Results 1 to 4 of 4

Thread: Gauge Cluster Capacitor Replacement

  1. #1
    Join Date
    Jan 2018
    Location
    Near Stuttgart, Germany
    Posts
    246
    Blog Entries
    25

    Lightbulb Gauge Cluster Capacitor Replacement

    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) 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) 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.

    Click image for larger version. 

Name:	IMAG3555s.jpg 
Views:	514 
Size:	97.7 KB 
ID:	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.

    Click image for larger version. 

Name:	IMAG3556s.jpg 
Views:	407 
Size:	140.3 KB 
ID:	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.

    Click image for larger version. 

Name:	IMAG3557ss.jpg 
Views:	1992 
Size:	241.7 KB 
ID:	13972

    As mentioned in the entry about the 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.

    Click image for larger version. 

Name:	IMAG4004s.jpg 
Views:	1672 
Size:	149.4 KB 
ID:	13960

    Click image for larger version. 

Name:	IMAG4005~2sf.jpg 
Views:	1670 
Size:	143.1 KB 
ID:	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.

    Click image for larger version. 

Name:	IMAG4008s.jpg 
Views:	1625 
Size:	117.3 KB 
ID:	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 -->>
    Last edited by Heineken; 07-01-2022 at 07:54 AM. Reason: updated information
    1997 JDM Custom Order AT VIN 1400005 - Stock
    Heineken's Garage

  2. #2
    Join Date
    Jan 2018
    Location
    Near Stuttgart, Germany
    Posts
    246
    Blog Entries
    25

    Default

    As I spent much time to create a gauge cluster calibrator I would like to explain the calibration procedure here.

    The tester can drive the two main gauges (RPM and speed) with proper signals as well as provide reference resistance for the temperature, oil, fuel and voltage gauge. Even though the signals are mostly the same, pin numbers changed in 1995 creating two pin-outs: 1990-1994 and 1995-2005. Compatibility with all build years is given, except the temperature gauge >2001.

    To be able to move the needles, we need to supply voltage and ground for each side of the PCB. The left socket drives the RPM, temperature and oil gauge, the right one speed, fuel and voltage.

    Left socket (A) - RPM
    Name PIN (1990-1994)
    Pin (1995-2005)
    12 V A3 A13
    Ground A2 A27
    RPM A4 A28
    Temperature A17 A12
    Oil Pressure A1 A14

    Click image for larger version. 

Name:	NSX Tester - Screenshot_3.jpg 
Views:	1626 
Size:	100.8 KB 
ID:	13968

    Right Socket (B) - Speed
    Name Pin (1990-1994) Pin (1995-2005)
    12 V B9 B2
    Ground B8 B7
    Speed B24 B22
    Fuel B10 B1

    Click image for larger version. 

Name:	NSX Tester - Screenshot_4.jpg 
Views:	1622 
Size:	94.4 KB 
ID:	13969Click image for larger version. 

Name:	NSX Tester - Screenshot_5.jpg 
Views:	1565 
Size:	84.9 KB 
ID:	13970

    Pin numbers can be identified by looking into the socket counting from left to right, top to bottom. The top row is 14-1, the bottom row 30-15.
    Note that the brake light warning and SRS warning lamp light up when power is correctly supplied to both PCBs sockets (due to missing input signals).

    Calibration starts by selecting the highest RPM (8000) first at the tester and working with the left two variable resistors. The right one of the two is controlling the upper range and is now used to put the needle to exactly 8000 RPM. Next we jump to 1000 RPM to calibrate the lower end. Now the intermediate values are checked and if the 8000 RPM is still correct. If not, recalibrate the value 8000 then check 1000 again (and adjust if necessary).
    On every cycle the deviations should become smaller until all values are correct. It shouldn't take more than a few rounds.

    The speed gauge is calibrated in the same fashion, utilizing the other two variable resistors. Be reminded again that it may never show a too low value as this is against the law in most countries.



    The text became much longer than expected but hopefully helpful to those interrested
    1997 JDM Custom Order AT VIN 1400005 - Stock
    Heineken's Garage

  3. #3

    Default

    Well done and thanks again Heineken...supporting the NSX owners with useful knowledge. Top marks

    SS
    Lexus LC500h.......New Daily run around with some saving the Planet thoughts
    Black/black 95 NSX NA with mk1 Ary exhaust....Now sold
    Red/Black 91 NSX treasure.....FI No more NA
    Silver/Pearl White/Black 1993 NSX 3.0 5 MT NSX ZAZ R-GT Twin Scroll Turbo

  4. #4
    Join Date
    Jan 2018
    Location
    Near Stuttgart, Germany
    Posts
    246
    Blog Entries
    25

    Default

    You're welcome
    Last edited by Heineken; 27-10-2020 at 08:25 PM.
    1997 JDM Custom Order AT VIN 1400005 - Stock
    Heineken's Garage

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •