Hey folks,
My car (99 cutless) has display lamps out. They are
in the Fan speed , hot/cold and air direction switches module below
the radio. When its dark have the display doesn't light up. I took it
apart and found four little lamps with a blue piece of plastic over
the lamp, soldered to a circuit board. Only one of the four lamps was
working. Is it feasible to solder in new lamps and if yes, where could
I find these lamps? thanks for any help!!

I'm assuming the replacement part from GM is a horrendously expensive
PCB assembly.. But just out of curiosity, are you sure they're soldered
in? Sometimes they solder two posts to the board, and stick the lamp in
a little rubber tube which is shoved over the posts. You can remove the
lamp by pulling it loose.

Otherwise, I'm sure you can find something. Have you checked
Radioshack? If they can't help you can probably find them at Digi-Key.
Anything that will fit in the space will work. You might even consider
replacing them with solid-state lamps so you don't have to do this
again in 5 years.

harold balls wrote:
Hey folks,
My car (99 cutless) has display lamps out. They are
in the Fan speed , hot/cold and air direction switches module below
the radio. When its dark have the display doesn't light up. I took it
apart and found four little lamps with a blue piece of plastic over
the lamp, soldered to a circuit board. Only one of the four lamps was
working. Is it feasible to solder in new lamps and if yes, where could
I find these lamps? thanks for any help!!

First, you have to ID the type of lamps. If there absolutely not
socketed in some form, you probably have a fuse type or
a grain of wheat type. The fuse type look like a automotive fuse
with a metal cap on both ends. The grain of wheat have small lead wires
(some insulated, some not) coming out of one end of the glass bulb
directly. The grain of what bulbs come in different sizes, voltages and
current ratings. I assume your bulbs are 12 volts, but sometimes you
can find two 6 volt in series in some applications.
You might try looking at MCM electronics.

Some suggested solid state replacements. The problem there is a straight
LED runs on 2 to 3 volts or so and would need a dropping resistor to
be used in this application. Impossible? NO. But you would have to have
someone who really knew what they were doing to pull it off.

Depending on the size, you may find some small socketed bulbs used for
dash/IP lights and pull the leads straight and try to solder them in.
This will only work for the type of bulb that does not use a metal
socket and as the wires on wither side of the glass base.
Poke around a well equipped auto supply house and see what types
they got.

Bob

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In article ,
Bob Urz wrote:
Some suggested solid state replacements. The problem there is a straight
LED runs on 2 to 3 volts or so and would need a dropping resistor to
be used in this application. Impossible? NO. But you would have to have
someone who really knew what they were doing to pull it off.

They're actually current rather than voltage driven.

A 1000 ohm resistor in series with a standard LED will be fine for this
app.

--
*Real women don't have hot flashes, they have power surges.

Dave Plowman London SW
To e-mail, change noise into sound.

On Sat, 15 Oct 2005 16:17:56 +0100, "Dave Plowman (News)"
wrote:

In article ,
Bob Urz wrote:
Some suggested solid state replacements. The problem there is a straight
LED runs on 2 to 3 volts or so and would need a dropping resistor to
be used in this application. Impossible? NO. But you would have to have
someone who really knew what they were doing to pull it off.

They're actually current rather than voltage driven.

A 1000 ohm resistor in series with a standard LED will be fine for this
app.

Hey fellows,
Thanks for reply's . The lamp is soldered in because I
unsoldered it and took it out. Bob, I think your right, it is a grain
of wheat type lamp less the leads. Radio shack didn't have anything.
i will try those places that were suggested. Once more thanks for the
help!!

"harold balls" wrote in message
...
Hey folks,
My car (99 cutless) has display lamps out. They are
in the Fan speed , hot/cold and air direction switches module below
the radio. When its dark have the display doesn't light up. I took it
apart and found four little lamps with a blue piece of plastic over
the lamp, soldered to a circuit board. Only one of the four lamps was
working. Is it feasible to solder in new lamps and if yes, where could
I find these lamps? thanks for any help!!

Yes, they're called grain of wheat lamps, if you do a google search you may
find some places that sell them, if you get stuck I'll see what I can find.
You'll want to check and see how they're wired, I've seen 12v lamps in
parallel and I've seen pairs of 6v lamps in series. Personally I try to
replace these with LEDs whenever possible, you need to find room for the
current limiting resistor if you go that route but for all practical
purposes they then last forever, and they run a lot cooler too.

harold balls wrote:
My car (99 cutless) has display lamps out. [...] I took it apart and
found four little lamps with a blue piece of plastic over the lamp,
soldered to a circuit board. Only one of the four lamps was working.

Sure, you can solder in some new lamps. I did this to an old car stereo
that had burned out lamps in the display. I was able to get suitable
replacements at Radio Shack, but with their ever-dwindling selection,
this may not be possible anymore.

How does the blue plastic work? Is it a flat sheet of plastic that the
lamp sits next to, or is it a "condom" over the bulb? If the latter,
you'll most likely need to transfer it from the old bulb to the new
bulb. It's easy to find new clear lamps, but difficult to find
replacement lamps with this already installed.

You might try a hobby shop. People like to put tiny lamps in doll
houses and model railroad layouts, so they may have something suitable.

You may be able to use a #18, #73, #37, #74, or #70 automotive lamp.
These are small-diameter wedge base lamps, where the lead wires are
folded against the flat glass base to make contacts. You can
*carefully* unfold the wires to get something you can solder to. The
bulb is probably about twice as long as what you have now, and the
diameter may be a little too much as well, but these are fairly easy to
obtain. The wattage ratings are #18 0.56 W, #73 1.12 W, #37 1.26 W,
#74 1.40 W, and #70 2.10 W. You probably want the smallest wattage you
can get, like a #18 or #73. If you can find a #85 lamp, it's the same
size, but is rated at 1.12 W at 28 V. Running it on 12 V should give
you around 0.25 W, so it may work. Probably the simplest thing to do is
to get a #74 lamp as they are easiest to find, then decide if it will
fit mechanically, then decide if it is too bright. If these lamps fit
mechanically, you might solder a resistor or diode in series with the
lamp to drop the voltage to the bulb a little to dim it.

If you can find a 6 V lamp that fits mechanically, you could buy four
and wire them as two strings of two lamps in series. This will require
a jumper wire that's not currently on the circuit board, but is pretty
easy to do.

You could also install LEDs instead of incandescent bulbs. LEDs only
need around 2 to 4 V, depending on what color they are, so you have to
install a resistor in series to drop the 12 V to something suitable for
the LED. (There are "12 V" LEDs that have the resistor already built
in, but I've only seen these in red and green, not blue yet). LEDs also
have a polarity; if you buy the most common type, the round base will
have a flat spot in it next to one of the leads, and that lead must go
to ground. If the current bulbs have condoms, you could just skip the
condoms with a blue LED. If the blue lens is part of the plastic that
the lamp sits next to, a blue LED might be a close enough blue to work,
or you might install a white LED.

Digi-Key and Mouser both carry Chicago Miniature lamps. If all you need
are a few lamps, Mouser's no-minimum-order terms might be better for
you. Look at page 30 of Mouser's current catalog (at their web site)
for the ones that are closest to what you probably need.

Matt Roberds

I should clarify my reference to "solid state lamps." These are not
simply LEDs, but led-based drop-in replacements for incandescent lamps.
They are designed to run on typical lamp voltages, usually from 6-30V.
You can find them in the DK catalog.

Be warned, though, that they are priced a little different from lamps.

wrote in message
oups.com...
I should clarify my reference to "solid state lamps." These are not
simply LEDs, but led-based drop-in replacements for incandescent lamps.
They are designed to run on typical lamp voltages, usually from 6-30V.
You can find them in the DK catalog.

Be warned, though, that they are priced a little different from lamps.



I haven't looked lately but the ones I've seen were priced at the ridiculous
level, LEDs are not exactly new or expensive devices, and the LED lamps are
little more than a plastic shell with some LEDs and an appropriate dropping
resistor.

On Sun, 16 Oct 2005 01:45:51 GMT, "James Sweet"
wrote:


wrote in message
roups.com...
I should clarify my reference to "solid state lamps." These are not
simply LEDs, but led-based drop-in replacements for incandescent lamps.
They are designed to run on typical lamp voltages, usually from 6-30V.
You can find them in the DK catalog.

Be warned, though, that they are priced a little different from lamps.



I haven't looked lately but the ones I've seen were priced at the ridiculous
level, LEDs are not exactly new or expensive devices, and the LED lamps are
little more than a plastic shell with some LEDs and an appropriate dropping
resistor.

Matt,
Great info! yes the blue plastic is a condom. One of the lamps
were still working and I measured the voltage across it. It was about
10.5 volts. thanks again!

harold balls wrote:
yes the blue plastic is a condom.

Sometimes the base of the condom (where the serial number is) has got a
bit of glue to hold it to the lamp or the circuit board, but usually it's
just a friction fit. You can roll it off of the old lamp and on to the
new one.

One of the lamps were still working and I measured the voltage across it.
It was about 10.5 volts.

It's probably a 12 volt lamp, with the voltage to it dropped down by the
rheostat on the dash that lets you dim the panel lights.

With this new info, I'd try in this order:
1) incandescent replacement at hobby shop
2) incandescent replacement at Mouser
3) blue LED replacement at Mouser or Radio Shack

Like I said, you'll need a resistor in series with each LED if you go
with the blue LEDs. The short cut is to use a 1000 ohm (1K ohm), 1/4
watt resistor in series with each LED. The long cut is to buy a 2K or
5K potentiometer - knob or screwdriver type, it doesn't matter - at
Radio Shack, and temporarily wire it inline with a blue LED. Put the
pot on long wires so you can get to it with the dash put together.
Reassemble the dash, then wait for night and turn on the panel lights.
Adjust the pot so that the LED is about as bright as the rest of the
panel lights, and behaves about the same when you dim the panel lights.
Take the dash apart and measure the resistance of the pot, then buy
fixed resistors of about that same value and install one in series with
each LED.

Good luck!

Matt Roberds

Harold,

I have replaced a few bulbs like you speak of in a GMC truck I used to have.
I am 99% sure I got the bulbs at RatShack. I also replaced some others that
have a little plastic base that snap into a holder on a PC board, you can
get the whole thing, blue condom and all, at a GM parts counter. They were
pricey, but not rediculous. If you lose or tear the plastic cover, you can
also paint the bulbs blue.

As far as using LED's to replace incandescent to replace dash backlights. I
have tried doing this a couple of times, in dashboards and in radios. The
problem with LED's is, they don't have the omnidirectional light output that
a bulb has. They generally put light out at some angle, out the front of the
device. the lighting in a dashboard is usually designed with some kind of
fiber optic plastic 'runner' that carries and distributes light to all of
the panel. So in short, bulbs just work better in this application. If you
replace them, they will probably outlast the rest of the car anyway.

On Sun, 16 Oct 2005 21:34:56 -0400, "Mike W."
wrote:

Harold,

I have replaced a few bulbs like you speak of in a GMC truck I used to have.
I am 99% sure I got the bulbs at RatShack. I also replaced some others that
have a little plastic base that snap into a holder on a PC board, you can
get the whole thing, blue condom and all, at a GM parts counter. They were
pricey, but not rediculous. If you lose or tear the plastic cover, you can
also paint the bulbs blue.

As far as using LED's to replace incandescent to replace dash backlights. I
have tried doing this a couple of times, in dashboards and in radios. The
problem with LED's is, they don't have the omnidirectional light output that
a bulb has. They generally put light out at some angle, out the front of the
device. the lighting in a dashboard is usually designed with some kind of
fiber optic plastic 'runner' that carries and distributes light to all of
the panel. So in short, bulbs just work better in this application. If you
replace them, they will probably outlast the rest of the car anyway.

Thanks for the input, Matt & Mike