REPAIRING AND NOT THROWING AWAY

Richtige Fernseher haben Röhren!

Richtige Fernseher haben Röhren!

In Brief: On this site you will find pictures and technical information about Service Modes, Circuit Diagrams, Firmware Update procedure, Disassemble procedure, Universal remote control set-up codes, Troubleshooting and more....

If you go into the profession, you will obtain or have access to a variety of tech tips databases HERE IT IS Master Electronics Repair !.

These are an excellent investment where the saying: 'time-is-money' rules. However, to learn, you need to develop a general troubleshooting approach - a logical, methodical, method of narrowing down the problem. A tech tip database might suggest: 'Replace C536' for a particular symptom. This is good advice for a specific problem on one model. However, what you really want to understand is why C536 was the cause and how to pinpoint the culprit in general even if you don't have a service manual or schematic and your tech tip database doesn't have an entry for your sick TV or VCR.

While schematics are nice, you won't always have them or be able to justify the purchase for a one-of repair. Therefore, in many cases, some reverse engineering will be necessary. The time will be well spent since even if you don't see another instance of the same model in your entire lifetime, you will have learned something in the process that can be applied to other equipment problems.
As always, when you get stuck, checking out a tech-tips database may quickly identify your problem and solution.In that case, you can greatly simplify your troubleshooting or at least confirm a diagnosis before ordering parts.

Happy repairing!
Today, the West is headed for the abyss. For the ultimate fate of our disposable society is for that society itself to be disposed of. And this will happen sooner, rather than later.

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Monday, 22 March 2021

REPAIRING / SERVICING TV AKAI LEA-32V24P

Technical description and composition of the AKAI LEA-32V24P TV, type of panel and modules used. Module composition.

AKAI LED
Model: LEA-32V24P

Chassis/Version: TP.VST59S.P89

Panel: T315XW04 V3 // ST315A04-5

LED backlight: HL-17320A28-0801S-01

LED driver (backlight): integrated into MainBoard

PWM LED driver: OB3350CP

MOSFET LED driver: TO-252

Power Supply (PSU): integrated into MainBoard

PWM Power: LD7536 (PWM SOT23-6 )

MOSFET Power: MDF7N60B

MainBoard: TP.VST59S.P89

IC MainBoard: CPU: TSUMV59XE-Z1, FLASH: W25Q32

CPU: R620D

Specifications LEA-32V24P
AKAI LEA-32V24P
General advice about LCD LED TV repair
Possible defects

- AKAI LEA-32V24P does not turn on, the buttons and remote does not respond, the indicators on the front panel are not lit or blinking.

In this case first of all you should check the functionality of the main power supply - AC/DC converter, all elements of which are located on the MainBoard TP.VST59S.P89. Then you should measure its output voltages and in case of their full or partial absence you should check the serviceability of power switches (MDF7N60B) and rectifier diodes of converters for possible short circuit.


If the semiconductors in the secondary circuits break down, the inverter can usually be short-circuited, and the mains fuse is often blown when a short circuit occurs in the primary circuit power elements.
Mos-Fet power switches used in switching power supplies sometimes fail due to the failure of some other element that can take it out of key mode, or create the maximum allowable parameters of the switch. These can be elements that feed the PWM controller, the frequency-retaining or damping circuits, or negative feedback elements in the stabilization circuit. PWM controllers LD7536 (PWM SOT23-6 ), in the absence of visible damage or outright short circuits between the pins are checked by replacing with new or known good.

- No picture, but there is sound and reaction to remote control commands. Or the image appears immediately after switching on and disappears.

Usually in such cases the defect is detected in the nodes of LED panel backlight. Often the cause of the malfunction is the lack of current in the chain of LEDs, such as their breakage or short circuit, or a violation of the contact connections of slots HL-17320A28-0801S-01.
It is impossible to detect a breakage in the line of LEDs without disassembling the panel with a simple multimeter. The LEDs are connected in series and to open their junctions you will need a voltage of several tens of volts. Ideally a current source would be suitable for this purpose. You can open up the panel and check each LED separately. Usually, Chinese multimeters will light up one 3 volt LED slightly if you connect the probes to it in the forward direction (red probe to the anode, black probe to the cathode). For twin 6-volt LEDs, the PN junction of its faulty regulator can be a good indicator. If the LED is faulty, its regulator will either be broken or it will be short-circuited.

If the AKAI LEA-32V24P has no picture but sound, often the T315XW04 V3 display backlight simply does not work. And, in LED TVs, the LEDs inside the panel usually fail, less often the LED driver.
In such cases you may see a faintly visible image when external lighting strikes the screen.

Disassembly of the T315XW04 LCD Panel is required to replace the LED's, a process which requires the technician's experience and expertise. We strongly advise against performing this operation by yourself if you own the TV and if you are not an experienced LCD panel repair technician.


READ HOW TO REPAIR THE TV LED BACKLIGHT --------------> HERE.

 
If there is no image, but backlighting works, the screen becomes a little lighter when the TV is switched on and you can see the light through the holes in the panel body when the TV is open.
In this case the panel may be defective - damage to the boards, cables, for example, as a consequence of moisture after an unsuccessful washing of the screen, the T-CON board (Timing Controller) may be defective. But it's not uncommon for the MainBoard TP.VST59S.P89 to be faulty as well, or for the software to be faulty as well.
The first thing to check is the panel supply voltage, fuses on the T-CON board, as well as the supply and voltage reference of the column and line drivers - VGH, VGL, Vcom.
If these measurements are within normal limits, you need to trace with an oscilloscope the LVDS signals from MainBoard TP.VST59S.P89, as well as synchronizing signals to the driver stubs.

Flooded or badly washed LED TV screens can be repaired in about half of all cases, usually if no significant damage has occurred to the panel stubs and strips.

- The LED blinks or lights constantly, the TV set does not turn on, the remote control does not respond.

Repair or diagnostic of the TP.VST59S.P89 motherboard begins with checking the regulators and power converters needed to power the chips and matrix. If necessary, software (firmware) should be updated or replaced. Board repair and chip replacement CPU: TSUMV59XE-Z1, FLASH: W25Q32 are made with the necessary equipment and the appropriate element base. Malfunctions associated with the use of soldering technology BGA processor can be localized by the heating method.

In case of the lack of tuning to the on-air or cable TV channels make sure that the software is correct, and also that the supply voltages on the R620D tuner pins correspond to the nominal ones. Also you have to check the presence of the tuner data exchange pulses with the processor via I2C bus with the help of an oscilloscope.

Once again, users must be reminded! Trying to repair your AKAI LEA-32V24P without proper skill and experience may result in its total unrepairability!


DOWNLOAD SCHEMATIC DIAGRAM  / SERVICE MANUAL   ------------------>    Service manual and sсhematic diagram TP.VST59S.P89


 Refinement after repair of the backlight. TP.VST59S.P89, OB3350CP. Information from the master.

To reduce the backlight current from 330 mA to 220 mA, I removed one of the low resistance 3.0 Ohm resistors in the driver current sensor on the TP.VST59S.P89 board. Located next to the LB802 coil.
Driver current limitation. TP.VST59S.P89, OB3350. Technical information

To reduce the backlight current in LED drivers with the popular OB3350CP (OB3350) controller, you must proportionally increase the total resistance of the current sensor - measuring low-resistance resistors from pin 5 (FB) to the body.
The TP.VST59S.P89 board has five resistors connected in parallel RB837 to RB842. Simply remove one or two of the resistors.

The driver may use the OB3350 chip. Then you can reduce the driver current with low impedance resistors in the LED circuit from the LED connector pins.


You can read & LEARN  more below:

Many TV manufacturers are now installing a questionable thermal rating for the backlight LEDs, which has a negative effect on the longevity of the device. In half of the cases, LEDs fail after 2-3 years of operation due to overheating, usually seen by the destroyed phosphor on the body of the LEDs. The warranty period, as a rule, the LEDs still have time to work out.

Even if the maximum allowable current is within specifications the cooling of LEDs is not always sufficiently efficient, which can be seen by the traces of overheating, i.e. dark spots on textolite slats on the back side. And modern LED televisions use diodes with an external phosphor coating, which after a year or two crumbles and the crystal directly shines purple. How such a source of ultraviolet radiation can harm the health of users, no one has yet thought.

Chinese manufacturers via Aliexpress supplies diodes and LED strips in kits of any assortment, but the lucky owner of the TV pays for them and for the repair.

After replacing one or more faulty LEDs, it is useful to look at the rest carefully, if the phosphor is cracked, it is advisable to replace all the LEDs. If you measure the voltage drop on overheated LEDs, it will be slightly higher than that of adjacent less worn or new LEDs, which indirectly indicates the presence of a parasitic active resistance (ESR). Further operation of such LEDs is even more questionable.


If you reduce the current in the diodes, the power dissipation and the real operating temperature will decrease, then there is a chance that the old ones will still work.


Ways to limit the current in LED backlight drivers:

There is a lot of information on the Internet about ways to limit the current in the LED backlighting for different TVs and LED drivers. A lot of it is written plausibly but sometimes it is written by people far from electronics in order to publish any popular content on hot topics to boost web-sites ratings.

It's impossible to talk about each case separately within one article, because even similar models may have different panels and different boards with their own driver variants. But there are basic principles that are clear to craftsmen with even minimal knowledge and skill.


Other popular, complex and controversial current limit cases will be published as information becomes available.
There are three basic ways to reduce the backlight current.

1. By increasing the resistance of the LED current sensor - a low-resistance measuring resistor in the cathode (LED-) circuit.
2. Increasing the ratings of the resistors on the ISET (current setting) input of the LED driver chip.
3. changing the resistor ratings in the divider on the ADIM (Dimming) control input.

The fundamental difference between input ISET and ADIM is that ISET - input inverted, as FB, and ADIM - direct.


A PDF document from the manufacturer of the -----------> OB3350 is attached

 
READ HOW TO REPAIR THE TV LED BACKLIGHT --------------> HERE.

More on MainBoard repairs

The MainBoard TP.VST59S.P89 is shown in the illustration below:




TP.VST59S.P89

The TP.VST59S.P89 motherboard is combined with a power supply module and is a standalone unit based on the TSUMV59Xx multifunction processor. The repair of such a card must begin with checking the power elements, as well as the efficiency of voltage converters and linear regulators, necessary to power certain processor parts, in particular: +1.2V core power supply, +1.8V on-board DDR memory and stand-by 3.3V stand-by unit. LCD panel supply voltage of 5V, or 12V depending on the type of panel used, is to be checked directly at the LVDS socket.

TP.VST59S.P89 can be used in televisions:

AKAI LEA-32A08G (Panel LC320EXN (SE)(E1)), AKAI LEA-28A08W (Panel ST2751A01-1), DEXP 32A3300 (Panel JHD315GH-E52), DNS H32A30 (Panel JHD315GH-E52), FUSION FLTV-32L42B (Panel KM315E3-CS-02), TELEFUNKEN TF-LED32S6 (Panel CX315DLEDM ST3151A05-5).

The main features of the device AKAI LEA-32V24P:

A matrix (LED panel) T315XW04 V3 or ST315A04-5 is installed.
A converter combined with the main board TP.VST59S.P89, controlled by a PWM controller OB3350CP, is used to power the backlight LEDs. A TO-252-type switch is used as a power element in the LED driver.
The power module is combined with MainBoard and is designed as reverse- path converter of AC/DC voltage with use of LD7536 (PWM SOT23-6 ) chips and MDF7N60B type power keys.
MainBoard - the main board (motherboard) is TP.VST59S.P89 module, with TSUMV59XE-Z1 CPU, W25Q32 FLASH and other microcircuits used.
The R620D tuner provides TV programme reception and channel tuning.


PWM SMPS in SOT-23-6, SOT-26, TSOP-6 packages

In the circuitry of modern switching power supplies (SMPS), PWM controllers made in small-sized planar packages with six terminals have gained wide popularity. The enclosure type designation can be SOT-23-6, SOT-23-6L, SOT-26, TSOP-6, SSOT-6. The appearance and arrangement of the pins are shown in the figure below. In this case, the code marking LD7530A is shown on the left fragment of the picture.


 

 Pin assignment:
1 - GND. (Common wire).
2 - FB. (FeedBack - Feedback). Input for controlling the duration of pulses with a signal from the output voltage. Sometimes it can be labeled COMP (input comparator).
3 - RI / RT / CT / COMP / NC - Depending on the type of microcircuit, it can be used for a frequency-setting RC circuit (RI / RT / CT), or for organizing protection, as an input of a PWM trip comparator at a threshold value at its input, specified in the document. In some types of microcircuits, this input may not be used in any way (NC - No Connect).
4 - SENSE, otherwise CS (Current Sense) - Input from the current sensor at the source of the key.
5 - VCC - Input voltage supply and start of the microcircuit.
6 - OUT (GATE) - Output for controlling the gate (Gate) of the key.

Functionally, these regulators work on the principle of the previously popular xx384x PWM microcircuits, which have proven themselves well in terms of reliability and stability.

Some difficulties often arise when replacing or choosing an analog for such PWM regulators due to the use of code markings in the designation of the type of microcircuits. The situation is complicated by a large number of component manufacturers who do not always provide documentation to the mass access, just as not all manufacturers of finished devices supply repair service centers with diagrams, so repairmen often have to study real circuit solutions by installed components and wiring connections directly on the board.

In practice, PWM microcircuits and the marking code EAxxx and Eaxxx are often found. Official documentation for them was not found in the public domain, but discussions on the forums and pieces of pictures from PDF from System General, which publishes them as SG6848T and SG6848T2, have survived. The drawing is here placed left .


 

For the attention of the masters, here below are PDF datasheet tables compiled from information available on the Internet and PDF documents for the selection of analogues types when replacing the most common six-legged planar PWM with pinout pins: pin1 - GND, pin2 - FB (COMP), pin4 - Sense, pin5 - Vcc, pin6 - OUT ...
Their main difference is the application and purpose of pin 3. 

 

NamePart NumberFabricantMarking
SG6849SG684965TZFairchild / ON SemiBBxx
SG6849SG6849-65T, SG6849-65TZSystem GeneralMBxx EBxx
SGP400SGP400TZ System General AAKxx

 

 PWM controllers (PWM) with a 95-100 kOhm resistor on pin 3.

When applying the PWM listed below, the frequency should be set with the RT (RI) resistor from pin 3 to ground. Usually its nominal value is chosen 95-100 kOhm for a frequency of 65-100 KHz. For more details, see the here below attached documentation. PDF files are packed in RAR.

 

NamePart NumberFabricantMarking
AP3103AAP3103AKTR-G1Diodes IncorporatedGHL
AP8263AP8263E6R, A8263E6VRAiT SemiconductorS1xx
AT3263AT3263S6ATC Technology3263
CR6848CR6848SChip-Rail848H16
CR6850CR6850SChip-Rail850xx
CR6851CR6851SChip-Rail851xx
FAN6602RFAN6602RM6XFairchild / ON SemiACCxx
FS6830FS6830FirstSemi
GR8830GR8830CGGrenergy30xx
GR8836GR8836C, GR8836CGGrenergy36xx
H6849H6849NFHI-SINCERITY
H6850H6850NFHI-SINCERITY
HT2263HT2263MPHOT-CHIP63xxx
KP201
Kiwi Instruments
LD5530LD5530GL LD5530RLeadtrandxxt30 xxt30R
LD7531LD7531GL, LD7531PLLeadtrendxxP31
LD7531ALD7531AGLLeadtrendxxP31A
LD7535/ALD7535BL, LD7535GL, LD7535ABL, LD7535AGLLeadtrendxxP35-xxx35A
LD7550LD7550BL, LD7550ILLeadtrendxxP50
LD7550BLD7550BBL, LD7550BILLeadtrend xxP50B
LD7551LD7551BL/ILLeadtrendxxP51
LD7551CLD7551CGLLeadtrendxxP51C
NX1049XN1049TPXian-Innuovo49xxx
OB2262OB2262MPOn-Bright-Electronics62xx
OB2263OB2263MPOn-Bright-Electronics63xx
PT4201PT4201E23FPowtech4201
R7731R7731GE/PERichtek0Q=
R7731AR7731AGERichtekIDP=xx
SD4870SD4870TRSilan Microelectronics4870
SF1530SF1530LGTSiFirst30xxx
SG5701SG5701TZSystem GeneralAAExx
SG6848SG6848T, SG6848T1, SG6848TZ1, SG6848T2Fairchild / ON SemiAAHxx EAxxx
SG6858SG6858TZFairchild / ON SemiAAIxx
SG6859ASG6859ATZ, SG6859ATYFairchild / ON SemiAAJFxx
SG6859SG6859TZFairchild / ON SemiAAJMxx
SG6860SG6860TYFairchildAAQxx
SP6850SP6850S26RGSporton Lab850xx
SP6853SP6853S26RGB, SP6853S26RGSporton Lab853xx
SW2263SW2263MPSamWin
UC3863/GUC3863G-AG6-RUnisonic Technologies CoU863 U863G
XN1049XN1049, XN1049TPInnuovo Microelectronics49 xxx

 

 PWM controllers that use pin 3 differently.

When using the following PWM (PWM controllers), you should pay attention to pin 3, which can be used to organize protection - thermal or from overvoltage of the input voltage.
The frequency can be fixed at 65kHz, or set by the value of the capacitor at pin 3.
When replacing any microcircuits with analogs, carefully study the documentation. PDF files are packed in a RAR archive.

 

NamePart NumberFabricantMarking
AP3105/V/L/RAP3105KTR-G1, AP3105VKTR-G1, AP3105LKTR-G1, AP3105RKTR-G1Diodes IncorporatedGHN GHO GHP GHQ
AP3105NA/NV/NL/NRAP3105NAKTR-G1, AP3105NVKTR-G1, AP3105NLKTR-G1, AP3105NRKTR-G1Diodes IncorporatedGKN GKO GKP GKQ
AP3125A/V/L/RAP3125AKTR-G1, AP3125VKTR-G1, AP3125LKTR-G1, AP3125RKTR-G1Diodes IncorporatedGLS GLU GNB GNC
AP3125BAP3125BKTR-G1Diodes IncorporatedGLV
AP3125HA/HBAP3125HAKTR-G1, AP3125HBKTR-G1Diodes IncorporatedGNP GNQ
AP31261AP31261KTR-G1Diodes IncorporatedGPE
AP3127/HAP3127KTR-G1, AP3127HKTR-G1Diodes IncorporatedGPH GSH
AP3301AP3301K6TR-G1Diodes IncorporatedGTC
FAN6862FAN6862TYFairchild / ON SemiABDxx
FAN6863FAN6863TY, FAN6863LTY, FAN6863RTYFairchild / ON SemiABRxx
HT2273HT2273TPHOT-CHIP73xxx
LD7510/JLD7510GL, LD7510JGLLeadtrendxxP10 xxP10J
LD7530/ALD7530PL, LD7530GL, LD7530APL, LD7530AGLLeadtrendxxP30 xxxP30A
LD7532LD7532GLLeadtrendxxP32
LD7532ALD7532AGLLeadtrendxxP32A
LD7532HLD7532HGLLeadtrendxxP32H
LD7533LD7533GLLeadtrendxxP33
LD7536LD7536GLLeadtrendxxP36
LD7536RLD7536RGLLeadtrendxxP36R
LD7537RLD7537RGLLeadtrendxxP37R
LD7539C GLLD7539C GLLeadtrendxxP39C
ME8204ME8204M6GMicrOneME8204xx
NCP1250NCP1250ASN65T1G, NCP1250BSN65T1G, NCP1250ASN100T1G, NCP1250BSN100T1GON Semiconductor25xxxx
NCP1251NCP1251ASN65T1G, NCP1251BSN65T1G, NCP1251ASN100T1G, NCP1251BSN100T1GON Semiconductor5xxxxx
OB2273OB2273MPOn-Bright-Electronics73xx
R7735R7735AGE, R7735HGE, R7735GGE, R7735RGE, R7735LGERichtek
UC3873/GUC3873-AG6-R, UC3873G-AG6-RUnisonic TechnologiesU873 U873G
 


Further technical information about this panel:
Brand : AUO
Model : T315XW04 V3 CELL
Type : a-Si TFT-LCD, CELL
Diagonal size : 31.5 inch
Resolution : 1366x768, WXGA
Display Mode : AMVA, Normally Black, Transmissive
Active Area : 697.685x392.256 mm
Surface : Antiglare (Haze 2%), Hard coating (3H)
Glass Depth : 0.70+0.70 mm
Contrast Ratio : 3000:1
Display Colors : 16.7M (8-bit), CIE1931 72%
Response Time : 6.5 (G to G)
Frequency : 60Hz
Signal Interface : LVDS (1 ch, 8-bit), 30 pins
Voltage : 12.0V

AKAI LEA-32V24P TV with ST315A04-5 LCD display, measuring 32" (81cm) diagonally in a 16:9 aspect ratio. This model features Edge LED side illumination.
The ST315A04-5 LCD panel and MainBoard software TP.VST59S.P89 provide HD picture quality at 1366x768 resolution in 720p (HD Ready). Input antenna or video signals can be processed in PAL, SECAM, NTSC analogue systems. Graphical processing and digital signal formation is done in 480i, 480p, 576p, 720p standards. Supported multimedia file formats are MP3, JPEG.
The 16W (2x8W) audio output is provided by two speakers. NICAM STEREO audio processing system is used.
External interface (connection with other devices) is supported by standard input and output connectors: antenna input (RF), VGA, USB. A VGA (D-Sub 15) connector on the TV cabinet is used to connect a computer or notebook computer to the TV, the interface supports resolutions: 640x480, 800x600, 1024x768, 1360x768.

The TV set uses the power supply as part of the MainBoard.

Its dimensions are: 736x483x180mm.

Warning. The panel ST315A04-5 of AKAI LEA-32V24P LED TV is an expensive and unreliable element.
Avoid any kind of impact on the glass and pressure on the surface of the screen to avoid damage to the LED panel!
It is also not safe to splash liquid on the screen. Sometimes a single drop is enough if it drips down the glass onto the cables and the television becomes unrepairable.