Heineken's Garage

Diagnostic - CPU Issues
A CCU with a non-working CPU won't show any signs of life. All display elements, LEDs, buttons and knobs are non-working. When plugged into the vehicle, no initialization motor movements can be recognized. One way to confirm a CPU problem is to check pin 30 of the CPU with an oscilloscope. That pin carries the clock signal and should show a 11.9 MHz wave of 3 V peak-to-peak:

If the CPU is unable to start, the following ...

.. continuation of Radio Head Unit - Repair III

No display - otherwise fully functional
Observed on: 1 USDM Radio
Fixed by: PCB repair, parts replacement
State: Fully understood

A fully working radio with a non-working display. The display was confirmed OK by installing it into a working JDM radio. An investigation showed heavy leakage by capacitor E818:

IC 802 is providing 9 V to the VFD heater circuit ...

.. continuation of Radio Head Unit - Repair II

CD port not working (e. g. channel loss)
Observed on: 2 EUDM Radio
Fixed by: PCB repair, replacement of OP amp (with adapter PCB, if required)
State: Fully understood

Acid damage to the traces around the CD port OP amplifier can cause the connection to the CD changer to fail.

severe trace damage around the CD port OP amp mounting point

The CD ...

.. continuation of Radio - Repair

Too little Volume and Distortions increasing with Volume
Observed on: 1 EUDM Radio
Fixed by: OP amp replacement
State: Fully understood

The audio signal path on these radios is fully analogue with several operational amplifiers at various stages. One of them is IC303, a 20 V, 10 MHz quad operational amplifier from JRC/NJM: NJM2060M.

IC303 at the rear end of the lower PCB

...

Introduction
Issues with the radio head unit is a common fault, affecting nearly all NSX depending on age and climate zone. Capacitor replacement should be the first step to perform, followed by further analysis and repair.

Diagnostic
The following error cases and ways of repairing have been identified so far. Almost all of them are caused by capacitor leakage but not exclusively since the radios suffer from normal wear and tear similar to other consumer audio electronics. ...