How Does This Work? (And How Do I Fix It?)

It looks more like a fluorescent type digital display (I may be wrong). If so, you're display driver IC may be toasted and needs replacement.

If it's an LED display, your display driver IC may be toasted and needs replacement.

If it's an LCD display, your display driver IC may be toasted and needs replacement.

Other than that, I can't think of any other parts that may be bad...except for the display itself.

Definitely a vacuum fluorescent tube display...

Not much you can do about them except replace it with a new part.

John.

It is a VFD (Vacuum Fluorescent Display), so adding a backlight will not help. You said it was intermittently broke, so I would suspect a bad connection somewhere. Inspect all the solder connections, use a lighted magnifier if possible. Look for a tell-tale "ring" around the lead, in the solder fillet. This ring indicates a possible broken solder connection. If you spot any of these, remove the existing solder, and re-solder. If you don't see anything that looks suspicious, you could try to just touch-up all the solder connections. The heavier the component, the more likely it is to have a broken connection. Vibration and temperature extremes are hard on electronics.

If you can power it up outside the car, it would make troubleshooting easier. You can flex and press on the assembly and see if you can isolate the most likely area of the fault. Good luck! Let us know if you get it fixed.

Tom

Yeah, I found out today from a guy at work who's more into electronics than I that it was a VFD. The problem was intermittent at first, and now the display will not light at all. I went to the Chevy dealer this afternoon, who couldn't do anything for me. When they get a cluster in that has this problem, they send it out to a third party company for repair. I contacted the company that does the repairs (who are barely a couple hour drive away from me) and they refuse to do anything for me unless I send the entire cluster in, not just the board pictured above. They also won't just sell me the part, the board, or even tell me where I can get the components.

My parents drove this car for 5 years without being able to read the odometer. I just bought it off of them, and it's driving me nuts! Sadly, I think I may have to continue driving it like this :(

Did you try to look it over real well? You might just suprise yourself and fix it .

Tom

of course! Any excuse for an easy way out. :-P Alas, it's b0rked beyond simple benchtop solutions.

Only one way out for you Mr. Wizard, I really don't like saying it like this, BUT, HOWEVER: as everything manufactured today is created with a limited life span, few repair parts are available, and even fewer repairmen bother to learn how to make these repairs.

Live with your problem, until you can find after market parts or journey to your local salvage yard and pay 1/2 the estimated new value for one that is promised to work, "they think" or maybe they can find you another one someday, on the internet.

Next option. Sell the car and get another one.

TMF

Quickest and most enjoyable way is to visit a U-pull-it type junk yard. Bring a list of any other parts you might like to replace also (sun visors, lamp lenses, window/lock switches, add a clock option...). One time, while looking for a dash facia so I could add a passengers side side view mirror (the control was mounted in the dash), I ran across a Chevy police car. I came away with a set of silicone radiator hoses and both sway bars (after checking to verify that the police car units were bigger). It made my car, '85 Olds, A LOT more fun to drive.

You also get to observe some of the newest engineering designs in body and engine manufacturing. (Saturn wasn't the only manufacture using glue-on plastic panels) Bring a lunch.

(Saturn wasn't the only manufacture using glue-on plastic panels) Bring a lunch.

Most panels are now glue-on plastic or metal makes no difference.

I had the same problem with digital clock.

Nothing is wrong with your display. There is a little lamp that illuminates
the display and this lamp is burnt. Simply replace this lamp.

Carefully unplugging each part and plugging it back in can cure some bad connections, but unplug and replug one part at a time just to be safe.

In a car environment, pins often get high resistance contacts, that will clean the contacts and maybe you will get lucky.

That goes for the cable attachments too.

I have successfully repaired a great many of these types of units. about 90% of them suffer from bad solder joints. (heating and cooling, expanding and contracting + bumpy roads cause intermittent cracks in solder joints. Except for a very few, it was quite obvious with a little observation where the problem was. Usually, one bad joint is the current problem, but you need to repair any questionable joints also as they will soon fail. Remove old solder, clean connection well and re-solder with new solder. (DO NOT MIX LEAD-FREE AND LEAD SOLDER). I doubt that the problem is on the board you show on your post. Fluorescent displays usually require from 50 - 75 Volts to Illuminate. This voltage is generated from your 12 Volt battery supply using a DC - DC converter. It is most likely located on the main board that the display was attached to. (This is the main reason that repair shops will not accept the board for repair without the rest of the unit.) Good luck & let us know how it turns out.

If all else fails, IE you can't fix it and it drives you off the end. Epoxy a magnet to the drive shaft or axle set up a sensor and do the math. Use a readout on the dash some wheres and make do.

No reason to replace a decent useable car because of a damaged accessory.

Agreed with the last part - I would NEVER give up this car for something so simple. It's a '96 Impala SS, an amazing car in itself with (hypothetically, lol) very low miles. It was my parents car like I probably said earlier, and aside from a couple trips between FL and NJ, the car averaged only about 6-8000 miles per year.

I'm trying to keep it as original as possible, so I'd prefer not to go mucking around with custom sensors, wiring and readouts. Thanks for all the help, guys!

General motors, like all Mfg.'s uses these kinds of parts in multiple different models and often for several years. Why not contact GM and ask them for their advice regarding the problem. Likely you are not the first person to encounter this one. Be nice to them and tell them "Joe sent ya!

TMF

I've already done this. They have, indeed, encountered this problem often. They have to ship the entire instrument cluster (not just the bad component, thus leaving me without gauges for 3 weeks or more) out to a place that repairs this type of equipment. Lucky for me, this place is about a 2 hours drive away, which would be nice except that they refuse to sell me any components, they will only do the work themselves, and I think they even told me I have to go through the chevy dealer to get the work done.

Sad, really.

2 hours drive, so far from your place.

if its vfd, check cathod filament, to see if there is -44v voltage existing.

weld off these pins show us the below chip, so that we can check the device and then you can buy new one.

its easy to buy in an elelctronic shop.

You mean " unsolder this chip" I feel.......in English different terminolgy is used depending on the type of connection, using lead based or leadless metal to connect different metals we call soldering, relatively low temperature, so as not to damage the components.

Even higher temperatures can still be called soldering with say a silver compound.

Soldering with brass as the filler material is called Brazing for some (unknown to me) reason....

Welding is done (mostly) by melting two metal pieces of the same type of metal to be joined together, and filling the resulting hole with by melting a further piece of the same metal......

Soldering connecting maybe unlike metals with another metal.

Welding connecting like metals with the same metal. (Though some welding practices stretch this definition a bit, especially today.)

If there is someone out there that can define this a bit better I would be most grateful indeed.

unsolder!

you are right. I vote to add score for your thread.

I forget the word solder at present. sorry.

weld usually use for arc weld etc. strong power. while solder may use for electric iron. small power, is it right?

thanks for mention.

if you use a large weld machie or gas welding torch. the device will become gas.

seperate the display chip from the below chip carefully. so that we can see the brand of the chip

No problem, your English is usually quite good, and we all knew exactly what you meant even before my explanation!

It was just to help you little with the correct English word!

There is still something wrong tech description in my above #18 thread. Im still waiting for your pointing out.

hope all of you can find out and correct.

Release the weld and depress the melt key

replace the display, as we know the display systems has some life period, when it crosses that, then properties of it changes.

Why not try looking for an electronics whiz kid somewhere and ask him if he can convert it to an LED type. I know that it defeats your purpose of preserving everything as it was but if nothing else works, you can go this way.

I remember once seeing an application note for a display driver that can be adapted to use vacuum flourescent displays or LED displays. I don't know what chip you're using, but it might be worth a shot.

ignore a lot of the rubbish in this thread so far, that is a VFD .. it has no lamp, no backlight. 2 things are likely to fail, they are a valve, they need a heater for the electrons and an accelerating voltage.

they do fade over time as emission drops, but total failure is likely one of the above 2 things.

the 2 end pins are usually the heater .. one wya is too look at the display with a CCD camera, the heaters are wires across the front panel and can usually be seen with anIR sensitive camera. Often a fusible resistor can fail in the heater circuit. the heaters are in parallel and rarely break. If one part breaks the the display will be brighter on the top or the bottom. Can often drop the heater series resistor to increase the brightness, the wires can glow dull red for years without dieing.

I reckon the prime suspect would be the inverter for the high voltage supply. It should probably be around 90v or more, look for any high voltage electrolytic caps on the pcb and measure across them .. a 160V cap with 0v on it will give you a hint. There will be a transformer or inductor as well there somewhere.

I can't see from the pics where the HV supply is .. i assume its on the back of the PCB.

Set to 42,000 Joule... Charging.... CLEAR! *bzaat*

Dead thread revived.

Sorry to ditch the discussion for a while, but I left town for a week, then was busy with work and registering for classes when I got back... I finally removed the VFD from the board, and was able to get a part number from it. It's a Futaba 16193139, and there is an AMI IC beneath it. I have an email sent out to each manufacturer looking for datasheets, and Futaba is hopefully going to reply with a local distributor where I can buy one or two of these blasted things...