CCU Computer board Service - Part 1/3

[Kaz-kzukNA1]

Recently, I was helping another owner for his Air Con (A/C) CCU.

The owner visited my place to take Health Check Service on his NSX and although he didn’t notice any issues with his A/C, he wanted to have his CCU serviced as a preventative measure considering the age of his NSX. It was a 96 model.

So, during the Health Check Service, I removed the CCU for the owner and while I was removing it, the owner watched the whole procedure so that he can re-install it by himself.

After the removal of CCU, I opened the box and showed the state of the board in front of the owner.


Straight away, we noticed that someone already worked on the board in the past with very poor soldering technique. Also, just one capacitor was replaced and rest of them were left without being touched. As the result, there were several leakage from old capacitors causing further issues.
In fact, while I was showing the board to the owner, the jumper wire that someone used in the past came off so it was good to have it serviced any way.


After this, I inspected the board further and found that one of the track at diode array DM11 was not even repaired and causing almost open circuit.

For CCU service, replacing the capacitors are very small part of the actual process. Only 13 capacitors to be replaced so won’t take too long.


Most of the time is being spent on the test process as well as cleaning and repairing of damaged circuit tracks and pads. For this board, I had to use three jumper wires and one hard wire plus soldering bridge to re-create the GND plain at C44.

After the standard check process, the board was coated and then final test and diagnosis check were carried out.

The serviced CCU board was returned to the owner by Royal Mail Special Delivery Next day service with maximum insurance value of GBP2,500.

After this, I had a phone call from the owner stating that he was experiencing some issues with his A/C. He mentioned that even he changed the temperature setup, the air mix motor (water valve) didn’t move and thus, no changes in the air temperature.
I explained the test procedures at the final stage of my service based on the check sheet which included the visual inspection of water valve using my NSX so asked him to re-check all connections and offered several options to solve this issue.

After a short waiting time, I had another phone call from the owner and he found that he didn’t connect the big green connector at the back of the CCU properly and it got loose.
After it was fully connected, everything worked fine and the owner was happy.

Another CCU saved.
Hope you will also consider having your CCU serviced before it’s too late….


Regards,
Kaz