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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Tuesday, 26 February 2019

LG DIGITAL BUS CHASSIS. NO PICTURE. NO SOUND . NO STANDBY LIGHT [LG DIGITAL BUS CHASSIS TVs. [USED ICs- 5W973CD0 & LA76810]

LG DIGITAL BUS CHASSIS. NO PICTURE. NO SOUND . NO STANDBY LIGHT [LG DIGITAL BUS CHASSIS TVs. [USED ICs- 5W973CD0 & LA76810]

The fault is with power supply regualtor section.

The power supply section of this TV, is transistorised SMPS,
Possible cause of power supply failure.

[1] Main rectifier diodes [shorted].  If rectifer diode has been shorted, it will blow up the fuse too.  so if the fuse is found opened, check these diodes first.

]2] PTC short.  If positive thermistor connected to degaussing coil shorted, the fuse will blow up.

[3] C902 & C901 [disc ceramic capaitors connected in parellel with two main rectifier diodes] short.  the fuse will blow up.

[4] Q904 [D2498]; main switching power transitor short [collector to emitter].  fuse will blow up.

[5] C821 [2K7 PF 2KV] connected to main ground and SMPS ground short. Fuse will blo up]

If blown up fuse noted, never insert an other fuse, until the fault has been detected and rectified.
When SMPS supply section is under suspection, check this section only after isolated it from the rest of the circuit. Replace all the transistors [both small signal transisors*3 and switching power tranistor] at the same time.  If C906 [47MFD] electrolytic capacitor connected to the base of the main switching power transistor is faulty, the power regulation to the SMPS will be poor, resulting low or high voltages at the output. Repalce this capacitor and D912(9V Zener diode) too.

Check the resistance value of [R917-39 Ohms 5W] & Capacitiance value of [C917-2K2Pf 2Kv].  If any one among these two components have any fault, the power sitecing transistor will blow OFF as soon as you switch ON it.

The two voltage outputs from this power supply section are 110VDC  and 20VDC.