Table of Contents
Advertisement
www.freeservicemanuals.info
Service modes, fault finding and repair tips
5.6.4
Vs and Va protection
Va protection
When this protection is activated, the Va- and Vs power supply
are shut down. The set is switched to the standby mode and
error-code 4 is stored in the NVM.
When the Va-supply exceeds the 68V, regulator 7112 is
triggered and will switch on T7113. Capacitor 2132 is charged
via the 5Vstby-switched and will trigger thyristor 7114, which
will switch on T7341. The voltage dividing of R3386 and
resistor R3378 and 3379 now determine the voltage "protection
status". ( neglect the Vce of 0.2V of T7341 ). See schematic
FD2.
The presence of the voltage at "protection status" line will
eventually reset the VsVa-supply. For more info see
subparagraph - Reset of the VsVa-supply.
Vs protection
When this protection is activated, the Vs power supply is shut
down. The set is switched to the standby mode and error-code
4 is stored in the NVM.
When the Vs supply exceeds the 198V, regulator 7012 is
triggered and will switch on T7016. Capacitor 2032 is charged
via the 5Vstby-switched and will trigger thyristor 7013. Thyristor
7013 is fired and connects signal Aa to ground. To follow the
signal flow, go to the right upper corner of schematic FD1.
When signal Aa is shorted to ground, T7341 is switched on.
The voltage dividing of R3386 and resistor R3378 and 3379
now determine the voltage "protection status". ( neglect the
Vce of 0.2V of T7341 ). See schematic FD2.
The presence of the voltage at "protection status" line will
eventually reset the VsVa-supply. For more info see
subparagraph - Reset of the VsVa-supply.
5.6.5
Temperature Protection
When this protection is activated, the Va- and Vs power supply
are shut down. The set is switched to the standby mode and
error-code 5 is stored in the NVM.
When the temperature of the heatsink on the Preconditioner
panel or on one of the 2 heatsink on the VsVa panel exceeds
the 110°C, the PTC resistance increases drastically. The
voltage at pin 3 of IC7330 will drop and the output of 7330 will
do the same. The current flow through opto-coupler diode 7331
results also in a current flow through the opto-coupler transistor
and will trigger thyristor 7332. The fired thyristor switches
transistor 7337 on. The voltage dividing of R3339 and resistor
R3378 and 3379 now determine the voltage "protection status".
( neglect the Vce of 0.2V of T7337 ).
The presence of the voltage at "protection status" line will
eventually reset the VsVa-supply. For more info see
subparagraph - Reset of the VsVa-supply.
5.6.6
DC Protection - Audio Amplifier
When this protection is activated, the Va- and Vs power supply
are shut down. The set is switched to the standby mode and
error-code 6 is stored in the NVM.
In case of a fault in the Audio amplifier or when a DC voltage
appears on the speaker output, a signal called DCPROT is
generated. See schematic FD2 - F7. In case of a fault,
thyristor 7314 is triggered and switches on T7340. The voltage
dividing of R3380 and resistor R3378 and 3379 now determine
the voltage "protection status". ( neglect the Vce of 0.2V of
T7340 ).
The presence of the voltage at "protection status" line will
eventually reset the VsVa-supply. For more info see
subparagraph - Reset of the VsVa-supply.
3/2/2013
5.6.7
Vrr - PDP supplies
Vrr is a logical signal ( "high" in normal circumstances ) that
comes from the PDP. It's purpose is to trigger the switch-off of
the Pre-conditioner supply in case Vrr becomes "low" , to
trigger the shutdown of the VsVa supply and to initialise that
error-code 7 is stored in the NVM.
When signal Vrr becomes "low", see FD1 - section F13, the
output of IC7301-B becomes "high". This results in two actions.
It will trigger thyristor 7302 and short signal PROTS to ground.
This results eventually in a reset of the VsVa supply.
Switching on T7371, which again switches on T7370 via the
5Vstby-switched supply. Signal-line "supply-on" is now
grounded. This results in switching off relay 5680 and 5690,
disconnecting the mains from the pre-conditioner. The standby
supply ( 5Vstby-switched ) is still functional. (See Fig. 5-5)
5.7
Fault finding tips
5.7.1
Pre-conditioner
The Pre-conditioner delivers the following output voltages:
•
•
•
•
To trouble shoot the pre-conditioner, first check the LED of the
display-box.
•
Check the +5Vstby_switched on pin 5 of connector PR08. If
this voltage is present check the presence of this voltage at the
VsVa-panel on pin 2 of connector FD04. See the wiring
diagram of the monitor for more details.
If the voltage is not present, check R3508 and fuse 1500. In
case of a defective R3508, check/replace item 7500, opto-
coupler 7501, regulator 7502, and diode 6501 + 6502.
In case of an open circuit of fuse 1500, check/replace bridge
6500 and capacitor C2501.
If both component are alive, measure the voltage at pin 5 of
IC7500 - Topswitch. If the waveforms resemble a burst-signal,
the output is too heavy loaded. Check the output diode D6504
and capacitor C2508 of the 12VSB and diode 6505 and
capacitor C2510 of the 5VSTBY.
•
Disconnect the VGA-cable between the E-box and the Monitor.
Now the Monitor is operating as a stand-alone unit.
Switch the monitor via the DST, (command "Default") or via the
RC (special sequence) to the SDM.
Automatically the orange coloured LED of the monitor will blink
the content of the error-buffer. If the sequence contains error-
code 8, the cause could be a defective pre-conditioner. Error-
code 8 is an indication that the +5V and/or the Vs/Va of the
VsVa supply are not correct.
In case of error-code 4, switch OFF the set and check the
temperature of the heatsink. In case of a high temperature of
the heatsink, check MOSFET T7610 and the drive-circuit
around T7640, T7641 and T7608.
In case of error-code 8, remove connector PR09 from the
board. Short-circuit pin 2 of T7681 to ground, simulation of
"SUPPLY_ON". (Caution - Protections overruled!!!)
Measure voltage at C2616. Is voltage 380Vdc?
Yes, the cause was a too heavy load/short-circuit at the VsVa-
panel.
No, measure the voltage at C2606/C2607. Is this voltage a DC-
voltage of approx. 300V with a strong ripple at a mains-input of
230Vac? If NO, check if relay 5690 is activated via the
transistors T7684 + T7690. Check also PTC's 3600, 3601 and
3602 at their resistor-value.
World of free manuals
FTV1.9DE
5 VSTBY
5 VSTBY_switched
380 VDC
Internal 12 VSTBY to supply the relay, which switches the
mains input
No red, green or orange LED indicates the absence of the
+5Vstby_switched at the VsVa panel.
The red LED is blinking (+5Vstby is OK!), which is an
indication of a protection.
www.nostatatech.nl
5.
GB 15
Advertisement
Table of Contents
