Sanyo HV-DX4EV Service Manual page 5

TROUBLESHOOTING
2. SYSTEM CIRCUIT
A. LED DISPLAY
No LED display.
NO
Is 5V obtained at IC701
Check R588, D857, L503, L860
pin #9, 25?
YES
NO
Oscillation at IC701pin #1?
YES
Specific GRID/SEG doesn t function.
YES
NO
Check IC 701 pin #22~24, 27,
GRID output at PORT of IC701?
YES
NO
SEG output at PORT of IC701?
Check IC 701 pin #10~12, 14~21.
Exchange IC701.
28, 30, 31.
Exchange IC701.
6
B-1. Bad playback quality (1)
Noise appears on the
playback screen.
NO
Is noise diminished by tracking
Re-adjust PATH.
adjustment.
YES
NO
Noise band is trembled up and
Noise appears on the screen even
down?
though changing tape.
YES
NO
Is there CTL pulse at IC501 Is the height of CTL HEAD normal?
pin#97? No dust?
YES
Is there problem in CTL Input
Check IC501.
circuit and amplifier.
B-2. Bad playback quality (2)
Noise appears on the Full
Recheck step B-1
playback screen.
(Bad playback quallty (1)).
YES
NO
Are there SW, HA SW pulse at
Are SW pulse and HA SW normal?
IC501 pin #16, 18?
YES
NO
Check HEAD AMP connector
ENVE Wave at PT01 pin #4?
and HEAD.
YES
Check VIDEO circuit.
7
TROUBLESHOOTING
YES
Re-adjust PATH.
NO
Re-adjust the height of AC HEAD.
Remove the dust.
YES
Check C510,R545~R547
IC 501 pin #91, 92, 98.
NO
Check IC501.
YES
Check PCB Pattern.