Nvidia display control application.
It then had black areas near the top of the display, where there's
very little worth seeing. However, the customer could now see the
bottom of the screen, where the task bar and Start button reside.
Moving just the task bar to the top of the screen didn't work, because
the Start button was under the black blob and couldn't be seen.

--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
  #13   Report Post  
Posted to sci.electronics.repair,sci.electronics.design
external usenet poster
 
Posts: 1
Default Saving LCD screens that were under water

"Jeff Liebermann" wrote in message
...

On Thu, 07 Jun 2018 13:15:07 -0700, mike wrote:

On 6/7/2018 9:24 AM, Jeff Liebermann wrote:
(...)
I had the bright idea of heating the panel to build up internal air
pressure and thus push the water out of the panel. That didn't work.
I also tried using a vacuum pump on the outside to help suck out the
water, but that also failed.


I'm surprised that the vacuum failed. Should pump down to the vapor
pressure of water and hang there until the water is gone before continuing
the pressure descent. That's as dry as you're ever gonna get it.


I agree. It should have worked. I still have all the equipment
(except the fish tank) and could probably try again. I see water and
chemical cleaner damaged laptop displays all the time. They usually
have a jagged area near the bottom of the screen that has turned dark
black and shows no image. Most of the damage comes from spray
cleaners used to clean the LCD display, where the cleaner or water was
allowed to run down the screen, under the bezel, and into the display.

I was using an Edwards E2M-1.0 2 stage rotary vacuum pump:
https://shop.edwardsvacuum.com/products/r1/list.aspx
It's been run well past its 30,000(?) hr major overhaul point and is
probably leaking around all the rubber vanes and seals. As I recall,
it went down to about 200 milliTorr and refused to go lower, probably
because of leaks in the reinforced fish aquarium I was using for a
test chamber. Water has a vapor pressure of 25 Torr (0.5 PSI), so
that should have easily sucked all the gas and water vapor out even
with all the leaks. I had hoped to see some boiling near the hole,
but didn't see any.

What I think might have happened is the air pressure equalization hole
got plugged up with a RTV used to seal the glass panel. The pressure
on the parallel glass plates might have compressed the RTV seal, which
then expanded sideways and closed the hole. Just a guess(tm).

Even if it did get the water out, the LCD still might not work.


Yes, but it was worth the risk. At the time, large LCD panels were
rather expensive. However, when I put everything back together, I
still had a 1/4" wide jagged black smear at the bottom of the screen
near both corners.

Incidentally, my "fix" for this customer was rather creative. I
flipped the monitor over by reversing the position on the VESA mount
and inverted the display using the Nvidia display control application.
It then had black areas near the top of the display, where there's
very little worth seeing. However, the customer could now see the
bottom of the screen, where the task bar and Start button reside.
Moving just the task bar to the top of the screen didn't work, because
the Start button was under the black blob and couldn't be seen.

Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
================================================== =====

First, the water ran in the hole as liquid but you are trying to get it back
out as vapor which is going to be a much slower process. There is about a
1000 fold expansion in volume going from liquid to vapor, and the flow
conductance of the hole will be 2-10 times lower for vapor depending on the
pressure (for this case, using a pump with the liquid would be cheating
:-)). Second, depending on the size of the hole and the mass of the glass
at the hole and how much water there is and where the boiling and thus
evaporative cooling is occurring and lots of other things it is entirely
possible for the water to freeze as it boils inside the hole so the ice can
plug the hole. This stops the drying and the evaporative cooling as the ice
slowly warms back up by conduction from the mass of the LCD, melting the
ice, so it can boil again, then freeze and plug the hole, and round and
round it goes. The vacuum is also an insulator so the LCD will slowly cool
down and each melting cycle will be slower - venting to atmosphere every so
often can actually speed things up sometimes. With one tiny pinhole this
probably isn't an issue but if you are trying to dry something bulky like a
book a heat lamp and venting to melt the ice block occasionally really
helps. Of course, that assumes you aren't freeze drying something fragile
like a drug where you need the frozen matrix to prevent chemical damage.
Anyway, I think vacuum would work but it will be very slow. The
descriptions I've heard using dry rice talk to dry a wet cell phone talk
about a few days, and I bet the vacuum wouldn't be much faster to dry an
LCD.

--
Regards,
Carl Ijames


  #14   Report Post  
Posted to sci.electronics.repair,sci.electronics.design
external usenet poster
 
Posts: 1,243
Default Saving LCD screens that were under water

On 6/7/2018 4:32 PM, Jeff Liebermann wrote:
On Thu, 07 Jun 2018 13:15:07 -0700, mike wrote:

On 6/7/2018 9:24 AM, Jeff Liebermann wrote:
(...)
I had the bright idea of heating the panel to build up internal air
pressure and thus push the water out of the panel. That didn't work.
I also tried using a vacuum pump on the outside to help suck out the
water, but that also failed.


I'm surprised that the vacuum failed. Should pump down to the vapor
pressure of water and hang there until the water is gone before continuing
the pressure descent. That's as dry as you're ever gonna get it.


I agree. It should have worked. I still have all the equipment
(except the fish tank) and could probably try again. I see water and
chemical cleaner damaged laptop displays all the time. They usually
have a jagged area near the bottom of the screen that has turned dark
black and shows no image. Most of the damage comes from spray
cleaners used to clean the LCD display, where the cleaner or water was
allowed to run down the screen, under the bezel, and into the display.


In that case, I don't think there's anything you can do to fix it.
Once the water has invaded the pixel area, it's all over.

I was using an Edwards E2M-1.0 2 stage rotary vacuum pump:
https://shop.edwardsvacuum.com/products/r1/list.aspx
It's been run well past its 30,000(?) hr major overhaul point and is
probably leaking around all the rubber vanes and seals. As I recall,
it went down to about 200 milliTorr and refused to go lower, probably
because of leaks in the reinforced fish aquarium I was using for a
test chamber. Water has a vapor pressure of 25 Torr (0.5 PSI), so
that should have easily sucked all the gas and water vapor out even
with all the leaks. I had hoped to see some boiling near the hole,
but didn't see any.


I was experimenting with making heat pipes years ago. I don't remember
the numbers, but 0.5 PSI sounds WAY higher than I was trying.
As a test, I put the vacuum gauge right on the suction port of the pump.
It went down to where water was supposed to vaporize and stuck there
until I gave up. Reading about it suggested that you have to suck all
the water (and other contaminants) out of the pump oil before you can do
anything useful. They recommended FRESH oil for every evacuation.
I bought some pump oil, but never got around to trying it.

What I think might have happened is the air pressure equalization hole
got plugged up with a RTV used to seal the glass panel. The pressure
on the parallel glass plates might have compressed the RTV seal, which
then expanded sideways and closed the hole. Just a guess(tm).

Even if it did get the water out, the LCD still might not work.


Yes, but it was worth the risk. At the time, large LCD panels were
rather expensive. However, when I put everything back together, I
still had a 1/4" wide jagged black smear at the bottom of the screen
near both corners.

Incidentally, my "fix" for this customer was rather creative. I
flipped the monitor over by reversing the position on the VESA mount
and inverted the display using the Nvidia display control application.
It then had black areas near the top of the display, where there's
very little worth seeing. However, the customer could now see the
bottom of the screen, where the task bar and Start button reside.
Moving just the task bar to the top of the screen didn't work, because
the Start button was under the black blob and couldn't be seen.


  #15   Report Post  
Posted to sci.electronics.repair,sci.electronics.design
external usenet poster
 
Posts: 4,045
Default Saving LCD screens that were under water

On Thu, 07 Jun 2018 22:13:46 -0700, mike wrote:

On 6/7/2018 4:32 PM, Jeff Liebermann wrote:

(...)

In that case, I don't think there's anything you can do to fix it.
Once the water has invaded the pixel area, it's all over.


Yep. The secret to engineering is knowing when to give up.

I was using an Edwards E2M-1.0 2 stage rotary vacuum pump:
https://shop.edwardsvacuum.com/products/r1/list.aspx
It's been run well past its 30,000(?) hr major overhaul point and is
probably leaking around all the rubber vanes and seals. As I recall,
it went down to about 200 milliTorr and refused to go lower, probably
because of leaks in the reinforced fish aquarium I was using for a
test chamber. Water has a vapor pressure of 25 Torr (0.5 PSI), so
that should have easily sucked all the gas and water vapor out even
with all the leaks. I had hoped to see some boiling near the hole,
but didn't see any.


I was experimenting with making heat pipes years ago. I don't remember
the numbers, but 0.5 PSI sounds WAY higher than I was trying.


Vapor pressure of water in Torr:
http://www.wiredchemist.com/chemistry/data/vapor-pressure
and in PSI:
http://www.pumpworld.com/vapor-pressure-chart.htm
25 Torr or 0.5 PSI look right.

As a test, I put the vacuum gauge right on the suction port of the pump.
It went down to where water was supposed to vaporize and stuck there
until I gave up. Reading about it suggested that you have to suck all
the water (and other contaminants) out of the pump oil before you can do
anything useful. They recommended FRESH oil for every evacuation.
I bought some pump oil, but never got around to trying it.


That could have been my problem. At the time, all I had was the oil
that was in the vacuum pump when I bought it used. It probably was
rather dirty and likely contaminated with some water from
condensation. Looking at the pump through the oil level sight glass,
it looks dirty. New oil is about $30/gallon. I was eventually going
to buy the o-ring and basic rebuild kit, at which time I would buy
some new oil. However, I was getting a usable vacuum, so I didn't
bother.


--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558


  #16   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 635
Default Saving LCD screens that were under water

On 06/07/2018 03:31 PM, wrote:
On Thu, 7 Jun 2018 09:38:48 -0400, Phil Hobbs
wrote:

On 06/07/2018 09:11 AM, Fox's Mercantile wrote:
On 6/7/18 7:32 AM,
wrote:
On Thursday, June 7, 2018 at 8:01:54 AM UTC-4, Fox's Mercantile wrote:

Throw the stuff out and spend your time fixing the roof.

That IS rather ironic coming from you - ;-)

My roof leaks. I have enough sense to have tarps protecting stuff.



Could have been surface water. My back yard occasionally floods
too--it's a very pleasant place but is a former pond bottom.

Cheers

Phil Hobbs
(Who has a deep affection for his storm drain)


It was not the roof, a water pipe broke the main brass valve. The water
was shut off at that valve and there was heat tape on the valve and the
pipe below that valve, but that heat tape must have failed. Water was
pouring out of the building. It's hard to tell how deep it got. I guess
the weather stripping was pretty good to allow the water to build up.

I'm still trying to decide whether to destroy the building or to gut it.
One wall actually is pushed off the floor, but the porch is holding it
tight.

Little by little I have been salvaging stuff. All clothing and any cloth
is trash. All books are trash, all furniture is trash. But I have been
saving CDs and DVDs. They need to be washed is all. And saving all tools
and metal stuff. I decided to see what I could do with the electronics.
Several transistorized radios work fine, except for the speakers. But it
appears the LCD stuff is trash. That GPS screen is touch screen and the
touch part no longer works, plus the longer it's been plugged in, the
more of the screen is turning black. That GPS was never worthwhile
anyhow, so I I dont much care. That scanner was nice though. I guess
I'll just have to go on ebay and find a replacement.

There are a few pices of tube gear. I have not plugged them in, because
I fear water in the transformers. I'll probably pop the tops off them
transformers and see how they look inside. There were also some
computers in there. Old ones that I really wont miss. But I found that
all computer motherboards and cards do survive floods. But the drives
are all trash. But I am not gonna waste time on them computers. I may
salvege a few of the cards and the RAM, and send the rest of them to the
recycler.



Blech. Sorry to hear that.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net
  #17   Report Post  
Posted to sci.electronics.repair,sci.electronics.design
external usenet poster
 
Posts: 1,243
Default Saving LCD screens that were under water

On 6/7/2018 10:46 PM, Jeff Liebermann wrote:
On Thu, 07 Jun 2018 22:13:46 -0700, mike wrote:

On 6/7/2018 4:32 PM, Jeff Liebermann wrote:

(...)

In that case, I don't think there's anything you can do to fix it.
Once the water has invaded the pixel area, it's all over.


Yep. The secret to engineering is knowing when to give up.

I was using an Edwards E2M-1.0 2 stage rotary vacuum pump:
https://shop.edwardsvacuum.com/products/r1/list.aspx
It's been run well past its 30,000(?) hr major overhaul point and is
probably leaking around all the rubber vanes and seals. As I recall,
it went down to about 200 milliTorr and refused to go lower, probably
because of leaks in the reinforced fish aquarium I was using for a
test chamber. Water has a vapor pressure of 25 Torr (0.5 PSI), so
that should have easily sucked all the gas and water vapor out even
with all the leaks. I had hoped to see some boiling near the hole,
but didn't see any.


I was experimenting with making heat pipes years ago. I don't remember
the numbers, but 0.5 PSI sounds WAY higher than I was trying.


Vapor pressure of water in Torr:
http://www.wiredchemist.com/chemistry/data/vapor-pressure
and in PSI:
http://www.pumpworld.com/vapor-pressure-chart.htm
25 Torr or 0.5 PSI look right.


If my google is right, HVAC systems are typically evacuated below
500 microns to get all the water out. That's more like 0.5 Torr.
My memory is vague, but somewhere under 2000 microns was where
the pressure stopped decreasing due to water contamination.
With even the slightest
leak in the system, I couldn't get there.

As a test, I put the vacuum gauge right on the suction port of the pump.
It went down to where water was supposed to vaporize and stuck there
until I gave up. Reading about it suggested that you have to suck all
the water (and other contaminants) out of the pump oil before you can do
anything useful. They recommended FRESH oil for every evacuation.
I bought some pump oil, but never got around to trying it.


That could have been my problem. At the time, all I had was the oil
that was in the vacuum pump when I bought it used. It probably was
rather dirty and likely contaminated with some water from
condensation. Looking at the pump through the oil level sight glass,
it looks dirty. New oil is about $30/gallon. I was eventually going
to buy the o-ring and basic rebuild kit, at which time I would buy
some new oil. However, I was getting a usable vacuum, so I didn't
bother.



  #18   Report Post  
Posted to sci.electronics.repair,sci.electronics.design
external usenet poster
 
Posts: 4,045
Default Saving LCD screens that were under water

On Sat, 09 Jun 2018 05:08:37 -0700, mike wrote:

On 6/7/2018 10:46 PM, Jeff Liebermann wrote:
On Thu, 07 Jun 2018 22:13:46 -0700, mike wrote:

On 6/7/2018 4:32 PM, Jeff Liebermann wrote:

(...)

In that case, I don't think there's anything you can do to fix it.
Once the water has invaded the pixel area, it's all over.


Yep. The secret to engineering is knowing when to give up.

I was using an Edwards E2M-1.0 2 stage rotary vacuum pump:
https://shop.edwardsvacuum.com/products/r1/list.aspx
It's been run well past its 30,000(?) hr major overhaul point and is
probably leaking around all the rubber vanes and seals. As I recall,
it went down to about 200 milliTorr and refused to go lower, probably
because of leaks in the reinforced fish aquarium I was using for a
test chamber. Water has a vapor pressure of 25 Torr (0.5 PSI), so
that should have easily sucked all the gas and water vapor out even
with all the leaks. I had hoped to see some boiling near the hole,
but didn't see any.

I was experimenting with making heat pipes years ago. I don't remember
the numbers, but 0.5 PSI sounds WAY higher than I was trying.


Vapor pressure of water in Torr:
http://www.wiredchemist.com/chemistry/data/vapor-pressure
and in PSI:
http://www.pumpworld.com/vapor-pressure-chart.htm
25 Torr or 0.5 PSI look right.


If my google is right, HVAC systems are typically evacuated below
500 microns to get all the water out. That's more like 0.5 Torr.


The point at which water starts to boil at room temp is 20,300 microns
of Hg or 0.393 PSIA or about 20 Torr. Presumably, that's when the
water starts to turn to vapor which can the be removed by the pump.
However, at this pressure, it will take forever, so a much lower
vacuum is probably more practical. Whether it needs 40x more, I don't
know.

My memory is vague, but somewhere under 2000 microns was where
the pressure stopped decreasing due to water contamination.
With even the slightest
leak in the system, I couldn't get there.


When I filled my aquarium with water, applied a vacuum, and looked for
bubbles, in order to check for leaks, I found quite a few. These were
duly plugged with RTV. I had no trouble going down to what I thought
was 200 milliTorr (0.00386 PSI), but now I'm not so sure. I have the
vacuum pump and gauge and might be able to try again, but not for a
while. I would need to build a new vacuum test chamber and don't have
the time, bench space, fresh vacuum oil, fittings, rebuild kit, etc.

As a test, I put the vacuum gauge right on the suction port of the pump.
It went down to where water was supposed to vaporize and stuck there
until I gave up. Reading about it suggested that you have to suck all
the water (and other contaminants) out of the pump oil before you can do
anything useful. They recommended FRESH oil for every evacuation.
I bought some pump oil, but never got around to trying it.


That could have been my problem. At the time, all I had was the oil
that was in the vacuum pump when I bought it used. It probably was
rather dirty and likely contaminated with some water from
condensation. Looking at the pump through the oil level sight glass,
it looks dirty. New oil is about $30/gallon. I was eventually going
to buy the o-ring and basic rebuild kit, at which time I would buy
some new oil. However, I was getting a usable vacuum, so I didn't
bother.


--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
  #19   Report Post  
Posted to sci.electronics.repair
external usenet poster
 
Posts: 411
Default Saving LCD screens that were under water

On Fri, 8 Jun 2018 10:13:54 -0400, Phil Hobbs
wrote:

There are a few pices of tube gear. I have not plugged them in, because
I fear water in the transformers. I'll probably pop the tops off them
transformers and see how they look inside. There were also some
computers in there. Old ones that I really wont miss. But I found that
all computer motherboards and cards do survive floods. But the drives
are all trash. But I am not gonna waste time on them computers. I may
salvege a few of the cards and the RAM, and send the rest of them to the
recycler.



Blech. Sorry to hear that.

Cheers

Phil Hobbs


That GPS with touch screen was viewable at first. Cloudy, but I could
still see the screen. The touch part did not work though. I left it
turned on, charged the battery and what started as small black blobs on
the screen, turned into one huge black blob in the middle of the screen.
I'd say that 2/3 of the screen is now black. All I see is light around
the edges, and it's just light, nothing usable to read or see. It's kind
of like it's self destructing. I even layed it on my dashboard in my car
and let the sun overheat it. I never liked that thing anyhow, so I wont
miss it. I've only messed with it to see what happens to a LCD screen
that was under water. Now I know!!!

On the other hand, almost all radios that were flooded do still work. I
just made sure they were well dried before plugging them in. Of course
they all need new speakers, but thats an easy fix.

Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
where do you get replacement lcd screens Pinballer Electronics Repair 5 April 1st 07 12:15 AM
Bugs inside LCD screens n cook Electronics Repair 3 November 29th 06 10:23 AM
Cost of replacing LCD screens [email protected] Electronics Repair 4 November 1st 06 04:53 AM
water cooler, water coolers, water dispenser, water dispensers,bottleless water cooler,bottleless water coolers,bottleless water dispenser,bottleless water dispensers water coolers UK diy 3 January 5th 06 08:23 PM
nec lcd monitor screens bigworm Electronics Repair 1 November 3rd 05 06:03 PM


All times are GMT +1. The time now is 10:56 PM.

Powered by vBulletin® Copyright ©2000 - 2023, Jelsoft Enterprises Ltd.
Copyright 2004-2023 DIYbanter.
The comments are property of their posters.
 

About Us

"It's about DIY & home improvement"