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Soldering Required to Replace Instrument Panel Bulb

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Not a good decision
tekochip   4/15/2014 8:36:55 AM
I worked on a project where the decision was made to solder a bulb in place.  The sentiment was that the bulb was a super high reliability bulb rated for high vibration and an outrageous number of hours.  I was against it because if the bulb failed you knew full well that somebody was going to run down to Radio Shack and buy the first bulb that fit into the board, and it wouldn't be the best bulb.  Most units made it through the normal life span, however the unit was used outdoors and some units failed when the leads corroded off the bulbs.
Good incandescent bulbs are getting harder to find and the prices are going up.  Coin operated games used to use mountains of them, but now the game manufacturers are looking for alternatives.

William K.
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Why are the bulbs soldered in?
William K.   4/15/2014 10:14:25 AM
Soldered in and hard to replace incandescent bulbs are a pain, no doubt. But the improvement in assembly reliability by avoiding a socket is real, and the price of a baseless wire-lead bulb is a bit less, so they get soldered in. And most of them last a long time.

One large item that stands in the way of using LED illumination is color variability in white LEDs. Most incandescent lights are all the same color and dim in a similar manner, while white LED devices have quite a spread. That is one driver behind the intensly colored displays that do use LEDs. Stylists and other picky people demand that all of the light sources on an instrument cluster match colors, and that increases the costs of the LEDs quite a bit. Advances in production are reducing the cost, and brighter devices reduce the number that are needed, but it is a more recent change. That is why there are soldered in bulbs.

Nancy Golden
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Not Just Soldering - Getting To It
Nancy Golden   4/16/2014 6:35:08 PM
And even more surprisingly is the extent you have to go through just to get to the bulbs:

"Not only that, but you have to remove all the needles from the gauges to disassemble the instrument panel enough to get to the bulbs."

What a nightmare for replacing a part that is known to have a finite life and may fail.

Cabe Atwell
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Re: Not Just Soldering - Getting To It
Cabe Atwell   4/24/2014 2:38:47 PM
No doubt the manufacturer designed the speedometer to rip people off when a simple bulb replacement is all that's needed. You should just 'roll' the miles back on the speedometer and sell the vehicle back to them at a much higher cost.

TJ McDermott
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Re: Not a good decision
TJ McDermott   5/8/2014 2:20:07 AM
What does it mean when half the bulbs in the instrument cluster fail over a period of 12 months in a car 8 years old?

Is it that bulb life was reached and they're actually pretty consistent in their length of service?

Or does it mean there's something wrong in the electrical system that puts surges into the lamps?

User Rank
Maybe yes maybe no...
HarryB   5/8/2014 3:24:16 PM
As has been pointed out, the soldered connection could be more reliable than a socketed bulb (vibration, corrosion etc.) It may be that the bulb costs .$25 cents and a  socket raises the price to $2.50.  I too am sad that products are not built to last but we have our own capitalistic greed to blame for that... who would build you a 25 year life span product when they can sell you a new one in five... It's also getting to the point where another engineer is the only one clever enough to fix a failed product.

User Rank
Re: Not a good decision
Ockham   5/8/2014 3:32:08 PM
One thing that it may mean (when bulbs start blowing) is that the voltage regulator in your automobile's alternator has gone bad.

Incandescent filaments which are subjected to over-voltages can and do fail with distressing frequency. When an electronic or mechanical regulator fails and your alternator zaps your electrical system with 16 or 18 volts, it is not unusual to see the filaments fail...even when other electrical things don't. Filaments are defenseless against overvoltages.

Check your alternator and grounds.


bob from maine
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Re: Not a good decision
bob from maine   5/8/2014 3:56:58 PM
TJ: I've had customers with this complaint - incandescent bulbs are sensitive to over-voltage and cars that burned-out headlights, dome lights, brake light bulbs frequently would trace back to a faulty voltage regulator or a loose ground allowing the alternator voltage to rise to above 15V. Now most alternators have built-in regulators but in the bad-old-days the regulator was mounted on a fender somewhere and often the wires would get pulled out or corrode. I had a Volvo 144 that would burn-out the left front headlight every 6 months. The reason turned out to be the hood was vibrating at speed and this vibration was transferred down to the headlight bulb and breaking the fillament. It turns out it was a common Volvo 140 series problem and was cured by adjusting the hood stand-offs. Some service techs knew this, but because of the way the dealer shop worked, the word never got to the other techs until the service writer did a "hurry-up" replacement himself and the tech told him about it.

User Rank
Same thing on old stereo gear
tomintx   5/8/2014 4:21:14 PM
I have this weakness for 70's era mid-high end stereo gear (no tubes, I'm not insane).  I have an FM tuner which has these nice little Left/right bulbs which help the user to tune right to the center of the frequency.  Of course they long ago burned out.  I managed to replace them with LED bulbs in the right colors, and it actually works pretty well.



User Rank
dont get mad, get even
oldjimh   5/8/2014 4:49:21 PM
That the issue has created a 'cottage industy' as an earlier poster noted tells me it's not an uncommon failure for this line of vehicles. Surely it was a manufacturing decision to save a step,  perhaps manual insertion of the lamp.   Chances are the panel itself is subcontracted.

When i get really mad  i go to the manufacturer's website and click on "investor relations".  Then i find the CEO and write him a personal, handwritten note explaining he has a problem with either his design or procurement department  which if unchecked will destroy his repeat customer business.

A sample  panel from a junkyard would really make the point.

But to an immediate preventive action  - incandescent lamp life is inversely  proportion to about 12th power of applied voltage.   Running your instrument lamps just a little below  full brightness will extend their life for years. 

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