akira PTV-50H08 User manual

Projection TV
Service Manual

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Model No.: PTV-50H08
Version: 1.0
MODEL:
PTV-50H08

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Model No.: PTV-50H08
Version: 1.0
CONTENTS
SAFE NOTICE......................................................................................................................................... 4
SPECIFICATION ..................................................................................................................................... 7
TV SET OVERVIEW............................................................................................................................... 8
MAINTENANCE ADJUSTEMENT ....................................................................................................... 9
NOTICE FOR MAINTENANCE .......................................................................................................... 21
CIRCUIT DIAGRAM ............................................................................................................................ 35

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Model No.: PTV-50H08
Version: 1.0
SAFETY NOTICE
Use an insolating transformer during maintenance.
In this manual and the parts list of its annexed tables as well as the schematic circuit diagram, those
components with special safety functions are marked with “ ! ” need paying special attention upon
maintenance. Maintainers shall carefully read the “Safety Notices” and “Safety Precautions” in the
manual before maintaining the TV set core.
Important: In case the projection tube is replaced, only the same model or an equivalent model certified
by “CB” shall be used to ensure the protection function to the X-ray.
The maintenance of this product is only applicable to the qualified maintenance technicians, which
means that unauthorized maintenances are forbidden. The qualified technicians shall have necessary test
equipment and special tools, and shall have been trained with those complicated products said in this
manual to have the ability to maintain safely such complicated products as the projection TV set said in
this manual.
Improper maintenance may affect the safety and reliability of the product. If you are not qualified to
maintain the product, never take a risk trying to maintain it, find a qualified maintainer to maintain it
instead.
W a r n i n g
When maintain or handles the circuit plank to imply with the other a piece that soldering lead feet,
should avoid the soldering getting in touch with skin directly. At the same time, notice and do not
inhale welding a creation any smoke or airs.
Safety Precautions
1 Check and test the complete TV set maintained for safety before handing it to the costumer. The
items to be checked and tested are as follows:
a. Make sure that the safeguard devices and parts are in good condition, and not removed during
the maintenance.
i. The safeguard devices and parts of this TV set core for protecting the technicians and
costumers shall be all reinstalled properly, including those removed for maintenance
convenience.
ii. Always operate the TV set with all the safeguard devices and parts reinstalled properly
after the reassembly of the TV set core and other assemblies.
iii. Any maintenance negligent of the safety precautions or without safety check and test
may cause dangers.

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Model No.: PTV-50H08
Version: 1.0
b. Make sure there are no gaps with the shell so as to prevent adults and children from putting
fingers inside and touching the dangerous voltage. The gaps include but not limited in:
i. Gaps with the front frame are too large.
ii. The back cover is not installed properly or correctly.
c. Test of antenna cold junction: Connect the two pins of the TV set plug with a piece of
conductor, with the TV set switched on. Connect one end of the ohmmeter to the pin of the plug,
and the other end to the antenna input terminal of the tuner or the bare screw. Connect to the
coaxial cable if possible. If the resistance is less than 8 ohms or greater than 11 ohms,
abnormalities must exist, which shall be removed before the TV set is submitted to the
costumer. Repeat the above test with the TV set switched off.
d. Leakage current test: After the reassembly, insert the mains plug of the TV set into a 40Vsocket
(Do not use an insolating transformer during the test. The test connection is shown in Fig.1.).
Test with a leakage current meter or test system first with the switch on, then with the switch
off. Test the leakage current of the known groundings (metal pipes) to each of the bare metal
parts (the antenna, the knob supports, the metal front frames, the screw ends, the metal covers,
the control buttons, etc.) of the TV set, especially the bare metal parts connected to the core.
None of the currents shall be more than 0.7mA. Repeat the same tests with the polarity of the
plug exchanged. Any leakage current values beyond the limits may cause electric shocks, which
shall be tackled before returning the TV set to the costumer or connecting antenna or
accessories to it.
e. A high voltage limiting circuit (HVLC)is equipped with the TV set to control the high voltage
under the set value. Upon maintenance, do as specified in all the notes of the maintenance
manual, and the HVLC will function properly.
f. Maintenance warnings: At the largest contrast ratio, the high voltage of the TV set is lower than
31.0kV. In case parts affecting the high voltage are replaced, verify whether the high voltage of
the TV set is lower than 31.0kV at the largest contrast ratio. Use a voltage meter with a large
resistance and anti high voltage, to measure the high voltage. Connect the negative pole to the
grounding of the TV set core, and the positive pole to the high voltage connector. the connection
of the high voltage meter is shown in Fig. 2.
Note: Always turn off the powers of the TV set and the high voltage meter before connecting the positive
pole.
g. The X-rays (projection tube): The X-rays generated by the TV set are mainly from the
projection tube. Therefore the TV set takes use of the above said functions to reduce the
radiation hazard of the X-rays. In case the projection tube is replaced, only the same model or an
equivalent model certified by “CB” shall be used to ensure the protection function to the X-ray.
While troubleshooting or testing the TV set, avoid getting close to the projection tube and the
high voltage parts. Never run the TV set core for a very long time when troubleshooting the
causes of over high voltage.

Fig.1 Fig.2
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Model No.: PTV-50H08
Version: 1.0
2 Carefully read and follow the warnings and safety precautions on the receiver shell, the core and the
projection tube.
3 Warnings on design modification: Never modify or supplement the mechanical or circuit design of
the TV set. Circuit modification and suc h supplement as the assistant audio/video output adapter
may alter the safety performance of the TV set and injure the users.
4 Warnings on anti-explosion of the projection tube: the projection tube of the TV set uses a complete
explosion protection design; use the same model of projection tube upon replacement. Always wear
a pair of goggles when moving, installing or handling the projection tube. While handling the
projection tube, keep persons without goggles away from it. Put the projection tube at a place away
from people. Never handle the projection tube by the tube neck.
5 Warnings on the hot core: usually maintain a hot core with an isolating transformer connected to
assure safety. The energized end of the mains circuit of a cold core is connected to the AC mains,
therefore maintenance shall also be made with an isolating transformer connected for better safety.
6 Pay attention to the original lead covers, especially those in the following areas, to assure proper lead
covers:
a. The area near to sharp edges.
b. The area near to hot parts. Make sure that the leads do not touch the hot parts.
c. The AC mains.
d. The high voltage.
e. The antenna cable.
Check all the areas for the pressed, pulled or injured cables; don not alter the space between every
two components and printed circuits; check the AC mains cable for damage.
7 Replace over heated or damaged components, parts or cables with new ones of the original
specifications. In addition, find the causes to be over heated or damaged, and if necessary, take
proper measures to eliminate any hidden dangers.
8 Safety precautions to the parts: many electronic and mechanical parts of the TV set have special
safety functions, some of which cannot be observed from their appearances. Although other parts
with high voltages or greater power can be used instead, the safety performances of those parts still
cannot be assured. The components marked with “ ! ” have special safety functions. Always Replace
these parts with those recommended in the replacement part list to avoid such dangers as electric
shocks and fires.

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Model No.: PTV-50H08
Version: 1.0
SPECIFICATION
Screen size 50”
Projection tube 7” (P16LXL00 / P16LSG03)
Lens D250 (R/G/B)
Anode high voltage 30.2kV
Mains voltage 175 – 250VAC; 50/60Hz
Power consumption 250W
Receiving system PAL D/K, B/G, I; SECAM D/K, B/G, L/L
Frequency ranges E2 – E9, S10 – S41, S38 – DS57
Antenna input 75 Ωimbalanced input
Number of channels 200
Audio output 12WX2
Comb filter 3D digital comb filter; PAL/NTSC system
Digital convergence Yes
NICAM receiving Yes
Teletext Yes
BBE Yes
SRS Yes
S-VIDEO input terminals One side set and one back set
Video input terminals One side set and two back sets
Chromatic deviation input
(YprPb/YcrCb)
One back set
Audio (L/R) input terminal One site set and two back sets
Earphone output jack One on side
Video output terminal One back set
Weight 62kg
Dimension W x H x D 1260mm x 1480mm x 745mm
Screen shielding Yes
Protector
Protector Specification Circuit protected Chassis with the protector
F908 RT1-20-4A AC mains circuit Secondary mains board
FP01 RT1-20-3. 15A Primary mains circuit Mains deflexion board
F902 RT1-20-3. 15A Secondary mains circuit Secondary mains board

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Model No.: PTV-50H08
Version: 1.0
TV SET OVERVIEW

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Model No.: PTV-50H08
Version: 1.0
MAINTENANCE ADJUSTMENT
Adjustment Methods
1 How to enter the “M” status: with the MENU key pressed, press keys MUTE and TXT on the
remote controller successively
How to leave the “M” status: press the channel plus key on the front panel.
2 How to enter the aging status: At the “M” status, press Key Recall on the remote controller to enter
the aging status; now the “M” sign shows red.
How to leave the aging status: press Key Recall on the remote controller for more than two seconds
to leave the aging status; now the “M” sign shows green again.
3 How to enter the status of a bright line: At the “M” status, press Key Still on the remote controller to
enter the status of a bright line, and press Key Still on the remote controller once more to leave the
status of a bright line.
4 How to enter the status of geometry linearity adjustment: In the TV mode, with Key SK01 pressed,
press Key MUTE on the remote controller to enter the status of geometry linearity adjustment; press
Key SK01 to leave the status of geometry linearity adjustment.
5 How to enter the status of under convergence adjustment: Turn on the TV set with Key SK01
pressed to enter the status of under convergence adjustment, now the three-color squares displayed
on the screen. Press SK01 or Key CONV on the side panel to exit.
6 How to enter the status of convergence adjustment:
Method One: In the TV mode, press SK01 to enter the status of convergence adjustment.
Method Two: In the TV mode, press Key CONV on the side panel together with Key TV/AV on the
remote controller to enter the status of convergence adjustment.
Press Key SK01 or CONV to exit.
7 How to select the color in the status of convergence adjustment: In the status of convergence
adjustment, press Key picture on the remote controller to switch between colors. The switching
order is: Single green (adjust the green), red + green (adjust the red) and red + blue + green (adjust
the blue); press Key Audio to select the display color.
8 How to select the mode of convergence adjustment: In the status of convergence adjustment, press
Key TXT on the remote controller to select between Modes 13X16 and 5X5.
9 How to move the cursor during the convergence adjustment: Press digital Keys 2 , 4 , 5 , 6 and 8 ,
and the cursor moves as follows:
Digital Key 2-------- cursor up
Digital Key 8--------cursor down
Digital Key 4--------cursor left
Digital Key 6--------cursor right
Digital Key 5--------cursor back to the original center

3
2
5
4
4
4
5
1
1.Central Magnetic Sheet of Red Tube 2. Central Magnetic Sheet of Green Tube
3.Central Magnetic Sheet of Blue Tube 4. Four Magnetic Sheets for Beam Shape Adjustment
5. Magnetic Sheet for Beam Alignment Adjustment 6. Focusing Case Assembly
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Model No.: PTV-50H08
Version: 1.0
10 Data adjustment is the status of convergence adjustment:
Remote controller: Key Channel Plus -------- Data increasing (up)
Key Channel Minus -------- Data reducing (down)
Key Sound Plus >--------- Data increasing (right)
Key sound Minus <---------Data Reducing left
11 Switch between the fine adjustment and the coarse adjustment: In the status of convergence
adjustment, press Key i on the remote controller to switch between the fine adjustment and the
coarse adjustment, with the default mode being the coarse adjustment, and with additional line
adjustment function in the 13X16 mode.
12 How to write the data of convergence adjustment: In the status of convergence adjustment, press
Key Write and confirm the action (press Key Sound to confirm, and Key Mix to quit) to write the
data of the current system into the E2PROM, which will not be lost after power off.
13 How to read the data of convergence adjustment: In the status of convergence adjustment, press Key
Read and confirm the action (press Key Sound to confirm, and Key Mix to quit) to read out the data
of the current system.
14 How to clear the data of convergence adjustment: In the status of convergence adjustment, press Key
Reset and confirm the action (press Key Sound to confirm, and Key Mix to quit) to clear the current
system and the convergence data.
15 Diagram of Adjustment Spots
a. Projection Tube