REPAIRING AND NOT THROWING AWAY

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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..............The bitterness of poor quality is remembered long after the sweetness of todays funny gadgets low price has faded from memory........ . . . . . .....
Don't forget the past, the end of the world is upon us! Pretty soon it will all turn to dust!

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Tuesday 26 February 2019

HOW TO TROUBLESHOOT - SONY TRINITRON – KV-1404M3 [NO POWER]

HOW TO TROUBLESHOOT - SONY TRINITRON – KV-1404M3 [NO POWER]

No standby light.  Set dead. AC fuse blows out as soon as set is switched ON.

The fault is with its main power regulator section.  There is some direct short circuit to either its rectifier section or switching section.
SMPS switching is done with [STR 50115B]
  Start troubleshooting with its main rectifier section.  AC is rectified by a bridge rectifier ( D601_ KBU4JL-6088).  Check this rectifier for any internal diode short.  If there is any shorted diode junction inside the rectifier diode. Protection fuse (f601_ 3.5Amps) will blow out, as soon as you switch on the set.
Before starting trouble shooting to power supply section, it is recommended to connect a filament type 100W bulb, in series with power in.  It can be done very easily.  Take out the glass cartridge type fuse from its holder.  Connect two wires on both end of the fuse holder and connect the other end of these wires to an ordinary bulb holder, with bulb.
By doing this, we are inserting a series resistor [resistance of the filament of the bulb] with power supply input.  If there is any short in the circuit, it can be detected by the intensity of light comes from the bulb.  Normally, if the switch mode power supply works well, the bulb will light up wit high intensity at first, when we switch ON the set by its main power switch, and will come lesser intensity, after the switch mode section has been attained stability.  If the bulb glows with full intensity, make sure that there is short-circuited component/s at the power rectifier or power regulator section.
The first thing to do, is to desolder out the switching device, STR50115B from circuit.  Without it, switch ON the set.  If bulb starts a blink, and goes OFF, the STR 50115B is faulty.  It is shorted internally.  This is a common type of fault with these sets.
 This STR has 5 solder terminals. The normal voltages to these terminals are:
1 = Ground (0V)
2 = Start base drive voltage (117V)
3 = Collector supply voltage to internal switching transistor (Depends on AC input voltage; as this DC voltage can vary with AC input voltage)
4 = Voltage out to main board (116.5VDC0 [Steady stabilized]
5 = Reference voltage (6V3)
Here, pin number 3 & 4 of the STR should be checked with a multimeter set to measure Ohms range.  If the meter shows approximately (0 or very low resistance up to 20Ohms); make sure that the collector to emitter junction of the internal switching out transistor is leaky, and the STR is defective.
Before replacing this STR, check and replace [9C608 _ 560pf 2Kv].   Even though this capacitor is a low value one, function of it when STR starts it switching process is very great.  Check and replace the protection zener diode [8608 _ R2m _ 120V-zener] too.
If STR is found defective, check the main rectifier stalk too.  It will be best to replace it too. 
Caution; Before starts troubleshoot, desolder out the degaussing posistor [THP 601 PTC].  Resoled it only after all works on power board has been completed.
If the power supply switching section is OK; when you switch ON the set by its power switch, the bulb connected in series, will light up at high intensity at first, and will go down to low intensity, and will remain steady.  But the set wont work properly as there will be insufficient AC voltage in due to the introduction of the filament of the bulb in series.  Now you can replace the bulb with a fuse in place.
 If (R604 – 470K) is open, the power supply start up.  It supplies the start up voltage at first when we switch On the set.  So if you feel any start up problem, replace this resistor.
Posted By: FRANK at 06:06
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