Table of Contents
Advertisement
No.
Problem
Hsync Distortion
Color Sensitivity,
bar edge distortion
RC: default
NOISE_BS=15
too high
2.1.1.4. Recommended Workarounds for VCT 49xyI-F1
Although the field problems have been fixed successfully, there are recommendations for specific input-signals.
Please consider the following table.
No.
Issue
W1
Imbalance control can cause prob-
lems when changing from high to
low RF signal levels
W2
MOD_ACCU_BS must be written
several times until value is accepted
W3
FM radio not working; root cause:
fast carrier recovery is automatically
ON in FM radio mode, should be
OFF
W4
When switching to FM-Radio mode
the output frequency sometimes will
not be set correctly
W5
Reduction of NICAM sensitivity at
weak RF signal conditions
CIRCUIT DESCRIPTIONS
Countries
Workaround
for C7 / Dx
Malaysia
Speed up DRX video AGC:
- KI_CHANGE_TH=1
- VAGC_REDUC=1
India,
Reduce NOISE_BS to 8
Malaysia
(partly adaptively when
chroma level is small)
Workaround for F1
If TAGC_I = 0:
- set MOD_Ir = 0
- set MOD_If = 0
- write MOD_ACCU_BS = 0
(consider also W2)
Write MOD_ACCU_BS until readback
value matches written value (remember
that MOD_UPDATE has to be 1 for writ-
ing MOD_ACCU_BS)
Set PHAC_PB to 1 in FM radio mode
only, to 0 in TV modes
Repeat switching to FM-Radio mode
and subsequently read out AFC_DEV
until the value is 0
Set PHAC_PB to 1 in NICAM audio
mode
Side-Effect
Status in F1
none
previously
forced val-
ues now
default
Measured
unchanged
Video S/N
(0xF still
1-2dB
default)
smaller
Side-Effect
none
none
none
none
none
Recommen-
dation for F1
remove WA
keep WA
Plan for F2
under inves-
tigation
firmware
redesign
firmware
redesign
firmware
redesign
under inves-
tigation
Advertisement
Table of Contents
