Philips HTD3500 Service Manual page 21

VFD No display on Front Control Board
VFD No display on
Front Control Board
Go
Check every supply voltage on Main Board
whether normal or not.
(XP1 PIN3:+12V, PIN5&PIN6: 5V)
Yes
Check voltage,+5V, +12V on Power Board
at CN502 position and Front Control Board
(HTS3538:XP12 PIN3:+12V PIN5:+5V
Yes
Check the power key(HTS3538: S608),
open/closed key(HTS3538: S611), source
key(HTS3538: S610) on Touch Board
whether work normally or not
Yes
Check Front
SCL,SDA
(HTS3538:XP12PIN6: SCL PIN7:SDA)
Yes
Check whether bad solder exists on
HTS3538:XP3 on Front Control Board and
Yes
Replace U301 or LED
Control Board signals
LED
5-1
No
Refer to CN502 on Power Board
No
Fix the connection HTS3538:XP3 on
Front Control Board
Main Board
No
Replace U1 on Main Board, or replace
the Main Board
No
HTS3538:Check the U301 ON Front
Control Board pin 4 5 arrive the condition
XP3 PIN10 PIN10
No
Correct connection
Trouble shooting Chart
and XP12 on