just got done figuring out how to fix FD odometer
 

i just got done taking my instrument cluster apart and looking for a fix for the odometer failure. what i found was simple. once you get the cluster pod off and taken apart, you can look at the front side of the gauge behind the actual face and see several capacitors. there were two on my board that had black marks under them where they solder to the board. i then unsoldered the actual speedometer motor that turns the needle on the gauge and pulled the speedo off so all i had left was the board with the odometer screen attached. from there i could remove and replace the capacitors that were bad. they looked like they had burn marks under them but it is actually electrolyte. the type of capacitors used on this board are polarity sensitive electrolytic capacitors. inside they have the electrodes and a paper dielectric soaked in a fluid called the electrolyte. over time these capacitors have a tendency to leak this fluid and cause the capacitor to fail. once they were replaced i installed everything and put it in the car and it works flawlessly now. if there is enough interest in this thread i can post an in depth tutorial with pictures.

matt

There was way too much technical mumbo-jumbo words in there that i don't understand but i'd be interested in seeing the pics anyway, and i'm glad that you fixed the problem!

Interesting. I did a similar thing to fix Bose speaker amps - the Bose units are built with Nichicon electrolytic caps and the panasonic caps are much better lasting. It also solves a lot of problems with stuff like dead cable modems and routers.

Dave

Ok, it's 11:30 pm and I'm bored so I'll do the full tutorial and get it over with.

To start out, remove the cluster and gauge hood from the dash. Then remove the cluster from the back of the hood by removing 4 screws. The next thing that is needed is the proper tools. You will need a soldering iron (lower wattage preferred), some good electronic solder, some desoldering braid, and a phillips head screw driver.

https://www.rx7club.com/attachment.p...1&d=1445641985

https://www.rx7club.com/attachment.p...1&d=1445641985

https://www.rx7club.com/attachment.p...1&d=1445641985


After you have acquired the proper tools start by removing the clear plastic cover from the instrument cluster. This is done by removing two screws (in red) and popping the black clips down on the top and bottom of the cluster.

https://www.rx7club.com/attachment.p...1&d=1445641985

This is the view after removing the cover from the cluster

https://www.rx7club.com/attachment.p...1&d=1445641985

Now you are going to want to remove both the tachometer, the speedometer/odometer unit, and the connection that goes from the back of the cluster to the speedometer unit. The first thing is to remove the three screws that hold on the tachometer (in red). After you remove the tachometer, you will want to remove the one screw holding a cover over the electrical connection that goes to the speedometer (in green). Now turn the cluster over and remove the screw holding the trip reset button to the cluster. After you have disconnected the lead to the speedo and removed the trip reset button, you will want to remove the five screws holding the speedo to the cluster (in yellow).

https://www.rx7club.com/attachment.p...1&d=1445641985

After all of this is removed, now you get the speedo out of the cluster.

https://www.rx7club.com/attachment.p...1&d=1445641985

When you get the speedo out, you are going to remove the unit that includes the face and needle motor. This unit is easily removed (with basic soldering skills) heating the solder joints (in red) and using the desoldering braid to soak up the used solder. The best method to remove solder is to first heat the solder joint, and then place the desoldering braid over the solder joint and then placing the soldering iron tip over the joint, which is under the braid. It will require moving the braid around the connection until there is no solder left on this connection. Now be patient, if this is done correctly, after you remove the two (I think) screws located between these four connections, the motor and face will just fall off.

https://www.rx7club.com/attachment.p...1&d=1445641985

Once the motor and face are removed, here is the birds eye view.

https://www.rx7club.com/attachment.p...1&d=1445641985

Now you can look around real good and see what is loose/burned/leaking. I had two capacitors that had leaked (explained in my previous post) and in the following picture I have already replaced the capacitors. One of the caps I replaced is substantially larger than the original one (I was too anxious to wait for one to be ordered). Below I have pictured what the burn (leak) will look like. I had already soldered on the new one but the black burn mark is still there. The burn will be in red. Just look around, there isn't that much that can go wrong with a printed circuit board, usually its bad components.

https://www.rx7club.com/attachment.p...1&d=1445641985

Once you find the problem components (I hope yours is as easy as mine) remove the bad component and replace it. Removing an electronic part is the same as removing the speedo motor and face. Just hold the braid over the connection and let it suck up the solder. If you don't have a large electronic background, take the parts to your local Radio Shack. The guys (or gals) that work at these places seem to be smart enough to work at an electronics store. If they don't have it in stock, they can probably get it pretty quick. I have not tested the cluster with missing components so I would not drive the car with parts missing.

When you get the parts, installation is pretty straight forward. Clean the board real good with some rubbing alcohol and make sure it is dry. Heat the connections and push the component through the holes. Be careful when applying solder, some of the connections are pretty close together so you might wind up soldering more than one trace together. Use a good high quality silver rosin core solder. Its cheap enough to do right the first time. And don't use one of those huge gun type soldering irons. Those things get too hot and run the risk of damaging the board or other components on it. I use the base model 30 watt pen style soldering iron with the tip shaped pretty fine. This will allow you to get into those tight places without melting everything. When it comes to soldering, more heat isn't always better. Make sure the tip is tinned (thinly coated with solder) and free of pits. Have a sponge or wet towel laying around handy so you can wipe excess solder off the tip. This prevents the nightmarish drip on some random location on the board.

The rest of the job is the reverse of removal and disassembly. Use good judgement, and if you find all the faulty parts, do good solder joints, and make sure to keep your work and area clean and organized, your odometer will spring back to life.

Matt

Nice write-up with pics, very easy to follow for somebody that has no clue what they're doing.

Matt, nice writeup. If you still have the old caps do you mind posting their exact specs so that someone can order the parts in advance?

Excellent! I know a number of people have had dead odometers and ended up getting another odometer with incorrect mileage. This is the RIGHT way to do it.

Thanks a bunch for solving this problem!

Dale

well, i have two used capacitors here. If you look in the picture of the board without the face on it, you will see two replaced capacitors circled in red. the top one is the huge blue one. that is a 1000 micro farad 6.3 volt 105 degree centigrade capacitor. the smaller black one circled in red is a 10 micro farad 50 volt 105 degree centigrade cap. both of these are brown in color with a silver stripe down the side noting the negative lead. the voltage is not as important as long as you don't exceed the voltage listed on the cap. the problem with the voltage rating is that the higher the voltage it can withstand, the larger the cap. i would try to order the exact part because of space issues. also, this might not be the only problem parts, but these are the ones i found to be faulty.

I wish someone could archive this somewhere. Mine is still working and this might help someone save a few hundred bucks. That and it has pretty pictures.

very cool. hope i never have to fix it but if i do i'll refer to this :icon_tup:

Now here's a man who knows his shit !! Good eye Matt.

Thanks for sharing

tom

Again, great stuff!

For those of us that are electronics-retarded, do you have links or part numbers for the 2 caps you used? I can solder, desolder, know how components work, etc. but looking through Digi-Key my mind got stuck in a whirlpool of weirdo terminology for caps. "Uh, I want the ones that look like a two-legged barrel, please".

Thanks for the great work!

Dale

Well a quick search through digikey gives this:
1000uF cap PN#: P10199-ND
10uF cap: P11250-ND

Personally, I'd change each capacitor on the board.

BTW, this thread has been linked in the FAQ.

yes, changing every cap would be a good idea, but i have limited funds so more replacements would require tapping into my food money. i used to own a dsm so i am no stranger to reading and writing tutorials. i'll never miss the car but i learned a lot about working on things and being frugal while fixing something.

ok, so i replaced the capacitor that was blown out with the exact 1000microfarad cap that you used and no go! what is a way i can test each cap to see if they are doing their job?

there is no real way to test a capacitor without expensive testers. another thing to be careful about is making sure you don't overheat the capacitor. if you are trying to get the cap to go through the board and it isn't cooperating hold off and let it cool. i know most electronic parts are very heat sensitive so if it gets hot you fry it. make sure you find all the bad components or it still might not work. i overheated one of the parts i replaced and the odometer worked for about five minutes and then it died again. also, make sure you install the capacitor in the correct direction. electrolytic capacitors are polarity sensitive. if you are replacing the top capacitor and using the huge blue one i have in my picture, the polarity stripe should go down. if you look carefully at the little diagram on the board where the capacitor goes you will notice a little negative symbol beside one of the holes (the lower hole). if you install it backwards it is instant ownage. i wish there was a way to edit my tutorial post because i forgot to mention the importance of polarity. if i could get a moderator to edit the post or something to mention the installation direction, that would be great.

So does anyone have any idea what the different capacitors are for? I had a friend who repairs circuit boards rather frequently replace the two capacitors that turbo blue did and it unfortunatly didn't fix my odometer problem :(. If noone else has any good info i'll probably just have him replace them all as capacitors aren't TERRIBLY expensive. Would be nice to rule some of them out though.

Just replaced the 1000 microfarad capacitor with the same capacitor that Turbo Blue used from Radio Shack with positve results. Odometer is still displaying as advertised. Pulling the instrument cluster was a challenge but with a tug here and there it finally came out. After removing the cluster I just followed the instruction that Turbo Blue posted with the exception of removing the speedometer from the circuit board. The capacitor was accessible for replacement. Turbo Blue.....if you're ever in San Antonio let me now. I owe you a beer!

ok so what was wrong with it??? the speedometer was bouncing or something? because mine does that randomly sometimes... rarly now

My odometer digit display went out. The only thing you could see was the background lighting.

please send information.
 

Please send the detailed info to the rx7 email list, or tell us where to find it.
Marc, 94 rx7

I just want to say thanks for thread and the big blue capacitor is the one to replace if your numbers go out.

my trip odometer records miles but it doesn't zero. what's the fix if you know?

thanks,

howard coleman

LOL, I have ZERO tech skills.

That said, have you messed with anything in that area? I could see the plastic reset "rod" coming loose (mine fell off while taking the cluster apart) and if loose it just snaps back into place. The resetting unit itself seems to just be a simple on/off type of switch, maybe it went bad?? Also IDK if this has anything to do with it but there is a small plug that plugs into the area of the trip counter reset but I didn't look to see if it was related to the trip counter itself. I dont see how that could come loose without someone unplugging it.

Im sure some more knowledgable people will have a better answer for you.

.

It's also a nice view of your matching socks :)
:rlaugh: :icon_tup:

i just knew some one was going to mention that :D
Thanks for the write-up :) i will be needing it soon

How hard would it be to remove the digital odometer, and swap it out?. I replaced the entire cluster/hood(car had hack job indiglo). the odometer now shows 20k less. I don't think this will float during inspection.

Does any one have the electrical diagram of the instrument cluster ? The problem for the cluster i am repairing seems to be a tab bit more than just the capacitors.

Thanks :)

my tach will some times just jump out to crazy rpms. im going to take a look when i get the chance. nice write-up!

cool

You Just Saved Me $300!!! Thanks Alot

I made a list of the caps, quantity and Digikey part number for all of the caps on that board (from my 93). I was about to order these, but I figured out that the ground was the problem (X-14 connector in passenger footwell). I noticed that messing with the ground made the tach jump around too, so those of you who have jumpy tachs the ground might be your problem and not the caps.

1000 micro farad 6.3 volt 105 degree C 1 P10199-ND
10 micro farad 50 volt 105 degree C 2 P11250-ND
47 micro f*** 25V* 105 degree C 1 P10267-ND
1uf (micro f) * 50v* 105 degree C 3 P10312-ND


- Chris

Do you know quantities needed of each?

My tach is fine, but the speedo reads anywhere from 0-15 MPH fast.

mine too my mpg mostly

You checked all around this area?

https://www.rx7club.com/attachment.p...1&d=1182268419

Yea , sorry the quantities are in there, they just formatted weird after copying from excel. They are listed right after the "C" and before the part number.

Heres a clearer version

1x 1000 micro farad 6.3 volt 105 degree C 1 P10199-ND
2x 10 micro farad 50 volt 105 degree C 2 P11250-ND
1x 47 micro f*** 25V* 105 degree C 1 P10267-ND
3x 1uf (micro f) * 50v* 105 degree C 3 P10312-ND

Thanks for reformatting! I just couldn't make out that those were quantities.

hi i have a prob with my meter too. i changed the required stuff and it did work for one day then it decided to stop working again. did i do something wrong? i am using 300km meter. thanks guys

does mazda even sell those parts over the counter? anyway, they are different from the radio shack parts, here is what I picked up, does it look alright?

these should all be electorlytic radial (PCM) capacitors right?

not the axial in-line capacitors? radio shack had both, but since I havent taken my dash apart yet, i figured they are all the PCM type.

15 and 30 watt switchable new solder iron. $10.99
desoldering braid $3.99
Silver solder #3.99

1000uF electrolytic capacitor 35WVDC 85 C #272-1032 $1.59
47uf electrolytic capacitor 35WVDC 85 C #272-1027 $1.19
10uf electrolytic capacitor 35WVDC 85 C #272-1025 $.99 (2 needed)
1uf tantalum capacitor 35WVDC 85 C #272-1025 $1.59 (3 needed)

total price $30.85 (tax dependant)

doesn't matter if its tantalum, right? but the wattage looks smaller then recommended. do these parts look ok?

the original 1000 cap said 6.3v? I didnt find this in the store, should I special order it?

Hey guys, i have a question about this, after changing the gauge faces to a custom design and removing the needles and such my speedo is no longer working correctly, the issue its having is the speedo is taking a long time to go to the proper speed so when i accelerate to 0-60mph and cruise, the speedo slowly climbs up to that speed about but not accurately @ 60 but 5-7miles off, and when i stop 60-0 or what ever, once the car is stopped, i see the needle slowly coming back down to 0....

Any ideas would be appreciated on how to fix this or what you think needs replacement!!!

Thanks...

I posted Digikey part numbers. The entire order is probably $5 total from them, plus you can get exactly what you want.

I have no idea on the tantalum.

Assuming the speedometer needle is on a wound coil-spring, it sounds like you lost the "pre-load" on the speedometer needle.

If you didn't mark it before disassembly, it will be a trial process to find the proper mounting of the needle.

Good luck.

:-) neil

you can use any equal or higher voltage rating as long as it fits, since the physical size increases with the voltage rating. but i would use the same construction, ie electrolytic or ceramic and not switch to tantalum

Also if you want them to outlast the original caps go for the higher temp rated ones like 105C instead of 85C since electrolytics are very sensitive to temperature.

I ordered these caps from DigiKey 2 weeks ago.

Total cost, including shipping, was about $10.

I successfully transplanted odometers tonight following Matt's directions. Big thanks for the help!!!

need small help i've bought plazma clocks for my rex, im haveing proble powering them were is the power on the clocks

Hi guys, I had replaced these two capicitors earlier, to no avail. When i took it back apart i realized that there were some black marks under some of the other components (circled in blue) are these replaceable? and what exactly are they? Diodes? transistors? I'm not very informed on electrical parts and what not. I figured i would give it a shot, so i would have a working odomter again.

Thanks

Harrison

ok, so the parts i circled are diodes. problem is that by just looking at them i have no idea how big they are. two of them say "A" and the other one says "C". anyone know the size and voltage i need?

They loook fine to me, test them using multimeter.