Service manual

Error 2
The HOP (pos. 7301 on diagram B4 detects the absence of an HFB pulse (pin 4 of
connector 0324 on LSP, diagram A3)). A bit will be set in the HOP. After filtering by the
software, the set will switch to protection mode.
Error 3
This protection is activated when the high-tension voltage of the set is too high. It is
called X-ray protection. This protection is triggered by circuitry around 3475 on diagram
A3.
Error 4
When the +5V protection is active, the set is switched to protection and error code 4 is
placed in the error buffer. The LED will blink 4 times (repeatedly).
A 5V failure can cause a drop in the 5V supply output, resulting in an undefined
behavior of the set. Therefore, some I
2
C devices (Tuner and MSP) connected to the
5V supply are constantly monitored. When none of these devices responds to the
microcontroller for a prolonged time, the microcontroller assumes that there is a failure
in the 5V supply.
By starting up (disconnecting/reconnecting the AC power cord) the set via grounding of
the 'FRONT-DETECT' line (on the side I/O), the +5V protection will be overruled, and it
will be easier to determine the cause. The +5V protection will be activated when these I
2
C devices fail (no I
2
C communication): Main Tuner (pos. 1200 on the LSP), MSP3452
sound processor (pos. 7651 on the SSB).
The following tips are useful to isolate the problem area, after overriding the +5V
protection. Determine whether:
The MSP sound processor is loading the +5V; isolate 3650 and/or 4604 (see diagram
B6).
The main Tuner is loading the +5V source; isolate coil 5200.