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+5/12 Volt Regulator
Loss of voltage due to shorts or device failures on either +12 or +5 volt output lines can occur. Consequently, IC605
or IC608 can be damaged and need replacing. Before replacing either IC, check for shorts or damaged parts along the
output lines. If +12 volt does not appear, check the remote on/off signal from IC901 pin 6.
Standby 5V Circuit
Failure of this circuit can be affected by IC607. In case the circuit does not work properly, check D605, D614, R634,
R611 and Q604. If these components are good, check the remaining circuit parts.
Heater Voltage Regulator
This circuit may be affected by fusible resistor R634 or D619. If these parts are good, check the regulator output for a
short to ground. Shorts can occur on the video board. In the case of an output short, IC602 may have been damaged.
If the IC appears to have no damage, check for any problems with the heater on/off signal.
Feedback Circuit
Problems with feed back can cause power supply shut down or low voltages. First determine whether the power
supply is operating in active off, active on modes or not at all.
The power supply can be stuck in active off mode. The remote on/off signal, Q603, Q604, D605 and IC603 can affect
this condition. Likewise, if the power supply is always in active on mode, the same items should be checked.
Checking for voltages at IC603 pins 1 and 2, IC604 pins 1 and 3 can solve more difficult problems. Additionally,
IC603 pins 4 and 5, and IC601 pin 9 should be checked. If there are problems with these devices, 180V or standby
5V line, the feedback systems will not work correctly. Also check the protection circuits.
Protection Circuits
OCP occurs when there is excessive current through Q602. Failures with Q510, Q507 or the video section could
cause this condition. These areas should be checked. OCP condition can also occur if R614 or R654 are open; if
R623 is shorted; or if R624 is open.
OVP usually occurs when the feedback loop is open, or loss of standby 5V. Isolate the OVP trigger condition, by first
checking the operation of the feedback loop.
D BOARD DEFLECTION SECTION
1. Horizontal Deflection Circuit
Overview
These circuit drive the DY (Deflection Yoke) for Horizontal Deflection. The H size and H shape control (IC501 and
around) is included in this page as well.
H Drive, H Out, Feedback
+12Vp-p HD pulse is generated by the inverter Q903 using the Jungle IC902 H. out pin #17. And switch Q511
through A push-pull amplifier (Q501 and Q502) buffers. The drive current which introduced in HDT (T504) by this
switching will drive Q507 (H out Tr) and 1000V pulse appears on collector. D506 is the "Damper Diode" which avoid
the negative pulse and discharge the energy for next Horizontal Drive. Q508 is the buffer for the "H BLK" feed back
to Jungle IC 902 H. FLY pin #14 and it will be the reference of phase / jitter control of Jungle. HST (T505) is to sense
the deflection current through DY. The voltage appeared on secondary side will be the feed back for H Size/Shape
control.
H Size/Shape control
HD pulse also triggering the H Size/Shape control IC501 pin #8. IC501 is "PWM IC" and it controls H and HV B+
chopper duty. H Shape and H size information is already included and coming from Jungle IC902 E/W pin #9. It will
be supplied to IC501 pin #2. H reg output pin #20 is switching pulse of Q520 (B+ chopper). The energy supplement
from 180V to H Def circuit (through L503 HOT) is controlled by the duty of this pulse. The H Shape input and
feedback voltage from T505 are compared by error amp (in IC501) and H Reg out pulse duty is controlled to keep the
level of these two the same.
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Troubleshooting
