For those who aren't willing to risk damaging their boards, or don't have time to troubleshoot this, there is a guy on instagram @michael_gagne if im not mistaken, who does a VERY good job repairing the entire meter from all sorts of issues (needles, screens, odometer, tripmeter, caps, etc..). He does it for a relatively low price and is in canada, and would get more than likely the day he receives it. Check it out and dm him, his instagram has lots of pics and videos of his work. This is great for those of us with the rare and ridiculously expense meters. I don't know if he has an account here otherwise i'd mention it. But this is for what its worth. Cheers!

 

@Mugen1800,

Thanks for sharing that info. Are you speaking from personal experience with regard to using Mr. Gagne's instrument cluster repair service? What was wrong with your cluster?

@johnd08,

Did you share any photos of the front side of your speedometer? As mentioned before, you do not need to remove the speedo face. I want to gauge the condition of the components and/or verify the polarity on capacitors are correct. Please use a flashlight to help with components under the speedo face.

With the cluster out of the dash, you will need to verify the wiring going to the cluster. We are only going to focus on signals that will go to/from the speedo board. Did you locate the other manuals - BEM & WDM? I also will refer you to another thread - look for "FD instrument cluster flex print". I made a schematic of the flex print on the instrument cluster and it WILL come in handy during your wire troubleshooting. Download the file and print a couple of copies, have a clean one for reference and others to take notes or mark up.

The current objective is to verify the car's wires are good. If they are good then the problem may still be within the speedo. Unless I am mistaken, the repair shop claimed your speedo worked after repairs and they suggested the problem is in the car's wiring. If I haven't said this yet, then we need to take a logical approach to finding what's wrong with your speedo. If there is a wiring problem then we need to address it.

When are you planning to check the wires?

 

George,

I will take photos of the Speedo this weekend and post. I have to pull the car in and out of a trailer into a garage in order to actually work on the car which is a bit of a chore. One step at a time. I will also see if I can download manuals this weekend.

Mugen 1800

Thanks for your input. I used Atlanta Speedometer for a rebuild of the cluster and they claim everything checked out on the bench before they returned it to me. Now trying to chase down wiring under the guidance of someone who knows what they are doing.

 

@Gen2n3
I used 2 clusters, my first was the OEM one with 180km speedo, but after having my engine built and ported i switched to the 300km mazdaspeed one. Only problem is the needles for speed, rpm, and temp sometimes stick on startup. Its fine once the vehicle is operating (and after a love tap to get it to jump to its proper location). I bumped into michael_gagne work on instagram and saw others with similar and way worse problems. I will send this one to him once the temperature warms up since cold and pulling that meter hood doesn't mix (this is my second hood....). I fixed my first meter which had the common odo blanked problem. But he does a way better job IMO. He has a happy audience on instagram so i figured i'd share for those who can't do any of this, or just don't want to. OEM is cheap to replace for me if i had messed up or something....but i won't touch my mazda speed one. All i did on that is adjust resister for wheel size to reflect my speed better.

@johnd08
Oh wow they're a bit pricey. Did they send you pictures and video of repair and operation? Im sorry to hear you're still having trouble with it afterwards, thats the worst mate. ...

 

Mugen,

Thanks for sharing the background on your speedometers. Are you still in Japan or in another part of the world? I figure that you would use someone local (if not in the US) to make the electronic repairs. I wish you the best of luck in your repair work!

JD,

I look forward to your post on the speedo photos.

 

@Gen2n3
I am still in Japan yes. I'll have another year here before leaving to the UK. The RX7 comes with of course . Its pricey and hard to get people to work on your car here. They're terrified of the rotary in some places, or aren't careful so i just do it myself unless it requires a special tool or facility. The mazdaspeed meter is too expensive for me to go having fun so thats why i'd rather have the lad i mentioned work on it. What you're telling John is pretty sound from personal experience, did he already check that the inputs to the meter were in spec? In case it was working some overage cause damage to it again. He was checkig his grounds but i didn't see if everything was ok'd or not.

 

So, here we go trying to upload the photos from today.










I see the residue around the solder points in this photo.

So, after the last response from Mugen I thought I would re-contact Atlanta Speedometer and ask them specifically what components they might have checked or replaced.

 

It looks like they at least switched out some capacitors on the speedo board. The red ones. I could be wrong though. I've just never seen factory ones in that colour. But I agree with Gen2n3 on not taking apart and soldering anything if the alanta people have a warranty service (the no additional charge kind hopefully).

 

JD,

See the attached photos with red circles and boxes when reading this post.

The following components were replaced (with values) on your circuit board:
C1: 10µF, 50V See Note 1
C2: 47µF, 35V See Note 2
C3: 1,000µF, 16V See Note 3
C4: Values unknown.
C6: Values unknown.
C9: Not photographed.
C11: Values unknown.
C12: Not photographed.
C13: Not photographed.
C16: Values unknown and capacitor is not properly sized. See Note 4
C17: Values unknown and capacitor is not properly sized. See Note 4

Note 1: Board shows scars from leaked electrolyte – may not have been properly treated. Otherwise, it could just be a shadow from the angle.

Note 2: The capacitor is blurred and is hard to read the markings. It looks like 47uF and 35V. Voltage rating is higher than the original component. This may affect the discharge rate of the capacitor in the circuit. Please confirm.

Note 3: Voltage rating is higher than the original component. This may affect the discharge rate of the capacitor in the circuit. Furthermore, this capacitor is physically larger than the original, which may cause clearance issues with surrounding components.

Note 4: The form factor of C16 and C17 are "miniature" capacitors. Space between these 2 components is critical, which is why a smaller form factor was used. The values were blocked because of the angle and the speedometer face.

Other areas of concerns (may not be identified in red circles or boxes):

DA1: It is below C3 and its center leg needs to be further examined. Do NOT move/bend this component! It usually bears the brunt of electrolyte leakage from C3. It looks like the left leg was resoldered.

TR7: Examine the legs on this component because it suffers the same fate as DA1. Follow the same handling caution with DA1.

TR5: Located below TR7, the center leg on this transistor looks like it is missing solder.

CONN1 (Speedometer board connector): Several solder joints were replaced or repaired. This component is not normally a high failure item nor is susceptible to cold solder joints. The brown residue found around these joints is electrical flux that dried and cured for 25+ yrs. This type of flux is less toxic than others used in electronics so it is usually benign.

Tachometer circuit board: Examine the solder joints on IC1 and C5. The left leg of C5 looks like a cold/bad solder joint.

In summary, get closer photos on these capacitors and cited components. Use the zoom function and flashlight as required to really get in there! Many of these capacitors are blurred and their values cannot be easily read. Additionally, pay attention to the legs of each component. I'm looking for anomalies on solder joints – the union between the component leg and the circuit board. A cold or bad solder joint, like the one observed on C5 (Tachometer board) causes all sorts of electrical gremlins!

While we wait until you are situated to measure the wires in your car, please post up more photos of these suspect areas. These areas may not be the root cause of your current problem but they could potentially contribute to tolerance stacking errors.

Furthermore, hold off on contacting the repair shop for potential warranty work until we inspect the speedo board more AND verify the car's wiring is ok. Then you can submit these findings to the repair shop with 100% certainty.

Does all this information help?

 

Mugen,

I'm surprised to learn that there isn't an electronics repair shop in Japan that would provide help. I am shocked to hear that it will be cheaper for you to send the speedo fto the US for repair and then back to Japan. Nonetheless, I hope that you have a successful repair of your speedo. I believe the Mazdaspeed speedo uses the same electronics on the main speedo board. The only difference is the speedo face. There may be a difference in the LCD for the odometer but I haven't looked at a Mazdaspeed speedo in a while!

Based upon my observations and experience with the FD speedo, it takes several attempts to fix all of the problems when the problem is not immediately addressed.. Usually, replacing the electrolytic capacitors will suffice but the owner must act fast! The faster one replaces the bad components then the less damage to surrounding components are observed.

IMHO, all FD owners should remove and inspect their speedometer boards to assess any capacitor leakage. The sooner that is addressed then the more reliable their speedo and odometer become.

To answer your question, I don't think JD has verified ground wires yet. He is preparing for such an endeavor. And thank you for the compliment! I am one of a small handful of FD owners who successfully repaired the FD speedo. That is why I curate these speedo threads.

I do offer a word of advice when sending out a speedometer for repair. What test method does a company use to repair an FD speedo? What functions are they testing? As you know, the FD speedo is a rare bird with no schematics or troubleshooting matrices. The speedo board processes tach, vehicle speed, cruise control, auto trans, and water temp information and therefore requires unique testing procedures. For these reasons, it is wise to be wary of a company who claims, "we test the full functionality of the speedometer." Again, based on my experience, the most effective way to test a repaired FD speedo is to install it on the vehicle.

Bottom line is that a person must feel confident in a repair center's ability to fix the FD speedo. I know that others members had great experiences with repair shops fixing their broken speedos.

 

Tbh even if I did find a shop here I wouldn't trust them with it. When I resolved my issues with the OEM meter i didn't give it long tryout for other opportunities for failure, since I traded up for the mazdaspeed one (although I probably did damage it doing practice experiments on the side...I could probably still repair it with some free time). I got lucky I snagged MS meter cheap, but other (even non-functioning ones) are riduclously expensive. They're upwards of 1500 USD. My meter troubles aren't as bad as Sir Johns, its just the needles which still work but stick on cold starts. I'd much rather that instagram guy do it than some of these guys here. Never believe the hype the media shows about Japan lol...good or bad.

 

Having a hard time with my homework to find out about that 2B pin on the Apexi Power FC. I reached out again to Banzai to ask for a bit of guidance-sent photos and schematic. No response. Any ideas of where to go on the Apexi? I also contacted a guy who can help with pin remove and repair on the 3 series clips for the back of the cluster. The question becomes where would I reconnect the wires that have been jumped in to power the gauges on the pillar? Just need a bit of direction to know which way to go. Thanks, JD

 

JD,

Would you kindly post the highlights of our troubleshooting session on Sunday? This will help you establish a good baseline and document the repair of your tach & speedo. Furthermore, it will help other members in the future to follow the a similar troubleshooting matrix.

Do you have this patch harness going from your PowerFC to the car's wiring harness? FD Patch Harness

Based upon my research and the PowerFC FAQ by DaleClark, the PowerFC ECU is very similar to the stock ECU. It differs in some ways while similar in many others. If you look on Pg 10 of Dale's FAQ (PowerFC FAQ), there are 4 pins that should be removed. These are all emissions related. Therefore, the pin layout between the PowerFC and the stock ECU will be the same sans EGR, AWS, & Split air bypass. There is no need to mess with these wires unless there is another problem.

With that being said, let's shift gears into the repair of that cut wire. For the time being, leave the wires disconnected from your tach screws. You may lose the functionality of the additional gauges but will regain the tachometer.

Although outside of the scope of this thread, I would also like to see how those additional gauges are connected. There may be other wires concealed by those additional gauges. Post photos of those additional gauges. It may become necessary to trace the wires going to/from those additional gauges. Once the tach is repaired then we can address the additional gauges.

Remember, there's a lot going on here. We need to stay focused on the task at hand. Getting your tachometer to work is the main focus of your FD's problem.

 

@johnd08,

Want to see how you are doing with your FD and the wiring issue. How is your homework coming along?

 

^ George! Saw you in this thread. Haven't forgotten about you. Will connect soon.

 

George, I am just back in town and back to work from a week in Northern Michigan Where I got to play for a day but then work remotely while North. Not sure how many folks out there are familiar with Northern Michigan, but Harbor Springs & Petoskey on Little Traverse Bay is a beauty. Two of my brothers and I bought the rest of the family out of a family cottage sitting up on a bluff overlooking the Bay. It is truly one of the most restful and beautiful places you can imagine-but, I digress.

Ok, here is a re-cap of what I accomplished with George a couple of weeks ago. Very generously George set a time on a Sunday for me to call him to trace wires and see if we could determine if wiring was the issue with my instrument cluster and primarily my Tachometer. If you remember, I had sent the instrument cluster out to Atlanta Speedo for repair. Upon return, the Tach worked for about 5-10 minutes before not working again. So, with wiring diagrams in hand along with an electrical multi meter I followed George's lead tracking down wire after wire to determine where the problem was. Everything checked out until we got to the very last wire. Coincidentally this last wire was to lead directly to the tachometer and when I went to trace its connection I found that it had been cut and spliced into a connection that I can only guess goes to either a temperature gauge or boost gauge located on the driver side pillar. I have no idea if this is a typical tie in for power or who determined to cut this wire- but there you have it.

So, today I have some new photos to post that hopefully provide a better view of the circuit board. Next weekend I am planning on doing the wire repair, although I would like to have a plan for the gauge connection that is currently located at the cut. Would one of the gauges require some type of Tach signal in order to show boost or ...? I just don't have a clue. If the gauges need power supply for lighting or something simple I could rewire from the cigarette lighter which I don't use or need anyway. I would like to address that if possible so I dont have to disassemble the cluster again.

Ok, photos to follow.

 

So, let me know if these photos are any better for what you are looking for?

 

One more thing, regarding the Apexi Power FC, I have no idea where to turn for help on this control. I contacted a local speed shop-they work primarily on Hondas and Subaru and they could not direct me anywhere. The book I have for the Apexi is all in Japanese. So, I am open for suggestions.

 

John, retrace your steps. No wires from the harness lead directly to the tach. Power ground and signal are all provided from the speedo board. I’ve repaired hundreds of these and can confidently say your issue isn’t with the wire you are focusing in on.

 

Zensation, Ok, but I need a bit more guidance than that if you would please. If you scroll up to one of my photos you can see a yellow and a white wi


re connected to the back of the cluster. on re-assembly these two wires plug into a connector that has been patched in to pin 3Fon the back of the cluster. The wiring diagram relates pin 3 F to the tach-I will see if I can copy the diagrams and post so that you can see the connection. Perhaps you are already familiar with the path. Are you saying that the cluster may need another look vs. the wiring connections? I was thinking that I am going to replace and reconnect the clipped wire at 3F this weekend and look for an alternative power source for the 2 wires coming into the cluster as they were added after the fact anyway. I am wondering why they were connected at that particular spot to begin with-there must be some reason why the connection is made there?

 

I will share what I can. I was contracted to reverse engineer the circuit for a manufacturing company and most of the helpful info is covered under NDA......however I will say this and no one here has uncovered this yet, but that white wire is spliced into the tach signal from the ECU..this signal is pulsed high by the ECU at a particular frequency corresponding to the RPM of the motor obviously. however, the signal is passed through the speedometer board where the signal is conditioned by an optical comparator and actually INVERTED to a ground reference pulse. It is imperative to not bypass that conditioning by splicing directly into the harness wire i have replaced many tach motors with fried coils because of this improper procedure. what it looks like happened is the previous owner was having cluster issues and tried this to fix it. it works temporarily for destroying more stuff.

 

@johnd08,

I haven't forgotten about you. I've been very busy with work. Will comment on your photos shortly. Please don't forget to post pictures of the tach board. Please pay close attention to the spots that were highlighted in post #259.

In case you overlooked my post about the PowerFC, here it is again:

Based upon my research and the PowerFC FAQ by DaleClark, the PowerFC ECU is very similar to the stock ECU. It differs in some ways while similar in many others. If you look on Pg 10 of Dale's FAQ (PowerFC FAQ), there are 4 pins that should be removed. These are all emissions related. Therefore, the pin layout between the PowerFC and the stock ECU will be the same sans EGR, AWS, & Split air bypass. There is no need to mess with these wires unless there is another problem. Furthermore, you can use the FSM & WDM for ECU inputs and outputs.


@zensation,

Based on earlier research (refer to Posts 1 - 3 in this thread for relevant links & conversation), the tach signal runs through a compartor circuit on the speedo board. This comparator is part of an op amp that independently processes both tach and speedometer analog signals. These processed signals are then sent to the respective driver ICs for each stepper motor - one for the speedometer needle and the other for the tachometer needle. Could you elaborate more on that? What optical circuit are you referring to - the Vehicle Speed Sensor (VSS)? I was under the impression that the VSS circuit operated on magnetic induction. Is that a correct observation?

Additionally, when I helped JD measure resistance on the wire harness, the only signal that was open was Pin 3F (C1-01 3F). A visual inspection revealed that wire was physically cut. All other connections between the ECU, relevant sensors, and Connector C1-01 (3-Series) checked good. Could there be other issues lurking? Maybe. The flex print wires would need to be tested to remove any doubts. But I believe that cut wire which leads to Pin 3F should be repaired before we continue further.

I agree with zensation: the addition of jumper wires to your tach is not a long-term solution to fix a broken tachometer or to splice in additional gauges. There may be a short-term gain but will result in a long-term loss from a poorly conditioned signal.

One final parting thought for JD: There could be a chance that the wire mod to your instrument cluster may have damaged your speedo board after it was repaired. Going back to the short-term gain concept, the tach was probably not working because of bad caps on the speedo board. So it was bypassed with those wires. The tach may have worked but was "quirky". Then you decided to send out the speedo for repair. Once it returned, you installed the instrument cluster to the car and reconnected those additional wires without fully understanding their purpose. During the initial warm up, the gauges worked but failed once you returned several minutes later. How extensive is that damage? We will not know until the circuit is tested again.

As stated earlier, let's focus on repairing that broken wire to Pin 3F, leave those parasitic wires disconnected, and get a closer examination of the solder joints on the tach circuit board. How does that sound?

 

sry freudian slip, im working on robotics vision systems right now and had optical comparators on the mind. Correct its just a 'comparator' as a full vision system will certainly neither fit on this board nor be useful anyway yeah the op amp effectively inverts the signal and thus i've seen damage on several and had to replace several blown coils in the tach motors with a high correlation to the 'speedo board conditioning bypass surgery' if you will.

 

Gen2n3 (George) Like you I have been extremely busy at work and have not been able to dedicate the time I need to work on the car. What is extremely frustrating for me is that I don't really understand where you have me going or the conversation with other members like Zen who is talking like you about things I don't even relate to. Example: I can do simple things like rebuild brake calipers or corner balance suspension. I cannot work on the engine or hook up a computer and program for fuel or whatever else one does with their car hooked to a laptop. With that said, I have a fellow who will help me try to repair 3F this weekend. I have reposted photos for your review so that ball I think is in your court. I also contacted another member for Apexi guidance and input on another thread-he's replied, but I don't really understand the electrical aspect of his direction or explanation-sorry. My expertise is woodwork. If you need something explained for a process in woodwork I could certainly help out-this is Greek to me.

 

An update in my continuing saga of converting my 93 RX7 to a dedicated track car. In the last episode I worked closely with Gen2n3 (George) to track /trace wires down to see what was up with my instrument cluster that was not working properly. At the end of a long session of wire tracing we discovered that the wire to pin 3F was physically cut and felt that this was the primary culprit in the non functioning tachometer dilemma. In the meantime, there were still unanswered questions about the viability of my tachometer repair done by Atlanta Speedometer and George was reviewing photos I had posted. Along comes Zensation who has considerable knowledge and experience with the instrument cluster. Simple solution, I send my cluster off to him and he will repair. So, I send it off, get it back, repair wire and connection at 3F and reinstall the cluster-start the car up and the Tack is flat dead in the panel-no lights, no bounce, nothing. At this point I am over it. I am not going to pull the panel again and go through all of that. I figure I will just run this year trying to use the hand held control from the Power FC to see where my rpm's go and the hell with it. I drop the car off at my mechanics shop for some final tuning and call it a day. So now the mechanic has the car for tuning and we set a date to put the car on the dyno which was yesterday, Friday the 7th. I have to load the car into my trailer and take it to the dyno-I get in and start it up and lo and behold the Tach starts working! The only thing I can figure is that when I started it up after reinstall the Power FC hadn't recognized or reinitiated the connection?!? Right now, I am a happy camper, but what a crazy journey. Plenty more to come, dyno day was a bust as there are now fuel mapping issues. Back on the Dyno this coming Tuesday and we will see what we will see. Thanks to George and Zensation for all of your help on the Instrument cluster.