HP s7650 CRT monitor – How to enter the service mode, schematic, adjustments

   Exercise care when servicing this chassis with power applied. Many B plus and high voltage terminals are exposed which, if carelessly contacted, can cause serious shock or result in damage to the chassis. Maintain interconnecting ground lead connections between chassis and picture tube dag when operating chassis.
   Certain HV failures can increase X-ray radiation. Monitor should not be operated with HV  levels exceeding the specified rating for the chassis type. The maximum operating HV specified for the chassis used in this monitor is  23.0KV ± 1KV  with a line voltage of 120/240 VAC. Higher voltage may also increase possibility of failure in HV supply.
It is important to maintain specified values of all components in the horizontal and high voltage circuits and anywhere else in the monitor that could cause a rise in high voltage or operating supply voltages. No changes should be made to the original design of the monitor.

   To determine the presence of high voltage, use accurate, high impedance, HV meter connected between second anode lead and CRT dag grounding device. When servicing the High Voltage System, remove static charge from it by connecting a 10K ohm resistor in series with an insulated wire (such as a test probe) between picture tube dag and 2nd anode lead.(AC line cord disconnected from AC power outlet.)

Factory preset Timings Adjustment:
A. Press MENU Key to show OSD window press Up or Down Key to switch the functional controls.
B. Press the Up Key to select the "MORIE" function, then press the SELEC Key. While do not release the SELEC Key until the OSD window changed to the Factory preset window.
C. The Factory preset window contains the following functional controls. Select one of the control. Then press the Up/Down Key to adjust its value for the optimum picture.

D. To switches the input signal to the other Timing Mode. Please follow step A ~ C to get the optimum picture.(H/V-size:312*234mm)

E. Select the "BACK " RETURN function and press the MENU Key, then the Factor Preset window will be returned to the original OSD window.(user's operating condition)
F. The setting data of the CONTRAST, BRIGHTNESS, ROTATION, and COLOR TEMPERATURE are common mode saved in the memory. Don't needed adjust it individual at every timing Mode and save in the memory.

Micro Controller Circuit
The IC101 contains a 6502/8051 8-bit CPU core, 512 bytes of RAM, 16K bytes of ROM,14 channel 8 bit PWM D/A converters, 2 channel A/D converters for key detection, one 8 bit pre-loadable base timer, internal H-sync and V-sync signals processor providing mode detection, watch- dog timer preventing system from abnormal operation, and an I²C bus interface.

Circuit diagram: PWB

15-Pin Display cable

H/V sync signals processor
The functions of the sync processor include polarity detection, H-SYNC & V-SYNC signals counting, Programmable SYNC signals output, free running signal generator. Pin39/Pin40 are for the H-SYNC and VSYNC input, Pin32/Pin33 will output the same signal as input sync signal without delay, and the polarity are setting in the positive. When no signal input, the Pin32 will output a 72Hz V-SYNC free run signal. The Pin33 will output a 48KHz H-SYNC free run signal. for the monitor testing use.

Deflection Circuit

The deflection circuit is achieved by a high performance and efficient solution IC 401 (STV9118) for this monitor. The concept is fully DC controllable and can be used in applications with a micro-controller solutions. The STV9118 provides sync. Processing with full auto sync. Capability, a flexible SMPS block and an extensive set of geometry control facilities. Further the IC generates the drive waveforms for DC coupled vertical boosters to the STV9302A.
Horizontal Oscillator
The oscillator is of the relaxation type and requires a capacitor of C409 at pin6. The free running frequency is determined by a resistor R412 from pin8 to ground.
PLL 1 Phase Detector
The phase detector is a standard one using switched current sources. It compares the middle of H-sync. With a fixed point on the oscillator saw-tooth voltage. The PLL loop filter C435, C437, R411 is connected to Pin9.
PLL2 Phase Detector
This phase detector is similar to the PLL1 detector and compares the line flyback pulse at pin 12 with the oscillator saw-tooth voltage. The PLL2 detector thus compensates for the delay in the external H-deflection circuit by adjusting the phase of the HDRV output pulses. The phase between H-flyback and H-sync can be controlled at pin5.

X-ray Protection
The X-ray protection input pin25 provides a voltage detector with a precise threshold. If the voltage exceeds this threshold for a certain time, an internal latch switches the whole IC into protection mode. In this mode several pins are forced into defined states:

Pin28 (BDRV) is floating
Pin26 (HDRV) is floating
Vertical Oscillator
The vertical free –running frequency is determined by the capacitance C613 at pin22. Usually the free-running frequency should be lower than the minimum trigger frequency