Tip & How-To about Televison & Video

Projection TV troubleshooting techniques.

When you turn your television on and get nothing almost anything could be wrong with it. The two most likely places to look are the high voltage section and the low voltage power supply. In order I will explain what to check to try to resolve the problem.

First, is the standby light blinking in some sort of pattern? If so, count the number of times it blinks between long pauses. If it is blinking in a patten, this is an error code, and can be helpful in diagnosing the problem. Depending on the manufacturer the blinking pattern will mean different things. Error code lists are available by googling "(manufacturer) tv error codes". Proceed from here based on the information provided by the error code list.

First for safety unplug the unit. If your set has no blinking lights proceed by checking the main fuse in the power supply for continuity and replace if open. Then proceed to looking at the mainboard for burned resistors or bulging electrolytic capacitors. Electrolytics look like little cans, with shiny ends and are generally black, grey or blue. They have a positive and negative lead so be careful when replacing to get the polarity correct. If they are bulging replace them. Also replace any bad resistors found. At this point it would be a good idea to inspect all solder joints on all boards, but especially the Low Voltage and High Voltage sections, and resolder anything which looks suspicious.

Finding no charred resistors or bulging caps, and after resoldering all connections, your unit still does not work, check the horizontal output transistor for failure. Using a DMM on diode check, check the transistor out of circuit for shorts/opens between any two leads. A good unit should have somewhere between 500 and 1000 ohms one way and infinity when the leads are reversed. Only two lead configurations will show conductivity. One set of leads should show infinite resistance both ways. If the transistor checks bad, replace it and the flyback. Check all resistors and diodes in the HV circuit and replace any suspicious units.

If the horizontal output transistor checks OK, check all semis in the LV power supply. Replace any bad units found and check all associated resistors and replace as necessary.

If both the HV and LV sections check OK, remove the circuit board from the CRT and try the unit. If it runs your CRT is bad and needs replaced. If it does not run your problem is elsewhere.

Working one section at a time, remove and isolate any remaining sections while attempting to turn unit on. If unit works with a particular section disconnected, your problem is in that section and you will need to do normal troubleshooting procedure, listed above, on the section in question.

If after all the above procedures are tried, and your unit still isn't working, you may have to replace an entire board. These days most boards are relatively inexpensive. The most likely board would be the LV power supply which usually contains the HV power supply also.

Any parts or boards needed can be ordered at http://www.encompass.com or http://www.shopjimmy.com .

Good luck with your troubleshooting and be careful while inside the set especially near the High Voltage second anode where it connects to the CRT.

Thanks for using FixYa and the great rating.


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1 Answer

When turned on and sometimes when turned off, why does it make a loud crack or arcing noise?

Usually, this problem is seen on CRT sets, not flat panels. Nut sometimes the category description here is wrong, so I will go on in general terms regardless. The crack is usually an electrical arc. CRT televisions have a high voltage section that supplies various voltages to the picture tube. When the set is operating these voltages have a place to go. When you power on and off, there is a short period of time when the potentials have no where to go until all the remaining circuits power up. This can cause arcing. There are safeguards in place to prevent this, but there are two things that can occur to bring on this issue. The first, and most common, is dust and dirt. Electronics are a dust magnet. Over time, dust and dirt collect on the circuit boards. This can break down the dielectric resistance and allow current to jump from one place to another (arcing). The other issue is that is the bleeder circuit that allows the high voltage to drain off after power has been removes malfunctions, then the high voltage takes longer to drain off since it has to find other paths to dissipate. This can result in an arc as well. I would have someone who is knowledgeable open and clean the interior of the device first to see if that alleviates the problem.

Dec 10, 2015 | Hitachi Televison & Video

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How to fix a Sony Trinitron?

the high voltage was shutdown the high voltage exceed to 33k volt which goes to safety mode.you will need to check the regulator in the power supply and the horizontal output transistor.

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1 Answer

i took the back panel off my tv and am trying to figure out if anything is wrong with my tv. i have no sound and no picture. Tv however does turn on. is there anything i could look for to see whats wrong?

Look for bad capacitors in the power supply, also look at the connectors, some of them may be labelled with the voltage rating, check to see if you have those voltage as indicated on the board.
Be careful, high voltage is present on board, you should plug the TV in the GFCI outlet when you are trying to work on it!

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Check for voltage at the end of your power cord. If you find voltage there next check for voltage on the other side of your glass type fuse.This will most likely be your problem.

good luck-------------------------tomtaso

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Your set is going into high voltage shut down. Might have been the high voltage transformer that has gone bad.

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