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 REPAIR POWER SUPPLY FAULT TO [JVC - AV 21JT5EU & AV - 14JT5EU]


HOW TO REPAIR POWER SUPPLY FAULT TO [JVC - AV 21JT5EU & AV - 14JT5EU]


DEAD SET. 

    Troubleshoot should startup with AC mains power cord itself.  Just check the two conductors of the power cord for continuity.  Can check it continuity by using a multimeter set to Ohms range.

    In these sets, AC mains power is passed through a fuse [galss cartidge type]; can be located at the main power reulator section.  The fuse is marked [F801 - AC 250V 4 AMPS].  Check this fuse first.  If it is found opened, never insert an other fuse with same rating.  There will he some reason for the blow out of this fuse. 

    Set the multimeter to measure Ohms range.  Measure the reistance across capacitor [C801 - 0.47MFD AC250V].  The meter should measure a very high resistace.  If it show very low resistance, make sure that some short circuit is there at the AC input circuit. 
Check the load reisistor [Negative] (R802 - 3.3Ohms 7W).  If this reisistor found open, check the four mains rectifier diodes [D837_D838_D839 & D840].  If any one among them has junction short, the mains fuse and R802 might get damaged.  It is best to replace all these four diodes. Four of them are [LT 2A05G].  You can use any rectifier diodes, such as 1N4007 or so. 

    Desolder out [L802] and check the resistance across [C805 - 100MFD 400V _ MAIN DC FILTER].  If resistance acorss this capacitor is found very low, must check all the four rectifer diodes and four disc ceramic capacitors connected in parellel with these four diodes for leak. Still the multimeter reads low resistance across [C805], check the freewheeling capacitors (C842 - 1000Pf 1KV & C807 - 2200Pf 1.5Kv ). These two capaciors are of special types, and replacement must be done with capcitors have similar characteristics.  It might be leaky, and will be the fault for the blown up fuse.

If all said above components are OK, and there is no short circuit measured with multimenter, after desolder out [L802], make sure that the main switching MOSFET [ Q801 - SK2671] is faulty. check the resistance between the source and drain leads of this MOSFET.  If the MOSFET is good, there should be very high resistance in one direction.  If it shows very low reistance in both directions, the MOSFET is damaged. 

If the set do not switch ON, even if all the above components are good, and Fuse is Ok, check the two resistors connected in seris to the Gate of the swiching MOSFET and AC input line.  These two reistors in series, supplies the start voltage.  If any one among them is open, there will be no start voltage to MOSFET.  The start supply voltage to main switching control IC [I802 - DPM001TIA], pon number (5) too get through these reistors. 

There are five output voltages from the secondary side of the SMPS transformer.  133VDC, 45VDC, 16VDC, 12VDC & 5V regulated DC].

When work with power supply section of this set, tempeorarly desolder out [Q802 - KSA 1013Y].  Replace it only after all work has been done. 

On the secondary side of the SMPS transormer, not much fault has been detected.  The only fault found so far is the failure of protection zener diode [D835 - R2M]. 

Check all the solder terminals of components, which will heat up during working.  If any dry solder is detected, desolder them by applying a little more fresh solder.  It is a good practice to resolder all the suspected solder terminals-

 JVC AV-21JT5EU CHASSIS CP-005 / JVC AV-14JT5EBU, AV-14JT5EU, AV-21JT5EBU, AV-21JT5EU-A
MODELS: Daewoo 14C3, 14C3T, 14C3BL, 14C3EG, 14C3NTBL, 14C3NTEG, 14C3T, 14C4, 14C4T, 14C5, 14C5T, 14U1, 14V1, 14V2, 14V3, 14V5, 20C4, 20C4T, 20C5, 20C5T, 20U1, 20V1, 20V3, 20V4, 20V5, 21C6, 21C6T, 21U1, 21U3, 21V1, 21V2, 21V3, 21V4, 21V6, DTA-14C7TA, DTA-14V5TUFS, DTA-20C7TA, DTA-20C9TAS-S, DTA-20V1TAS-S, DTJ-28G7F, DTJ-28G8F, DTP-14C3, DTP-14C3TF, DTP-14C4, DTP-14C4TF, DTP-14C5TF, DTP-14M5TF, DTP-14V1, DTP-14V1TF, DTP-14V1TFE-S, DTP-14V2, DTP-14V2TF, DTP-14V3, DTP-14V3TF, DTP-14V5, DTP-14V5TF, DTP-20C4, DTP-20C4TF, DTP-20C5, DTP-20C5TF, DTP-20C5TFD, DTP-20C9TFD-S, DTP-20V1, DTP-20V1TF, DTP-20V1TFD-S, DTP-20V3, DTP-20V3TF, DTP-20V3TFD-S, DTP-20V4TF, DTP-20V5TF, DTP-21C6, DTP-21C6TF, DTP-21V1, DTP-21V1TF, DTP-21V2, DTP-21V2TF, DTP-21V4, DTP-21V4TF, DTP-21V6, DTP-21V6TF, GB20C4T, GB20C5NTS, K14C3T, K14V4T, K20C4T, K20V4T, K21C6T
Posted By: FRANK at 04:37
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