Strong SRT4375 Service Manual page 26

5.2.2. When "NO SIGNAL" message appears
(1) U103:(KA317(Regulator))-> pin 3 : 21V~24V
U103:(KA317(Regulator))-> pin 2 : 13V /18V
If confirm that voltage is measured and is not measured, U103 change
Action) : When U103's(KA317) input voltage is low, do you change SMPS,
(2) Measure by Voltage Meter(Oscilloscope) whether VERTICAL(13Volt) or
HORIZONTAL(18Volt), 22KHz(ON/OFF) is displayed normally measuring
voltage of F100's Lead(or Tuner LNB OUT PORT) when do SCAN
satellite in INSTALL MENU.
(LNB supply voltage check)
(3) When LNB voltage(13V/18V) is not displayed, it changes Q121(TR:kta1273) if
13V/18V is displayed measuring Q121's(TR:kta1273) Emitter monad by
Voltage Meter and measure whether 13V/18V is displayed in F100(Poly
Switch)
Action) : If mania is happened to F100 or Q121 after shift Tuner shift
3. When "Tuner connect Fail" Message happens
If POWER supplied to Tuner is normalcy, Tuner must change.
4. When " FLUSH DRAM " Message happens
U50(L64005) and U51(KM416S1020) Re-soldering do, and
change U50(L64005) if is happened again.
5. Normal Message as being displayed, change MICOM if TV screen
does not come
do U103 Voltage Line check in SMPS if change SMPS and is
low.