Heineken
20-07-2020, 06:38 PM
Failing capacitors at the gauge cluster of the NSX is a serious topic. First signs are a non-accurate speed indication or a permanently lit brake light warning even though bulbs and wiring are OK. The leaking acid near the warning indicator circuit can cause a short and even potentially lead to a fire. Same as with the other capacitor issues a replacement should be considered before the unit fails.
From a soldering point of view, replacing the capacitors on the gauge cluster isn't too complicated. The PCB is rather standard and there are no large copper areas that would require strong tools to get up to temperature. There are other things to consider, though. We'll come across these while talking about the steps for the replacement on my 1997 JDM AT gauge cluster.
If the cluster hasn't been re-calibrated yet than the readings should still be accurate after the exchange. In these cases it should be sufficient to check the speedometer after re-installation into the car using a mobile phone. Once the state of calibration is unknown, test equipment (a signal generator or gauge tester (http://www.nsxcb.co.uk/showthread.php?15829-Gauge-Cluster-Calibrator)) is needed to re-calibrate the speed and potentially RPM gauges.
After removal of the cluster from the vehicle (there's a nice write-up at nsx-prime (http://www.nsxprime.com/forum/showthread.php/90599-DIY-Gauge-Cluster-Tripmeter-Removal?p=839214&viewfull=1#post839214)) the unit can be examined in detail. The first item to remove is the opaque white plastic cover at the back. To do so, unscrew the large black bulb holder by turning it about a quarter of a revolution and pulling it from the PCB followed by removing the cable from its support points.
13963
To detach the cover, unscrew all the yellow screws. The zinc- and silver coloured ones don't need to be touched yet. Now unhinge the cover from the white tabs on the borders of the casing and put the cover aside.
By the way, the blue tape on the top covers the variable resistors for calibration of the RPM and speed gauge which will be covered at a later point.
13964
Next have a look at the PCB with the silver-coloured screws holding it in place and here comes the first warning:
Those silver coloured screws electrically connect the PCB to the gauges on the housing (fuel, voltage, temperature, oil pressure, speed and RPM).
Removal is of no risk but re-installation is a delicate job which we will cover when we reach the corresponding part.
All bulbs can remain in the PCB. To separate the PCB from the housing it's necessary to disconnect the cables between the two PCBs as well as the trip and odometer stepper motor connection. This can be a little tricky as they are a tight fit. A set of dentist hooks is helping but should be used with caution.
13972
As mentioned in the entry about the gauge cluster bulb replacement (http://www.nsxcb.co.uk/showthread.php?15838-Gauge-Cluster-Bulb-Replacement) it's advisable to replace all the illumination bulbs as well as the 'D' indicator on AT vehicles after about 100.000 km. They are typically darkened considerably at this mileage and the risk of failure is increasing.
Now the most time consuming part starts. The selection of replacement capacitors. Due to the nature of the failure I decided to focus on the wet electrolyte ones on the board and trying to replace them with dry (Aluminium Polymer) ones. As these are analogue circuits and two special capacitor types are to be considered (low leakage and bi-polar) it's not possible in all cases.
Additionally, the correct capacitance, sufficient voltage rating and size of the replacement has to be considered. When offered with several alternatives, the one with the longest life time was chosen:
Left PCB (component view)
Name
Original
Replacement
C1
2200 μF 16 V 105 °C ↨ 20 mm ∅ 12 mm RM5
Nippon Chemicon KMG (wet electrolyte)
2200 μF 16 V 105 °C 20,000 h ↨ 21.5 mm ∅ 10 mm RM5
United Chemicon PSG (dry electrolyte)
C3
3.3 μF 50 V 105 °C ↨ 10 mm ∅ 5 mm RM2
Panasonic [M] NHE (GE) (wet electrolyte)
3.3 μF 50 V 105 °C 10,000 h ↨ 12.5 mm ∅ 5 mm RM2
United Chemicon LE (wet electrolyte)
C5
2.2 μF 50 V 105 °C ↨ 10 mm ∅ 5 mm RM2
Panasonic [M] NHE (GE) (wet electrolyte)
2.2 μF 50 V 105 °C 10,000 h ↨ 12.5 mm ∅ 5 mm RM2
United Chemicon LE (wet electrolyte)
C12
10 μF 50 V 105 °C ↨ 10 mm ∅ 5 mm RM2
-unknown manufacturer- (wet electrolyte)
10 μF 50 V 105 °C 10,000 h ↨ 12.5 mm ∅ 5 mm RM2
United Chemicon LE (wet electrolyte)
C17
33 μF 50 V 105 °C ↨ 10 mm ∅ 5 mm RM2
Nippon Chemicon KMG (wet electrolyte)
33 μF 50 V 105 °C 10,000 h ↨ 12.5 mm ∅ 6.3 mm RM2.5
United Chemicon LE (wet electrolyte)
C18
47 μF 16 V 105 °C ↨ 10 mm ∅ 5 mm RM2
Panasonic [M] NHE (GE) (wet electrolyte)
47 μF 25 V 105 °C 10,000 h ↨ 12.5 mm ∅ 5 mm RM2
United Chemicon LE (wet electrolyte)
C19
33 μF 10 V 85 °C ↨ 10 mm ∅ 5 mm RM2
Nippon Chemicon LLA (wet electrolyte)
⚠ Low Leakage
33 μF 25 V 105 °C 1000 h ↨ 12 mm ∅ 5 mm RM2
Nichicon UKL - Low Leakage
C20
10 μF 16 V 85 °C ↨ 10 mm ∅ 5 mm RM2
Nippon Chemicon LLA (wet electrolyte)
⚠ Low Leakage
10 μF 25 V 105 °C 1000 h ↨ 12 mm ∅ 5 mm RM2
Nichicon UKL - Low Leakage
C21
100 μF 16 V 105 °C ↨ 10 mm ∅ 7 mm RM2
Panasonic [M] NHE (GE) (wet electrolyte)
100 μF 16 V 105 °C 10,000 h ↨ 12.5 mm ∅ 6.3 mm RM2
United Chemicon LE (wet electrolyte)
Right PCB (component view)
Name
Original
Replacement
C1
see Left PCB - C1
see Left PCB - C1
C3
see Left PCB - C3
see Left PCB - C3
C5
6.8 μF 25 V 105 °C ↨ 5 mm ∅ 3.5 mm RM2
Panasonic [M] -unknown series- (wet electrolyte)
6.8 μF 25 V 105 °C 3000 h ↨ 6 mm ∅ 6.3 mm RM2.5
Panasonic SEP (dry electrolyte)
C14
see Left PCB - C12
see Left PCB - C12
C15
47 μF 25 V 105 °C ↨ 7 mm ∅ 7 mm RM2
Nippon Chemicon KMA (wet electrolyte)
47 μF 35 V 125 °C 1000 h ↨ 6 mm ∅ 6.3 mm RM2.5
Panasonic SEK (dry electrolyte)
C17
47 μF 25 V 105 °C ↨ 10 mm ∅ 7 mm RM2
Nippon Chemicon KME (wet electrolyte)
⚠ Bi-Polar
47 μF 25 V 105 °C 1000 h ↨ 12.5 mm ∅ 6.3 mm RM2.5
Nippon Chemicon UEP (wet electrolyte)
C18
See C18 ↑
See C18 ↑
All the types above are available from digikey. In case your cluster's capacitors are identical feel free to use this shopping cart for an order: https://www.digikey.de/short/zbhfd5
De-soldering can be accomplished by means of de-solder wick or a manual de-solder pump. Using a vacuum unit is more comfortable, of course but not strictly necessary.
Soldering the new parts requires no special tools, a normally sized (~30 W) iron is sufficient, a temperature regulated one even better but not a must.
13960
13961
Now everything has to be put back together. In theory the same steps as during disassembly just in reverse order. Connecting the stepper motors is (again) a little fiddly but can be accomplished without special tools.
The most dangerous part is attaching the PCB to the housing by means of the silver-coloured screws. As mentioned before, they are responsible for the electrical connection of the gauges to the PCB.
Their threads are located inside the gauges and are easy to twist-off. Hair-thin wires are attached to them. If a twist-off happens they are very likely to snap.
This can be repaired but is a very delicate task and replacement gauges are expensive. To avoid any of this from happening it's best to follow these rules:
Insert and rotate the screws with your fingers until they are safely engaged.
Use a screwdriver and rotate the screw with two fingertips (not more) until the spring washer just starts to compress.
Tighten the screw further until the washer just reaches full compression, a few degrees more at maximum.
After all this has been accomplished successfully the unit can be installed back into the car.
13962
Check if all lamps light up, backlight is working, RPM and speed values are correct. If no adjustments have been made to the calibration potentiometers the display should still be sufficiently accurate. In any case, ensure that the displayed speed is not below the actual speed as this is illegal in most countries.
<< -- continued below -->>
From a soldering point of view, replacing the capacitors on the gauge cluster isn't too complicated. The PCB is rather standard and there are no large copper areas that would require strong tools to get up to temperature. There are other things to consider, though. We'll come across these while talking about the steps for the replacement on my 1997 JDM AT gauge cluster.
If the cluster hasn't been re-calibrated yet than the readings should still be accurate after the exchange. In these cases it should be sufficient to check the speedometer after re-installation into the car using a mobile phone. Once the state of calibration is unknown, test equipment (a signal generator or gauge tester (http://www.nsxcb.co.uk/showthread.php?15829-Gauge-Cluster-Calibrator)) is needed to re-calibrate the speed and potentially RPM gauges.
After removal of the cluster from the vehicle (there's a nice write-up at nsx-prime (http://www.nsxprime.com/forum/showthread.php/90599-DIY-Gauge-Cluster-Tripmeter-Removal?p=839214&viewfull=1#post839214)) the unit can be examined in detail. The first item to remove is the opaque white plastic cover at the back. To do so, unscrew the large black bulb holder by turning it about a quarter of a revolution and pulling it from the PCB followed by removing the cable from its support points.
13963
To detach the cover, unscrew all the yellow screws. The zinc- and silver coloured ones don't need to be touched yet. Now unhinge the cover from the white tabs on the borders of the casing and put the cover aside.
By the way, the blue tape on the top covers the variable resistors for calibration of the RPM and speed gauge which will be covered at a later point.
13964
Next have a look at the PCB with the silver-coloured screws holding it in place and here comes the first warning:
Those silver coloured screws electrically connect the PCB to the gauges on the housing (fuel, voltage, temperature, oil pressure, speed and RPM).
Removal is of no risk but re-installation is a delicate job which we will cover when we reach the corresponding part.
All bulbs can remain in the PCB. To separate the PCB from the housing it's necessary to disconnect the cables between the two PCBs as well as the trip and odometer stepper motor connection. This can be a little tricky as they are a tight fit. A set of dentist hooks is helping but should be used with caution.
13972
As mentioned in the entry about the gauge cluster bulb replacement (http://www.nsxcb.co.uk/showthread.php?15838-Gauge-Cluster-Bulb-Replacement) it's advisable to replace all the illumination bulbs as well as the 'D' indicator on AT vehicles after about 100.000 km. They are typically darkened considerably at this mileage and the risk of failure is increasing.
Now the most time consuming part starts. The selection of replacement capacitors. Due to the nature of the failure I decided to focus on the wet electrolyte ones on the board and trying to replace them with dry (Aluminium Polymer) ones. As these are analogue circuits and two special capacitor types are to be considered (low leakage and bi-polar) it's not possible in all cases.
Additionally, the correct capacitance, sufficient voltage rating and size of the replacement has to be considered. When offered with several alternatives, the one with the longest life time was chosen:
Left PCB (component view)
Name
Original
Replacement
C1
2200 μF 16 V 105 °C ↨ 20 mm ∅ 12 mm RM5
Nippon Chemicon KMG (wet electrolyte)
2200 μF 16 V 105 °C 20,000 h ↨ 21.5 mm ∅ 10 mm RM5
United Chemicon PSG (dry electrolyte)
C3
3.3 μF 50 V 105 °C ↨ 10 mm ∅ 5 mm RM2
Panasonic [M] NHE (GE) (wet electrolyte)
3.3 μF 50 V 105 °C 10,000 h ↨ 12.5 mm ∅ 5 mm RM2
United Chemicon LE (wet electrolyte)
C5
2.2 μF 50 V 105 °C ↨ 10 mm ∅ 5 mm RM2
Panasonic [M] NHE (GE) (wet electrolyte)
2.2 μF 50 V 105 °C 10,000 h ↨ 12.5 mm ∅ 5 mm RM2
United Chemicon LE (wet electrolyte)
C12
10 μF 50 V 105 °C ↨ 10 mm ∅ 5 mm RM2
-unknown manufacturer- (wet electrolyte)
10 μF 50 V 105 °C 10,000 h ↨ 12.5 mm ∅ 5 mm RM2
United Chemicon LE (wet electrolyte)
C17
33 μF 50 V 105 °C ↨ 10 mm ∅ 5 mm RM2
Nippon Chemicon KMG (wet electrolyte)
33 μF 50 V 105 °C 10,000 h ↨ 12.5 mm ∅ 6.3 mm RM2.5
United Chemicon LE (wet electrolyte)
C18
47 μF 16 V 105 °C ↨ 10 mm ∅ 5 mm RM2
Panasonic [M] NHE (GE) (wet electrolyte)
47 μF 25 V 105 °C 10,000 h ↨ 12.5 mm ∅ 5 mm RM2
United Chemicon LE (wet electrolyte)
C19
33 μF 10 V 85 °C ↨ 10 mm ∅ 5 mm RM2
Nippon Chemicon LLA (wet electrolyte)
⚠ Low Leakage
33 μF 25 V 105 °C 1000 h ↨ 12 mm ∅ 5 mm RM2
Nichicon UKL - Low Leakage
C20
10 μF 16 V 85 °C ↨ 10 mm ∅ 5 mm RM2
Nippon Chemicon LLA (wet electrolyte)
⚠ Low Leakage
10 μF 25 V 105 °C 1000 h ↨ 12 mm ∅ 5 mm RM2
Nichicon UKL - Low Leakage
C21
100 μF 16 V 105 °C ↨ 10 mm ∅ 7 mm RM2
Panasonic [M] NHE (GE) (wet electrolyte)
100 μF 16 V 105 °C 10,000 h ↨ 12.5 mm ∅ 6.3 mm RM2
United Chemicon LE (wet electrolyte)
Right PCB (component view)
Name
Original
Replacement
C1
see Left PCB - C1
see Left PCB - C1
C3
see Left PCB - C3
see Left PCB - C3
C5
6.8 μF 25 V 105 °C ↨ 5 mm ∅ 3.5 mm RM2
Panasonic [M] -unknown series- (wet electrolyte)
6.8 μF 25 V 105 °C 3000 h ↨ 6 mm ∅ 6.3 mm RM2.5
Panasonic SEP (dry electrolyte)
C14
see Left PCB - C12
see Left PCB - C12
C15
47 μF 25 V 105 °C ↨ 7 mm ∅ 7 mm RM2
Nippon Chemicon KMA (wet electrolyte)
47 μF 35 V 125 °C 1000 h ↨ 6 mm ∅ 6.3 mm RM2.5
Panasonic SEK (dry electrolyte)
C17
47 μF 25 V 105 °C ↨ 10 mm ∅ 7 mm RM2
Nippon Chemicon KME (wet electrolyte)
⚠ Bi-Polar
47 μF 25 V 105 °C 1000 h ↨ 12.5 mm ∅ 6.3 mm RM2.5
Nippon Chemicon UEP (wet electrolyte)
C18
See C18 ↑
See C18 ↑
All the types above are available from digikey. In case your cluster's capacitors are identical feel free to use this shopping cart for an order: https://www.digikey.de/short/zbhfd5
De-soldering can be accomplished by means of de-solder wick or a manual de-solder pump. Using a vacuum unit is more comfortable, of course but not strictly necessary.
Soldering the new parts requires no special tools, a normally sized (~30 W) iron is sufficient, a temperature regulated one even better but not a must.
13960
13961
Now everything has to be put back together. In theory the same steps as during disassembly just in reverse order. Connecting the stepper motors is (again) a little fiddly but can be accomplished without special tools.
The most dangerous part is attaching the PCB to the housing by means of the silver-coloured screws. As mentioned before, they are responsible for the electrical connection of the gauges to the PCB.
Their threads are located inside the gauges and are easy to twist-off. Hair-thin wires are attached to them. If a twist-off happens they are very likely to snap.
This can be repaired but is a very delicate task and replacement gauges are expensive. To avoid any of this from happening it's best to follow these rules:
Insert and rotate the screws with your fingers until they are safely engaged.
Use a screwdriver and rotate the screw with two fingertips (not more) until the spring washer just starts to compress.
Tighten the screw further until the washer just reaches full compression, a few degrees more at maximum.
After all this has been accomplished successfully the unit can be installed back into the car.
13962
Check if all lamps light up, backlight is working, RPM and speed values are correct. If no adjustments have been made to the calibration potentiometers the display should still be sufficiently accurate. In any case, ensure that the displayed speed is not below the actual speed as this is illegal in most countries.
<< -- continued below -->>