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#2167381 - 02/10/11 03:27 PM Took Apart Digital Tire Pressure Gauge - Fail!
George7941 Offline


Registered: 05/10/05
Posts: 1466
Loc: Toronto, Canada
So, my Accutire gauge, after nine years, displays L. It came with a ten year warranty, including the battery. I e-mailed Accutire about getting the battery replaced but they did not reply.

I took the gauge apart to replace the CR2032 battery. Here are some pictures










I put it all back together but now it will only display 01.0, no matter what the pressure is. It looks like I will be buying another gauge.

They have a weird way of mounting and connecting the LED display. The black strip, just above the display, in the first picture, is the contact strip that connects the display to the circuit board. What is strange is that I see no corresponding contacts on the back of the display. In the third picture, you can see the row of contacts on which this strip sits. Anyone know how this works?
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2006 GMC Sierra 4.3l, NV3500,G80 locker rear, Formula Shell Synthetic 5W30, Wix 51036, Dexcool.
1987 BMW R80

Staying out of the right lane a lot.

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#2167491 - 02/10/11 05:16 PM Re: Took Apart Digital Tire Pressure Gauge - Fail! [Re: George7941]
Steve S Offline


Registered: 01/20/03
Posts: 18449
Loc: East of IGO
Been there done that but not on a tire gauge.
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#2167522 - 02/10/11 05:56 PM Re: Took Apart Digital Tire Pressure Gauge - Fail! [Re: George7941]
Eddie Offline


Registered: 12/07/03
Posts: 6695
Loc: Florida, Cape Coral
Did you ground yourself before taking it apart? Static shock with ruin the components on the board.
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#2167612 - 02/10/11 07:50 PM Re: Took Apart Digital Tire Pressure Gauge - Fail! [Re: George7941]
Vizzy Offline


Registered: 04/26/09
Posts: 1183
Loc: Canada
Originally Posted By: George7941
So, my Accutire gauge, after nine years, displays L. It came with a ten year warranty, including the battery. I e-mailed Accutire about getting the battery replaced but they did not reply.

?


Why didn't you call them or e mail again?

I would have. If it has a 10 yr warranty you should have made them honor it.


Go ahead and put the thing back together with the old battery in it as well. Contact them again and send the old one back to them.

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#2167655 - 02/10/11 08:47 PM Re: Took Apart Digital Tire Pressure Gauge - Fail! [Re: Vizzy]
George7941 Offline


Registered: 05/10/05
Posts: 1466
Loc: Toronto, Canada
I did not ground myself, so it is possible that some static damaged some component. I will be more careful next time.

It is going to be a hassle getting them to change the battery since they have changed the battery warranty on their current products. I have the original package on which it explicitly states that the battery has a lifetime warranty


Since I paid less than ten dollars for it and shipping it to them from Canada will cost me a few dollars, I am not going to go thru the trouble of getting them to honor the warranty.

I am still curious as to how the strip makes contact with the display module.
_________________________
2006 GMC Sierra 4.3l, NV3500,G80 locker rear, Formula Shell Synthetic 5W30, Wix 51036, Dexcool.
1987 BMW R80

Staying out of the right lane a lot.

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#2167832 - 02/11/11 04:13 AM Re: Took Apart Digital Tire Pressure Gauge - Fail! [Re: George7941]
Rick in PA Offline


Registered: 01/04/03
Posts: 2125
Loc: Southeastern, PA
Not sure if the contact strip is like this, but it's one interesting low cost type that I have encountered. They take very thin alternating layers of conductive and non-conductive rubber and bond them together in a many, many layer sandwich. Then they dice the sandwich across the layers to make a strip that has a large number of conductors perpendicular to the strip. The layers have to be smaller than the contact pitch on the circuit board. Then they just lay the strip across the contacts on one circuit board and press the contacts of the second circuit board to the rubber sandwich. The edgewise conductive rubber layers make contact between the circuit boards. It's a low cost method of connecting circuit boards for low power applications such as driving an LCD.
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#2167935 - 02/11/11 08:11 AM Re: Took Apart Digital Tire Pressure Gauge - Fail! [Re: George7941]
George7941 Offline


Registered: 05/10/05
Posts: 1466
Loc: Toronto, Canada
That is it! The strip is made of many (maybe 50) layers of rubber.

What is still puzzling is that there are no visible contacts on the LCD module.



The white rectangle is the back of the LCD and it is recessed inside the clear rigid plastic frame. The strip is mounted on the one of the long edges of the rectangle and I don't see what it is making contact with.
_________________________
2006 GMC Sierra 4.3l, NV3500,G80 locker rear, Formula Shell Synthetic 5W30, Wix 51036, Dexcool.
1987 BMW R80

Staying out of the right lane a lot.

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#2168098 - 02/11/11 11:12 AM Re: Took Apart Digital Tire Pressure Gauge - Fail! [Re: George7941]
ARB1977 Offline


Registered: 06/12/05
Posts: 4478
Loc: North Texas
Ten years for ten dollar gauge...not bad. Just go get another one.
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#2168656 - 02/11/11 09:47 PM Re: Took Apart Digital Tire Pressure Gauge - Fail! [Re: George7941]
wapacz Offline


Registered: 11/21/05
Posts: 929
Loc: MI
When you get L it mean the internal battery is dead from my understanding. The way I figure it is that the internal battery keeps some form of calibration for the sensor. When it dies the calibration is lost and it only displays 1.

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#2168813 - 02/12/11 04:31 AM Re: Took Apart Digital Tire Pressure Gauge - Fail! [Re: George7941]
Rick in PA Offline


Registered: 01/04/03
Posts: 2125
Loc: Southeastern, PA
Originally Posted By: George7941
That is it! The strip is made of many (maybe 50) layers of rubber.

What is still puzzling is that there are no visible contacts on the LCD module.



The white rectangle is the back of the LCD and it is recessed inside the clear rigid plastic frame. The strip is mounted on the one of the long edges of the rectangle and I don't see what it is making contact with.


Not sure what they're using for contacts, but I have a guess. They may have to route the electrical charges over the clear LCD display, so they might be using something that's clear and conductive. Years ago, I came across tin-oxide coated glass. It was clear (maybe a bit of tint) but the surface was very conductive. You could measure the surface resistance with a standard multi-meter. It was an interesting material. I'll bet there's contacts there, they're just not visible.
_________________________
"Heat is your friend."

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#2169944 - 02/13/11 11:43 AM Re: Took Apart Digital Tire Pressure Gauge - Fail! [Re: Rick in PA]
George7941 Offline


Registered: 05/10/05
Posts: 1466
Loc: Toronto, Canada
Right again! I took a close look at the LCD module and if you look directly at the transparent edge of the module, nothing is visible but, if you look at the edge at a very shallow angle, the strips become visible. They match (spacing and width) the contacts on the printed circuit board.
_________________________
2006 GMC Sierra 4.3l, NV3500,G80 locker rear, Formula Shell Synthetic 5W30, Wix 51036, Dexcool.
1987 BMW R80

Staying out of the right lane a lot.

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