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Author Topic:   Garmin GPS 492 Backlight
swist posted 05-18-2013 08:32 AM ET (US)   Profile for swist   Send Email to swist  
It looks like the LCD backlight on my Garmin GPSmap 492 has died. The model is not current and I cannot find any information on the web, nor in the manual, on how to replace the backlight, or if it is even possible. It may be integrated with the LCD screen, and I am certainly prepared to get a new screen, but that doesn't seem possible either. It looks easily replaceable.

Even the outrageous ($250) fixed price repair service from Garmin shows "Repair no longer available".

There are completely new units available from various sources but I am surprised how expensive they are considering the unit is obsolete. Saw several around $450 (list price was something like $550 6 years ago. Lot to pay for a new backlight.

Does anyone have any other information on the least expensive way out of this?

jimh posted 05-18-2013 08:47 AM ET (US)     Profile for jimh  Send Email to jimh     
I can see three scenarios for repair:

--buy at low cost a similar used unit which has become non-functional for a different reason, disassemble that unit, remove the back light assembly, and install it in your unit; retain the other unit as a source of more spare parts

--find a source for a new back light assembly as a repair part, buy one, install it yourself; you may find that the back light assembly is a common part and can be sourced from eBay or Amazon;

--contact the manufacturer, express your deep disappointment at the service life of their product, and receive a generous trade-in credit for your old, non-working device in exchange for a new device of a newer model.

swist posted 05-18-2013 09:14 AM ET (US)     Profile for swist  Send Email to swist     
Thanks, the last scenario I had not considered, and anecdotal evidence on this board would indicate Garmin has good customer service. All I need is the screen, it would not even cost them a new unit. The screens are common to a number of different models of that generation. Surely they can put their hands on one.
jimh posted 05-18-2013 10:31 AM ET (US)     Profile for jimh  Send Email to jimh     
ASIDE: Regarding replacement or repair of LCD computer displays or back lights. I used to manage about 30 corporate laptop computers that were used on the road in very heavy duty service. They had a three-year warranty and we really got our money's worth out of the warranty. The factory field service technician was visiting us about once a week to make some field repair under warranty. As a result I had the chance to watch him tear down and replace just about every part of those laptops. Being quite comfortable working with this sort of equipment, I began to just ask the laptop manufacturer to send me the repair parts. I could install them myself in a few minutes, and it saved having to wait for the field technician to call, make an appointment, and come out to do the replacement. Typically the repair part would be there in the morning from overnight delivery, and I could get the laptop back in service in less than an hour. This was better than waiting around all day for the technician to arrive--it seemed like he always liked to make us the last stop of the day.

I got to be very familiar with the particular model of laptop we were using, and I could tear one down, install just about any part, and reassemble it--with the usual assortment of about 25 very small screws of all different sizes and types.

One laptop lost the display backlight. I figured, heck, I am good at this, I will install it myself. On the telephone with the factory tech support, he suggested I let the technician install it. I asked him to just send it, I would install it, I was skilled at this sort of thing. He cautioned me that it was a fragile part to install. No, I said, let me do it.

The display and back light assembly arrived the next day. I installed it. Guess what? It did not work. I had to call tech support and have them send another, this time with the technician to come to install it. Apparently there was a real technique necessary to install these without blowing them up in the process.

I offer this anecdote as a caution about trying to make the repair yourself. Even with about 40 years of experience working on all kinds of electronics, I managed to blow up the back light when I was installing it. I think the older liquid-crystal display backlights use a cold florescent cathode lamp. There is a voltage step-up convertor in them that boosts the supply voltage up to a higher level to light the fluorescent lamp, and apparently that device is a bit touchy.

swist posted 05-18-2013 11:03 AM ET (US)     Profile for swist  Send Email to swist     
I too have done a fair about of component-level replacement in computers, but never an LCD screen assembly, so I will have to be careful, if I can even get one (I sent an email off to Garmin politely suggesting that if I can get parts for 30-year old Sears appliances, they should be able to support something 6 years old). Surely they must have dead units with good screens hanging around.

It looks like the display/backlight are self-contained. It is actually a part of the front panel, which comes completely off with about 8 screws. It connects to the rest of device with a detachable cable. And the screen is the only active component in this subassembly, all the buttons, card holder, etc are actually in the base unit and protrude though cutouts in the front panel. It may be that the display is a permanent part of that panel and cannot be replaced by itself, but you would think that wouldn't make the cost too much more as the rest is gray plastic with holes in it. If this is true, it's a matter of removing the front panel, detaching the cable, attaching the cable from the replacement panel, and putting it back on with 8 screws.

So it's pretty simple on the surface, but I fully believe it when you say there may be dragons lurking underneath the surface.

jimh posted 05-18-2013 07:08 PM ET (US)     Profile for jimh  Send Email to jimh     
The assembly sounds good. Maybe you can find a dead unit whose display still works and just swap them out.
Ridge Runner posted 05-19-2013 10:06 PM ET (US)     Profile for Ridge Runner  Send Email to Ridge Runner     
If taking the front panel off allows the gaskets of the body to loosen up the you will need to flow dry nitrogen into the case during re-assembly if you don't condensation may occur in the future.

swist posted 05-20-2013 10:49 AM ET (US)     Profile for swist  Send Email to swist     
It did not take long for Garmin to get back to me saying they can't help because they really don't have the parts. I find this dubious, but it doesn't matter since they are obviously of no help.

My observation is that the price point at which consumer electronics are declared obsolete after a relatively short life, and shortly thereafter are declared unrepairable, keeps going up and up. Cell phones have been unrepairable for some time (if they do "repair" them, it's by throwing it out and giving you a new one).

I predict it will not be long before $3000 70" TVs are in the same category. They make so much money on extended warrantees they can easily give out new units instead of repairing them.\

I'm probably reflecting my age, my this seems like craziness.

But back on topic, I actually did locate the part on eBay in Hong Kong - the English in the item description is pretty funny, but on the other hand, I don't speak Cantonese, and their eBay seller rating is excellent.

So it's on to home repair - I am concerned about the comment by Ridge Runner - is there any simple way that the unit can be reassembled to minimize the water vapor trapped?

Ridge Runner posted 05-20-2013 03:42 PM ET (US)     Profile for Ridge Runner  Send Email to Ridge Runner     
swist - I saw that on ebay... pretty expensive... I also saw some Garmin units that seem to be cheaper... the display on the 492 is the same as the 498 and goes all the way back to the 292/298.

I have not done this but I was told that you could likely just keep one edge of the case slightly open and use a gentle flow from a nozzle on the nitrogen bottle to displace the air inside the case as you close it and tighten the screws.

swist posted 05-20-2013 04:15 PM ET (US)     Profile for swist  Send Email to swist     
The ones on eBay were new. Yeah, kind of expensive, but if I buy a used 49x/39x/29x, I really won't know how much life is left in the backlight.

I have the impression that this is a frequent point of failure in these units.

I'll look into someway of dealing with the trapping of moisture on reassembly - maybe some kind of dessicant - not sure where I would get a stream of nitrogen.

Considering how many GPS units there are in the world now, I'm a little surprised that current Marine units are still so expensive. I say a "little" surprised because I'm sure it's probably the usual Marine low sales volume factor.

jimh posted 05-20-2013 11:45 PM ET (US)     Profile for jimh  Send Email to jimh     
This must be bad karma--the backlight on my laptop died today!
swist posted 05-21-2013 09:19 AM ET (US)     Profile for swist  Send Email to swist     
Jimh: Do you intend to try to fix it? Many computers are now underneath the "not worth it to fix" threshold. From a little investigation into the technology, it appears that LCD backlights are seriously integrated into the rest of the screen, so at a minimum, you must replace the screen (as I have to on my GPS). They appear to be some sort of very specialized fluorescent light, which typically have a long service light, but they are still light bulbs...presumably they have filaments which are fragile.

I note that within the last couple of years, fluorescent backlights are becoming obsolete on TV screens, being replaced with LEDs that light from the edges. Don't know it this will (or already has) come to marine electronics or computers with small screens. One would think this would provide a longevity benefit (and supposedly a better picture, but I doubt you would notice that on a laptop or GPS screen).

swist posted 05-28-2013 03:49 PM ET (US)     Profile for swist  Send Email to swist     
Just to close this out, I was able to successfully install the new LCD assembly. Little trickier than I thought mainly because PC board, back case and front case are all connected to each other with very short cables and it would have been very easy to rip things out. LCD assembly connects to main board with a ribbon cable of the type that doesn't really have a connector - it slides into place and then is held there by a plastic clamp - I've never seen wires so close together on a "connector" but it did work.

I did not do anything to protect against trapping moisture inside the case other than working in a very dry room on a very low humidity day. We shall see.

Ridge Runner posted 05-28-2013 05:16 PM ET (US)     Profile for Ridge Runner  Send Email to Ridge Runner     
Did you purchase the display panel on eBay? Did you get the one from Hong Kong? Just wondering….
swist posted 05-29-2013 09:34 AM ET (US)     Profile for swist  Send Email to swist     
Yes, the eBay/Hong Kong deal was the only place I could find a new replacement screen. Expensive, but as you all have noticed, the price of marine electronics is not dropping like in the consumer world. Not enough market. I'm just not prepared to buy a new one.

I'm still annoyed Garmin was so little help on this.

jimh posted 05-29-2013 12:18 PM ET (US)     Profile for jimh  Send Email to jimh     
Congratulations on making a successful home-brew repair to your GARMIN marine device. I think this puts you in a select club--guys who can fix major problems in their expensive marine electronic devices.
swist posted 05-29-2013 03:16 PM ET (US)     Profile for swist  Send Email to swist     
Hold off on that for a bit. I didn't reassemble it in a room full of pure nitrogen.
jimh posted 05-29-2013 04:01 PM ET (US)     Profile for jimh  Send Email to jimh     
Don't forget that regular air is already 80-percent pure Nitrogen.

The interest in having Nitrogen is due to its tendency to be very non-reactive, while Oxygen is by nature highly reactive. Maybe you can make a small rubber filler hole like those used on an air-filled sports ball like a basketball, and insert an air needle to instill Nitrogen. You can usually find Nitrogen at the local tire retailers, where they love to sell it as an add-on to every tire sale. Maybe a $1 whiff of Nitrogen will pressurize your GARMIN to long-term good electronic health.

swist posted 05-30-2013 08:17 AM ET (US)     Profile for swist  Send Email to swist     
Hah. I did learn from this experience that the gasketing and sealing system is "just OK", mainly designed to keep rain and sea spray out. And the unit doesn't have a rubber filler hole (it should). No way is any special gas mixture going to stay inside for long. My guess is its final assembly is in a dry room with some sort of simple drying process to make sure all the inside components are dry before being sealed up.

$600 may be a lot to us, but it doesn't justify assembling the unit with any complex regard for what's trapped inside. The insides are the same quality as any other cheap consumer electronic device I've disassembled. As the backlight experience would tend to indicate, something will break long before any trapped oxygen and/or water corrodes something.

As I said in some other thread, at my age I'm still having trouble accepting that electronics work for a while and then you throw them out when they break. By that time they're obsolete anyway, so you're expected to buy a new one. I hope we're not building airplanes and skyscrapers with this philosophy.

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