Sylvania 6620LE Service Manual page 37

Main CBA Top View
CAUTION !
Fixed voltage (or Auto voltage selectable) power supply circuit is used in this unit.
If Main Fuse (F601) is blown, check to see that all components in the power supply circuit
are not defective before you connect the AC plug to the AC power supply.
Otherwise it may cause some components in the power supply circuit to fail.
TP300
GND
TP401
+21V
VR649
+21V
CAUTION: FOR CONTINUED PROTECTION AGAINST RISK OF
FIRE, REPLACE ONLY WITH SAME TYPE 4A, 125V FUSE.
ATTENTION: UTILISER UN FUSIBLE DE RECHANGE DE MÊME
4A/125V
TYPE DE 4A, 125V.
NOTE :
The voltage for parts in hot circuit is measured
using hot GND as a common terminal.
WF9
WF8
PIN 19 OF PIN 21 OF
CN103A CN103A
8-13
BECAUSE A HOT CHASSIS GROUND IS PRESENT IN THE POWER
SUPPLY CIRCUIT, AN ISOLATION TRANSFORMER MUST BE USED.
ALSO, IN ORDER TO HAVE THE ABILITY TO INCREASE THE INPUT
SLOWLY, WHEN TROUBLESHOOTING THIS TYPE POWER SUPPLY
CIRCUIT, A VARIABLE ISOLATION TRANSFORMER IS REQUIRED.
WF7
PIN 23 OF
CN103A
WF6
PIN 14 OF
IC801
BL0300F01013-1