OT:Kenmore range display diming?

[Hammy]

I have a Kenmore flat-top range that's about 7 years old. The LCD
display is diming almost to the point were its unreadable. The clock
portion of the display is fine it's just the temperature setting that's
almost invisible at the top left of the display it's in a different
color as well orange where as the clock part is green.

I was wondering if anyone ever took one apart. Do they have a simple
analog POT for contrast adjusting or is it a digital one or fixed
value? Is there any other reason this would happen? I have cleaned it
so its not dirt or grime.

I was looking at control boards and they are $200 plus so before I go
that route I thought I would check here.

 

[Hammy]

I have a Kenmore flat-top range that's about 7 years old. The LCD
display is diming almost to the point were its unreadable. The
clock portion of the display is fine it's just the temperature
setting that's almost invisible at the top left of the display
it's in a different color as well orange where as the clock part
is green.

Whoops its a seven segment display not an LCD.

 

[Joerg]

Whoops its a seven segment display not an LCD.

LED? Then the driver chip may be dying. LEDs lose brightness but not
this quickly. According to Murphy's law it will be either unobtanium or
impossible to unsolder.

 

[Spehro Pefhany]

Whoops its a seven segment display not an LCD.

Almost certainly a Vacuum Flourescent Display (VFD). I'd guess a power
supply electrolyic capacity is dying/dead, but I could be wrong.

Kenmore is pretty good with replacement parts, have you checked out
the price of a replacement module?


Best regards,
Spehro Pefhany

 

[Joerg]

Is it an LED, or a VFD?

VFDs do tend to dim out over time, just like a CRT does (and, I
believe, for similar reasons).

If they do you can increase the filament voltage a bit. At some point
you might see the wires glow very faintly but that is still better than
shelling out big bucks for a replacement module.

If clock and temp display are inside the same VFD I doubt it's fading
though.

 

[Joerg]

We recently bought a new gas range for our cabin, and I was determined
to have one with no electronics. ...

That was a smart decision.

... That costs 3x to 10x more than one
that has electronics. Only high-end ranges are available with no
electronics. They all do have electronic ignitors, but they don't need
the ignitor to work.

3x to 10x? Nah. Most have a clock and timer built in but many supposedly
work with the power disconnected if you don't need those features. Not
100% sure but I believe this series does:

http://www.homeeverything.com/web/sitefiles/product.asp?sku=22617&ref=cBizRate

Of course, if you want stainless steel restaurant grade stuff, different
thing.

 

[Joerg]

We got this NXR thing

http://www.durocorp.com/products/nrg3001/

for $2K, delivered in Truckee. It's assembled in California from
Chinese stainless sheet metal and German burners. It's like a Wolf or
a Viking at half the price.

Looks a lot less bland than the usual Aunt Bee style ranges. But twice
the price of a regular range just for a cabin is still a bit steep. OTOH
I guess your wife would like it to look nice.

The real top notch brands hold up pretty good but most of their parts
are custom. Then when the series is obsoleted ... poof ... no spare
parts. Our kitchen has Thermador gear, restaurant grade, still works
after 40 years with just minor repairs. But there are some not so nice
details, for example we have to guesstimate the temperature on one of
the ovens because the Fahrenheit lettering has rubbed off. Can't get
such knobs anywhere and when something major goes that might be the end
for the range or the ovens.

 

[Rich Grise]

We recently bought a new gas range for our cabin, and I was determined to
have one with no electronics. That costs 3x to 10x more than one that has
electronics. Only high-end ranges are available with no electronics. They
all do have electronic ignitors, but they don't need the ignitor to work.

You should have checked at Goodwill, the Salivation[SIC] army, or
various large thrift shops and got an old one that somebody donated when
Grandma passed away.

Cheers!
Rich

 

[Hammy]

Almost certainly a Vacuum Flourescent Display (VFD). I'd guess a
power supply electrolyic capacity is dying/dead, but I could be
wrong.

That is one of the possibilities I found while googling. I think your
right its a VFD. I'll try replaceing the caps either tonight or on the
weekend.

Kenmore is pretty good with replacement parts, have you checked
out the price of a replacement module?

I'm going to call sears and see today. I did find similiar ones for
kenmores while googling and they were $165 to 200 plus. Over 200 and I
might as well buy a new range.

 

[Hammy]

LED? Then the driver chip may be dying. LEDs lose brightness but
not this quickly. According to Murphy's law it will be either
unobtanium or impossible to unsolder.

I thnk Spehro right after looking at some pics its a VFD. Some googling
shows its pretty common with even the newer models The recomended fixes
or either the caps or replace the whole control board.

I'll try the caps first if a board is over $200 I guess I'll be looking
for a new range their are some good sales on now. Like John pointed out
I dont think you can even get a range anymore without a similiar type
display. I think they call it built-in obsolescence.

My sister got my parents old inglis 20+ years before it finally died no
electronics of course.

 

[Spehro Pefhany]

That is one of the possibilities I found while googling. I think your
right its a VFD. I'll try replaceing the caps either tonight or on the
weekend.



I'm going to call sears and see today. I did find similiar ones for
kenmores while googling and they were $165 to 200 plus. Over 200 and I
might as well buy a new range.

Once you get a part number, try the US discount parts suppliers.. I
was able to get a replacement ice maker water valve kit for a
refrigerator for a really good price and even a whole ice maker would
cost less than a service call to replace some trivial bit.

 

[Joerg]

I thnk Spehro right after looking at some pics its a VFD. Some googling
shows its pretty common with even the newer models The recomended fixes
or either the caps or replace the whole control board.

I'll try the caps first if a board is over $200 I guess I'll be looking
for a new range their are some good sales on now. Like John pointed out
I dont think you can even get a range anymore without a similiar type
display. I think they call it built-in obsolescence.

Yes, but if you buy smartly you can have one where it doesn't matter
whether the display works and the range will keep working.

My sister got my parents old inglis 20+ years before it finally died no
electronics of course.

Isn't that Whirlpool now?

 

[Hammy]

[snip]

Once you get a part number, try the US discount parts suppliers..
I was able to get a replacement ice maker water valve kit for a
refrigerator for a really good price and even a whole ice maker
would cost less than a service call to replace some trivial bit.

Well I just found out the range was purchased in 98! We got it off
my girlfriends parents it looked brand new when they gave it to us
about 3 years ago,still does. I just figured about 7 years old.

I found that out after talking with sears. I also found out they
dont carry parts for appliances beyond 10 years? The guy couldnt
even give me a part number for the display/ control board.

The Oven and everything works fine its just getting next to
impossible to read the oven temperature setting makeing it pretty
useless. Its a pretty decent flat top unit.

I'll pull the whole board out maybe tonight and have a look at it
for anything obvious at least change the caps while its out as well;
see if that helps.

 

[hamilton]

I've had pretty good luck here...

http://www.repairclinic.com/

...Jim Thompson

Thanks Jim, this is just what I needed.


hamilton

 

[JW]

Yup, that reference is what I recalled... that VFDs use filament-based
electron emission, to cause phosphors to fluoresce. They aren't all
that different from CRTs in that regard. I did recall they were prone
to aging due to filament wear-out (less emission) and apparently they
can suffer from phosphor wear-out as well.

From all the equipment I've worked on, it's the phosphor that burns out.

 

[Joerg]

http://en.wikipedia.org/wiki/Vacuum_fluorescent_display#Design

Yup, that reference is what I recalled... that VFDs use filament-based
electron emission, to cause phosphors to fluoresce. They aren't all
that different from CRTs in that regard. I did recall they were prone
to aging due to filament wear-out (less emission) and apparently they
can suffer from phosphor wear-out as well.
[/QUOTE]

The filament usually doesn't wear out. It's like the filament in a light
bulb except that it isn't even driven into a red glow so it'll usually
live forever (unlike the phosphor). When the phosphor gets tired you can
increase the filament voltage a bit. At some point the filament strings
start to glow and you'll see several faint dark red lines across the
display. That causes more electrons to be emitted, more brightness. But
the filament must be driven from an AC source, otherwise there can be
uneven brightness across the display, especially if it isn't very highly
muxed.

[...]

 

[ehsjr]

Yup, that reference is what I recalled... that VFDs use filament-based
electron emission, to cause phosphors to fluoresce. They aren't all
that different from CRTs in that regard. I did recall they were prone
to aging due to filament wear-out (less emission) and apparently they
can suffer from phosphor wear-out as well.

The filament usually doesn't wear out. It's like the filament in a light
bulb except that it isn't even driven into a red glow so it'll usually
live forever (unlike the phosphor). When the phosphor gets tired you can
increase the filament voltage a bit. At some point the filament strings
start to glow and you'll see several faint dark red lines across the
display. That causes more electrons to be emitted, more brightness. But
the filament must be driven from an AC source, otherwise there can be
uneven brightness across the display, especially if it isn't very highly
muxed.

[...]

Couldn't he just take it down to the corner drug store and use their
tube tester to see if it's weak? Of course, he would need a flux
capacitor ...

Ed

 

[Joerg]

VFDs do tend to dim out over time, just like a CRT does (and, I
believe, for similar reasons).

Yeah, it's called age... but not really a whole lot more than that is
similar other then that both are glass encapsulated devices.

A CRT may /will exhibit phosphor burn, not just at specific hard
spots, but homogenously across the surface over time and use as well.

The little tube is, IIRC, a gas filled device? There are a couple
variants (theorange and the blue variety), but certainly no electrons
cast against phosphors.

http://en.wikipedia.org/wiki/Vacuum_fluorescent_display#Design

Yup, that reference is what I recalled... that VFDs use filament-based
electron emission, to cause phosphors to fluoresce. They aren't all
that different from CRTs in that regard. I did recall they were prone
to aging due to filament wear-out (less emission) and apparently they
can suffer from phosphor wear-out as well.

The filament usually doesn't wear out. It's like the filament in a light
bulb except that it isn't even driven into a red glow so it'll usually
live forever (unlike the phosphor). When the phosphor gets tired you can
increase the filament voltage a bit. At some point the filament strings
start to glow and you'll see several faint dark red lines across the
display. That causes more electrons to be emitted, more brightness. But
the filament must be driven from an AC source, otherwise there can be
uneven brightness across the display, especially if it isn't very highly
muxed.

[...]

Couldn't he just take it down to the corner drug store and use their
tube tester to see if it's weak? Of course, he would need a flux
capacitor ...

And a time machine. Plus probably a DeSoto Club Coupe if it is a few
blocks away.

 

[Spehro Pefhany]

[1] except that NORITAKE has EOLd the glass. We just did a PC board
that uses an Atmel processor and an LCD, as a drop-in for the old VF
display board. It intercepts the SPI 16-segment+grid drive scan,
converts back to ASCII, and drives the LCD. Nuisance, but avoids
bashing the code on a bunch of products. Pity... the VFs looked great.

Did you check teh competition?
http://www.maxim-ic.com/app-notes/index.mvp/id/1154

Noritake used to be great- local office, great service etc. 8-(

 

[Joerg]

VFDs do tend to dim out over time, just like a CRT does (and, I
believe, for similar reasons).
Yeah, it's called age... but not really a whole lot more than that is
similar other then that both are glass encapsulated devices.

A CRT may /will exhibit phosphor burn, not just at specific hard
spots, but homogenously across the surface over time and use as well.

The little tube is, IIRC, a gas filled device? There are a couple
variants (theorange and the blue variety), but certainly no electrons
cast against phosphors.
http://en.wikipedia.org/wiki/Vacuum_fluorescent_display#Design
Yup, that reference is what I recalled... that VFDs use filament-based
electron emission, to cause phosphors to fluoresce. They aren't all
that different from CRTs in that regard. I did recall they were prone
to aging due to filament wear-out (less emission) and apparently they
can suffer from phosphor wear-out as well.

The filament usually doesn't wear out. It's like the filament in a light
bulb except that it isn't even driven into a red glow so it'll usually
live forever (unlike the phosphor). When the phosphor gets tired you can
increase the filament voltage a bit. At some point the filament strings
start to glow and you'll see several faint dark red lines across the
display. That causes more electrons to be emitted, more brightness. But
the filament must be driven from an AC source, otherwise there can be
uneven brightness across the display, especially if it isn't very highly
muxed.

[...]

We use 16-segment VFs in several of our products [1]. Most of these
are powered up 24/7. After 10 years or more of operation, they look
fine. Lots of clocks and microwave ovens and DVD players use VFs and
they seem to hold up very well.

We used DC filament drive, 24 volts on the grids/anodes, and it looked
fine.

24V non-muxed? That's a lot, then you should be able to read the numbers
from Sutro Tower

DC on the filaments is probably ok but if you look closely you'll
probably see a slight brightness variance from left to right. IOW, the
display sees 2-3V or whatever you filament voltage is less on one side.
This is why people either drive it switch-mode or use a 60Hz transformer
tap if there is one.

John

[1] except that NORITAKE has EOLd the glass. We just did a PC board
that uses an Atmel processor and an LCD, as a drop-in for the old VF
display board. It intercepts the SPI 16-segment+grid drive scan,
converts back to ASCII, and drives the LCD. Nuisance, but avoids
bashing the code on a bunch of products. Pity... the VFs looked great.

That is sad. VFDs look so much nicer, don't have a reading angle problem
and are just plain easier to read. Very much so for people who need to
wear reading glasses. But VFDs are power hogs because of the filament.