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Regulated Power supply

Replaced IC power regulator 2 times always blown out,what is the cause of this? can you help me please.

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  • iskwik Mar 15, 2008

    Sony Trinitron KVG21M2

    chassis # BG2S

    thank you for your good help maybe someday i can help you too.

  • Jaime Hernandez May 11, 2010

    Can you give us more info, model and chassis number of TV?


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If the regulator is being shorted right after you replace it, I would say that you have a polarized part that is doing that. I would suggest to check all the diodes and capacitors around the power supply circuitry, There is a posibility that T601 is shorted internally, also check IC603 for s shorted condition..
Check this picture for the power supply schematic.Regulated Power supply - d4d913d.jpg

Posted on Mar 16, 2008

  • Jaime Hernandez Mar 16, 2008

    Check Q561, Q801(H.Drive), Q802(H. Out) as well.


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1 Answer

My panasonic the fuse was blown out the cap 200v 560 mf and a resistance 1 ohm 7w i replaced them and the tv won't turn on

This is fairly straight forward---if it got the fuse, input filter (big cap!) and the fuseable 7 watt-----

Understand (I do not know how savy you are) the power supply uses two grounds----on the primary side of the transformer (in power supply) it is from earth ground and on the secondary side from hot ground--when checking voltages= these are the key! you have to be on the correct ground to get correct readings.

Follow the money---the primary raw should be on that cap---follow it to see when it stops downstream.

220 can pop a lot of things---the set should also have a regulator IC in the power supply (could also be a big transistor) and if a chip--raw from that cap goes into it---and regulated comes out another pin---see if you have the raw and then see if at horizontal output collector and from there to flyback( with set off what is resistance reading from the collector of the output transistor to earth ground?

what kind of experience do you have with troubleshooting?

Mar 22, 2012 | Panasonic CT-32SL14 32" TV

3 Answers

No Display, no sound- not working, showing dead. But input Power is ok. Picture tube filamment not getting power. model sony KV-2192M3

Check the input fuse first. If it is blown, there will be some short inside the power regulator circuit. Usually Sony sets uses STR regulated power supply. You can see this STR, and Ic, screwed onto a heatsink. Replace it with a same type and number. Before replacing the STR, check the diodes used in that section for damage, mainlu zener diodes. They might get shorted along the blowing of the STR. Check that section throughly before resoldering the new STR.
If any further assistance you needs, get me through Fixya. Ok.

Nov 27, 2010 | Sony FD Trinitron WEGA KV-21CL10 21" TV

2 Answers

When I turn my KV-34XBR800 on, the picture will not come on and the standby light keeps on blinking 7 times each time.

Seven blinks of standby led in Sony sets denotes a High Voltage Shutdon proble. It is a self diagonosis process of the microcomputer Ic inside it, which senses the high voltage and shuts down the whole system to prevent it from further damages. The high voltage means that not the high line voltage of your househod supply, but the voltage inside the circuit board of the TV exceeds more than normal. Your tv, being 34", have a high tension voltage of 32,000VDC at the final anode of the picture tube. This voltage depends on the main regulated voltage goes into the circuit board from the power regulator system. There is a power regulator built sytem inside your TV, to regulate the voltage send to main board, which bears the Line Output Transformer [LOT], which in turn generated the above said high voltage. The normal regulated voltage going to board may be around 135VDC, to a 34" tv. Even a rise in, say, 2 voltage more than normal may cause high voltage to rise up considerably high enough to get it shut off. Soney sets are normally have STR regulated power supply system. It is very accurate and durable. The main fault comes to it is soldering trouble. The above said STR regulator may rise to as high as 90 degree centegrede when working. Repeted heating and cooling, make the soldering on its legs to get loose contacted; causing improper regulation process. Your tvs case must be so.
You just open your TV, and find out the regulator section inside it, where the AC input voltage goes into. Just pull it out and resolder all suspected points by applying a little more solder; as exact bad solder point is very difficult to locate. We in service field also does this. 90% sure that this will retify your problem.
Take proper care before opening your TV. Keep in mind that you are going to work with an electrical equipment, which have as high as 32,000VDC poins are inside it while working. Take all precautions. Keep children away from you while you works. Never allow them even stand beside you Ok.

Nov 09, 2010 | Sony FD Trinitron WEGA KV-34XBR800 34" TV

1 Answer

TV won't turn on, standby light blinks seven times over and over

Seven continous blinks denotes that your Sony TV has some high voltage more than normal inside its final anode of your TVs picture tube.. When high tension volltage exceeds abve 33KV [33,000VDC], to the final anode of the picture tube, TVs microcomputer Ic will detect it and get it shutdown, to prevent it from further damages.

You have to check its power regulator section for this fault. Usually Sony TVs uses STR regulated power supply regulation in their TVs.
You must open the back cover of your TV, and locate the power regulator section, sometimes be as in a seperate board or in the main board itsef. Check for any loose solderings it it. As components in the power regulator system will heat up during working. As it heats up and cools down for several times, some loose soldering may occure in it, and is usual. It is difficult to locate the exact point of loose, and is risky too, as the power supply regulation side is directly connected to mains supply and will always be "Hot", so i recomends you to resolder all the points, especially the points of high watt resistors in it. Resolder the the STR legs also. Sometimes the STR itself may need replacement. If so go for the same number and type. This might retify your problem.
Normally Sony 32" TV has a working voltage between 125 to 140vDV, at the secondary side of the power regulator. It it exceeds this type of problem will occur.
Take all precautions we take when work with an electrical equiments. Keep chlidren away from you, and note even stand beside you when you do works. Keep an adult beside you as a precatiounary measure. As high as 27KVDC [27,000VDC] points are there inside your tv, while it works. Take care. Never use metal a metal chair. Ok

Oct 26, 2010 | Sony FD Trinitron WEGA KV-32FS120 32" TV

1 Answer

TDA3653 keeps blowing when the TV is switch ON

Without checking components associated with the TDA3653, the exact cause is impossible to say.
This IC has extensive built in protection circuitry that should protect it from overloads caused by such things as shorted turns in the vertical deflection coil, or from faults with any associated components, e.g. open/shorted resistors/diodes/capacitors.
The following data sheet describes this IC in detail:

Therefore as the IC keeps failing at switch on, and if no other components are failing or suffering damage, suspicion must fall on the supply voltage delivered to Pin 9 and Pin 6 being excessively high (or spiked) and thus causing a rapid demise of the IC. As most LV (low voltage) supply voltages in TVs are derived from a common regulated source, this would imply that the power supply circuitry itself may be faulty - dried out electrolytic capacitors being prime suspects.

However, as with any fault in complex circuitry such as this, there may be other causes including less logical ones such as dry joints or shorts in wiring or between PCB tracks.

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Dead Set after power surge

Check the power supply transformer primary driver transistor and the associated components (some diodes and capacitors, resistors, an optocoupler maybe) and the rectifier diodes (or a bridge) and capacitors at the transformer secondary, what you are looking for is a short circuit, however, the short may as well be in another section of the circuit board (a shorted component may sometimes have signs of damage caused by heat, but this is not a rule).

Hope you can find out what it is...



Oct 01, 2009 | Standard (CRT) Televisions

1 Answer

RCA TV blown fuse


you have bad Rectifier Diode or Ic regulator.. check first the unregulated power supply before you go to regulated power section! then check,.


Oct 23, 2008 | RCA F27242GY 27" TV

1 Answer

No screen on/no power to tv

1. Check whether the fuse in the Tv is blown or not. it may be located before the SMPS power unit.
2. if fuse is ok,then there might be problem with ur regulated power supply. Check for 110 voltage before the SM transformer
3.Check whether the EHT is working properly
4. these must be done by authorised service personnel.
5. No rectification from user part without the knowledge of servicing. More caution

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1 Answer

Sony KV-29-SN21 TV power supply clicks, no picture no sound

DO NOT PUT ON TV As it is DANGEROUS call tv tech to check high output in regulated power supply

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I would start with C869 a 2.2 Uf at 200 Vdc in the power supply. I have replaced a fair share of those in these sets. Of course the first thing to check would be the pico fuse in the power supply regulation circuits F860 a 4 Amp Pico Fuse and if it is blown, you will have to replace Q801 the Regulator IC Str-Z4214 Part # 23906369. If you're not that good at soldering and measuring capacitance and resistance, this would be a job for a more experienced tech.

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