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Happy to lend advise and wish you best of luck on your repairs.
Before you order TR5, make sure you visually inspect all the components on the board, especially other capacitors. From my personal experience, be careful when replacing Zener diodes (ZDx). Some Zener diodes have the same part number while others differ. Always verify Zener part numbers against spec sheets (found online). You may have to search for a Zener by specification from DigiKey or similar sites. Don't treat a Zener (or other diodes) like a fuse. For example, if the diode is rated at 6.3V then replace it with the same voltage rating. After you identified all components that need to be replaced, then place your oder on DigiKey.
CAUTION: Do NOT replace a Zener (or other) diode with a higher voltage rating because damage to the circuit board may occur!
Additionally, observe the polarity on diodes. In a schematic, a diode looks like this: -->|-- Physically, the diode will have a black line (look at your photo with ZD3). The black line on the diode corresponds to the schematic symbol. The "arrow" on the schematic points to the negative (-) material and the black line indicates the same (negative material/leg).
If possible, take before & after photos of the repair and list part numbers of replaced components. Please report back to this thread and share your experience. It may help another member in a similar circumstance.
You can PM me if you need further help. Again, best of luck in your repairs!
Cheers,
George
Anytime. Although I don't know why the .2 is smaller either. Do you plan on replacing C11? It doesn't look swelled or leaking. BTW, look at diode D5 in the upper left corner - you can see the schematic symbol underneath it and note the silver ring on its right side. That points to the negative (-) side.
I've ordered the 2.2 and another 1000 just in case I over heated it... I'm going to replace those 2 then see what happenes.....Fingers crossed. I see what you are talking about but have no idea which way it is supposed to point and I haven't touched that one.
Glad to see I'm not the only one struggl;ing with this. My ODO is still hit or miss for working. It never fails to come on eventually, but every once in a while it will take a few miles to pop on. Other times it's on immediately and still others it takes a tap on the dash to get it working sitting in the driveway during warm-up.
The weird thing is... once it turns on it's good for the rest of the drive!
All the caps have been replaced twice. Once by me and another time by southern electronics to no avail. Finally, I re-soldered a bunch of the other components and it finally started working intermittently. I never thought to look at the transistors or other components; I just looked for cold solder joints. I guess that's the next step if it gets worse again.
Another member reported that he needed to solder the top (component) side of his caps to permanently fix his odometer. He suggests the board is multi-layered and the solder on the component side of the board completes the circuit. That should be around post #76.
Admittedly, my odo repair worked for a period of time but is now intermittent. I tried the quick fix of disconnecting the positive battery terminal. It worked briefly but my odo has a mind of its own now. I need to examine the board again for solder joints.
Another member reported that he needed to solder the top (component) side of his caps to permanently fix his odometer. He suggests the board is multi-layered and the solder on the component side of the board completes the circuit. That should be around post #76.
Admittedly, my odo repair worked for a period of time but is now intermittent. I tried the quick fix of disconnecting the positive battery terminal. It worked briefly but my odo has a mind of its own now. I need to examine the board again for solder joints.
Cheers,
George
I appreciate the reply... I think that other member was me
Sounds like we're having the same problem!
I am attaching the PDF spec sheet for the MSM6544 display driver, IC7. My driver says M6544 with no MS in front of it, but this is the closest I can get... maybe they're the same? Pin count matches.
EDIT: Also attaching data sheet for IC5 (NEC D75108GF), which I believe is the chip for the trip computer and has on-board memory for mileage. I think this chip feeds inputs to the odometer display chip.
I don't know what the display driver chip for the trip display is yet, but I don't think it's the same driver as the ODO display. The ODO display driver, IC7 is only capable of outputting 42 segments. On the ODO there are 6 digits x 7 segments = 42 segments total. The trip display obviously needs more segments and could be driven directly from the trip computer chip, IC5. IC5 has outputs that can directly drive LED's.
Re-cap:
ODO display driver: IC7, OKI M6544, 42 segment display driver
Trip computer: IC5, NEC D75108GF, has on-board memory and can drive LED's
Possible trip display driver: IC5, NEC D75108GF ... same chip as trip computer
Because both the trip and ODO displays go out at the same time, this leads me to believe that the problem isn't the display driver (IC7), but an issue with the trip computer (IC5) or LCD display itself.
The issue could be:
A) a bad connection/component not providing power/ground to the trip computer (IC5 pins VDD/VSS) or LCD display
B) failing trip computer chip (IC5)
C) failing LCD display
D) something much simpler: has anyone tried replacing the backlight bulb for the LCD display? I wonder if the LCD is even visible with this bulb out and we might just need a new backlight? I've had bad bulbs work intermittently before when the filament re-connects itself to the other side.
To rule out option D possibly and to also help with trouble shooting is the fact that the cruise doesn't function correctly when it isn't working. If it was just a lighting issue I wouldn't think the cruise would be affected.
If it weren't for my cruise acting funny now I probably wouldn't have messed with it but I hate driving without cruise.
Mine is still a no go......My car is not running right now so I am only able to check it by turning the ignition on.
I appreciate the reply... I think that other member was me
Sounds like we're having the same problem!
I am attaching the PDF spec sheet for the MSM6544 display driver, IC7. My driver says M6544 with no MS in front of it, but this is the closest I can get... maybe they're the same? Pin count matches.
EDIT: Also attaching data sheet for IC5 (NEC D75108GF), which I believe is the chip for the trip computer and has on-board memory for mileage. I think this chip feeds inputs to the odometer display chip.
I don't know what the display driver chip for the trip display is yet, but I don't think it's the same driver as the ODO display. The ODO display driver, IC7 is only capable of outputting 42 segments. On the ODO there are 6 digits x 7 segments = 42 segments total. The trip display obviously needs more segments and could be driven directly from the trip computer chip, IC5. IC5 has outputs that can directly drive LED's.
Re-cap:
ODO display driver: IC7, OKI M6544, 42 segment display driver
Trip computer: IC5, NEC D75108GF, has on-board memory and can drive LED's
Possible trip display driver: IC5, NEC D75108GF ... same chip as trip computer
Because both the trip and ODO displays go out at the same time, this leads me to believe that the problem isn't the display driver (IC7), but an issue with the trip computer (IC5) or LCD display itself.
The issue could be:
A) a bad connection/component not providing power/ground to the trip computer (IC5 pins VDD/VSS) or LCD display
B) failing trip computer chip (IC5)
C) failing LCD display
D) something much simpler: has anyone tried replacing the backlight bulb for the LCD display? I wonder if the LCD is even visible with this bulb out and we might just need a new backlight? I've had bad bulbs work intermittently before when the filament re-connects itself to the other side.
Alex,
Oh, funny that I quoted one of your earlier posts!
I agree with Blacksi (Mark) that option D (or Option C) may not be the root of your issue. Do you have any problems with Cruise Control when your odo is out? If you do have cruise problems then the LCD backlight or LCD display is not the problem. Besides, do you see an orange backlight when the ignition is switched on?
Perhaps Option A is more the root of your problem (and mine)? Have you given the circuit board a good look at solder joints? I need to examine my board rather well. Perhaps there are other caps that may look good but are out of spec?
My concern with Option B: If IC5 is bad then a new one is soldered in place then how would the proper mileage be input? I vaguely remember seeing a company to offer such a service but is expensive.
In summary, I suspect there are a few capacitors that may need replacement along with re-soldering poor/questionable solder joints.
*break*
Mark, have you made any new progress on your circuit board?
has anyone had any luck figuring out how to fix the jumpy tach issue? im assuming this is a whole different can of worms, but im wondering if there are maybe some of the same type capacitors on the tach board that burn out in the same way
has anyone had any luck figuring out how to fix the jumpy tach issue? im assuming this is a whole different can of worms, but im wondering if there are maybe some of the same type capacitors on the tach board that burn out in the same way
Today, I examined my Speedometer-Odometer circuit board because after the initial capacitor replacement (C3) it worked. Then after a few months of use, the odometer started to blank out. I followed the recommendation of disconnecting the Positive (+) battery cable then reconnect it. That worked for a few times but the odometer would sporadically come on then cut out. It now remains blanked out.
I desoldered C3, that's the 1,000uF 6.3V capacitor, removed, then reinstalled and soldered it back in. After reassembly of the cluster, it was tested on the car. The odometer did NOT return. Rats!
A visual inspection on the remainder of the caps and other solid state components proved no unusual results. In the mean time, I ordered replacement caps previously cited in this article. I also added C11, which is a 2.2uF 50V cap under DigiKey P/N: P13462-ND.
I also want to replace C9 but cannot confirm its capacitance rating. It's labeled 50V R33 BP. The closest match on Google was a 33uF 50V radial capacitor. Using these specs, DigiKey gave me an equivalent part number of P10320-ND (manufacturer P/N: EEU-FC1H330). If the other caps do not fix the blanked out Odometer, then I may replace C9. But, I'd like to confirm its specs. Has anyone replaced C9 before?
In short, I ordered replacement capacitors from DigiKey. This is what was ordered:
Qty // DigiKey P/N // Description // Customer Reference
2 // P10199-ND // CAP ALUM 1000UF 20% 6.3V RADIAL // C3
3 // 493-1890-ND // CAP ALUM 10UF 20% 50V RADIAL // C1, C10, C12
1 // P5539-ND // CAP ALUM 47UF 20% 25V RADIAL // C2
3 // 565-1332-ND // CAP ALUM 1UF 20% 50V RADIAL // C4, C6, C13
1 // P13462-ND // CAP ALUM 2.2UF 20% 50V RADIAL // C11
1 // P10320-ND // CAP ALUM 33UF 20% 50V RADIAL // C9
This thread proved to be very helpful! I pulled my gauge cluster and fixed it in the last couple of days. It looks like my issue was a little bit different than what others have discussed.
Problem - No ODO reading. Cruise was working and wasn't hunting.
Issue - ZD4 Zener diode was smoked. It got really hot and left burn marks on the plastic and one of the connections was burnt off and wasn't making contact to the board.
Fix - Replaced the Zener diode from Radio shack and replaced C3 capacitor (didn't look bad), because I had the part and it was easy to get to. Cleaned everything up and put back together.
A couple of notes -
1. If you do this, be prepared to break your gauge cluster hood. Mine was stuck to the dash and even being very gentle didn't save it from breaking.
2. In most cases, you probably don't need to de-solder and re-solder the gauge face from the board. I had plenty of room to fix my issues without doing the extra work and having the extra risk of messing something up.
TravAZ, Good to see that you repaired your speedometer board. After you replaced ZD4 and C3, did your odometer come back to life? Other members, myself included, report that after repairs are made then the odometer blanking returns. If it was fixed, keep this thread in mind a few months of use. Would you kindly provide feedback after a few months, be it positive or negative experiences?
I also have some observations about your circuit board:
1. One eyelet of ZD4 looks heavily scorched. The hole looks a lot bigger too. Was the eyelet still intact?
2. How does the solder cup look from the backside of the board? That larger solder cup must not contact the other solder cups besides it. See photo.
3. What is the Zener diode part number that you used from Radio Shack: 276-0565?
3.a. Thanks for taking a photo of the replacement Zener diode package that also shows its specs.
3.b. How did you know what specs to use for this diode?
4. Reinspect the solder joints around TR7 and DA1, ZD5, ZD7, and ZD3. They look blackened, charred, or tarnished & deformed. This could cause a failure in the future. Replacement of the solder in those joints may be necessary.
5. I compiled a list of components from this board here: https://www.rx7club.com/3rd-generati...nents-1112010/. You are welcome to contribute to that list of components.
Thanks again for sharing your experience & I wish you the best of luck with your repair!
Cheers,
George
Red cap points to the solder joint of ZD4. Note its separation from ZD5 and ZD7's solder joints. It is normal for the solder joints of ZD5 & ZD7 to touch. They share the same electrical connection.
Today, I examined my Speedometer-Odometer circuit board because after the initial capacitor replacement (C3) it worked. Then after a few months of use, the odometer started to blank out. I followed the recommendation of disconnecting the Positive (+) battery cable then reconnect it. That worked for a few times but the odometer would sporadically come on then cut out. It now remains blanked out.
I desoldered C3, that's the 1,000uF 6.3V capacitor, removed, then reinstalled and soldered it back in. After reassembly of the cluster, it was tested on the car. The odometer did NOT return. Rats!
A visual inspection on the remainder of the caps and other solid state components proved no unusual results. In the mean time, I ordered replacement caps previously cited in this article. I also added C11, which is a 2.2uF 50V cap under DigiKey P/N: P13462-ND.
I also want to replace C9 but cannot confirm its capacitance rating. It's labeled 50V R33 BP. The closest match on Google was a 33uF 50V radial capacitor. Using these specs, DigiKey gave me an equivalent part number of P10320-ND (manufacturer P/N: EEU-FC1H330). If the other caps do not fix the blanked out Odometer, then I may replace C9. But, I'd like to confirm its specs. Has anyone replaced C9 before?
In short, I ordered replacement capacitors from DigiKey. This is what was ordered:
Qty // DigiKey P/N // Description // Customer Reference
2 // P10199-ND // CAP ALUM 1000UF 20% 6.3V RADIAL // C3
3 // 493-1890-ND // CAP ALUM 10UF 20% 50V RADIAL // C1, C10, C12
1 // P5539-ND // CAP ALUM 47UF 20% 25V RADIAL // C2
3 // 565-1332-ND // CAP ALUM 1UF 20% 50V RADIAL // C4, C6, C13
1 // P13462-ND // CAP ALUM 2.2UF 20% 50V RADIAL // C11
1 // P10320-ND // CAP ALUM 33UF 20% 50V RADIAL // C9
More to follow when the parts arrive.
Cheers,
George
Here's a good update on Post #190:
I received the above components from DigiKey yesterday. They had fast shipping on 1st Class mail! I was surprised when the package arrived.
Between yesterday and today, I replaced capacitors C1, C2, C3, C4, C6, C11, C12, & C13. A good portion of these capacitors were difficult to remove because of stubborn solder. I used a de-soldering iron to remove the old solder. Typically, the negative lead of the capacitor was much more difficult to remove. The best way to remove them was to cut them away from the board. Afterwards, the de-solder iron was placed on the top side of the lead and extracted the solder and remaining lead from the eyelet.
I also had to bend the leads of all the caps (minus C3) out because they wouldn't fit otherwise. The best way to do this is to grab a pair of needle nose pliers and bend a lead out 45* near the base of the capacitor. Then slide the pliers down a tad to bend the lead back inwards 45*. Then repeat for each leg. Where you place the inward bend will determine the height of the capacitor. See the photo.
It doesn't take long to put each 45* bend in each lead.
When soldering the capacitors back into place, I ensured that solder flowed to the top of each lead. You should see a small cone shape at the backside AND the front side of each lead's eyelets. If you don't see that then desolder that joint and then reapply new solder. For anyone who may be electrically challenged, use solder flux. It ensures solder will flow to the top of each eyelet. I used the paste type of flux and put a small dab of it on the top side and bottom side of each eyelet. Once all capacitors are installed, clean each joint with isopropyl alcohol.
Afterwards, the speedometer was soldered to the circuit board and then the instrument cluster was reassembled. The cluster was tested in the car and....PRESTO! The odometer display came back to life. The instrument cluster was reassembled and then installed into the car. I took it for a test drive and verified that after 1mi, the odometer and tripometer incremented by 1.
One unusual thing to note, there is a slight delay in the odometer's appearance when the ignition is set to ON. The tripometer comes on nearly instantly but there is a noticeable delay with the odometer.
As another side note, the "Add Coolant" light and buzzer are constantly on. That didn't happen before this project started. After the car cools down and pressure is relieved, I'll verify the coolant level. I hope that there are no hidden gremlins in my newly fixed speedometer circuit board!
I'll keep my fingers crossed on this repair but if something else happens, then I'll diligently report my findings.
Yes, it was burnt badly and the hole was larger as you pointed out. I had to make sure I soldered carefully on both sides so that I had good contact with the board. The copper on the board was burnt back, so I had to solder to the left of the hole to make sure I had good contact on what was still there.
When I powered it back up, my trip was at 0, but the mileage was correct at 92,000 miles.
Some of the other capacitors may look suspect in the picture, but they look good in person and everything was cleaned with alcohol and cotton swabs before re-installing.
The Zener diode is the only one that Radio Shack stocks at their stores. I went with this one because it was available locally and others have used it with good success.
Nicely done! Thanks for the skinny on the Zener Diode and the added photos. Did you remove the white retaining clip to the ribbon cable connector? Was it reinstalled or how do you retain the ribbon cable?
The hood should not have broken that way. Do you know what caused it to break? Could the hotter AZ temps or constant sunlight exposure caused it to become brittle?
Gen2n3 Congrats on getting yours working! I put mine on hold and its still on the kitchen table....It still didn't work after replacing other parts. I may give it one more try and order some others I didn't replace like the r33 one you mentioned...
So my friend already repaired 2 dead odmeters successfully for me . The 3rd one is a bit odd. , he replaced all caps and a lot of other surface components . Now the odmeter works for about 30 minutes but after that the odmeter and the speedometer stops working . After switching it off for 20 minutes it works again for about 30 minutes . Any idea what it could be ?
03-06-17, 11:02 AM
