Hitachi TV won't turn on
#1
07-01-01, 09:00 AM
Was watching my Hitachi 27' TV the other morning and for no apparent reason "click", the TV went out,(picture and sound). The TV has been in the same location (in my bed room), for three years, and has not been moved. When I try (with remote or with the manual on/off) to turn the TV on, I hear a click, which is followed almost immediatly by another more faint sounding click, but no picture or sound.
I'm hopeful that there is a fuse or something that I could repair myself. Also I'm not sure how to discharge the high voltage from the set, is it like the older models where you take the probe out of the top of the picture tube and touch it to the chasie?
I'm hopeful that someone can tell me if I should attempt a repair, or if this Hitachi should now become a boat anchor. Many thanks in advance.
I'm hopeful that there is a fuse or something that I could repair myself. Also I'm not sure how to discharge the high voltage from the set, is it like the older models where you take the probe out of the top of the picture tube and touch it to the chasie?
I'm hopeful that someone can tell me if I should attempt a repair, or if this Hitachi should now become a boat anchor. Many thanks in advance.
#2
07-01-01, 02:07 PM
Good Afternoon, MAT:
Something has shorted in the set and the internal circuit breaker is kicking in to prevent you from trying to actuate the set any further.
Discharging the high voltage is not big job. Ground a long screw driver with a wire to chassis ground, slip the screw driver up under the "cup" of the high voltage lead on the picture tube, and you will hear a "SNAP". The high voltage is gone in that instant. If the set has been off for a couple of hours, it will be gone anyway.
The sudden loss of the set gives me cause to believe that a diode shorted in the power supply. That would be my first check. Second check would be the quadrupler module in the high voltage. Both of these are prone to sudden failures and both will give the same indication.
Either way, the back has to come off the set. I seriously doubt that you are going to get away from this one with just a change of fuse. The "click" you are hearing is a circuit breaker circuit and I doubt you will find a fuse to change.
Smokey
Something has shorted in the set and the internal circuit breaker is kicking in to prevent you from trying to actuate the set any further.
Discharging the high voltage is not big job. Ground a long screw driver with a wire to chassis ground, slip the screw driver up under the "cup" of the high voltage lead on the picture tube, and you will hear a "SNAP". The high voltage is gone in that instant. If the set has been off for a couple of hours, it will be gone anyway.
The sudden loss of the set gives me cause to believe that a diode shorted in the power supply. That would be my first check. Second check would be the quadrupler module in the high voltage. Both of these are prone to sudden failures and both will give the same indication.
Either way, the back has to come off the set. I seriously doubt that you are going to get away from this one with just a change of fuse. The "click" you are hearing is a circuit breaker circuit and I doubt you will find a fuse to change.
Smokey
#3
07-03-01, 04:48 AM
Hey Smokey,
Thanks for the expert help, I now have the set on its side, and have slide the chassie halfway out, providing access to both sides of the printed circut board, at this point I'm not sure that I've indentified the main power supply. There are two small transformers(power supplys) on the board, one is slightly larger, I'm assumeing that it's the one I want to test. Next question, how expensive is this part and how hard are they to locate? Also, I have no schematic for this set so are there standard readings(volt/ohms) that can be taken on the power supply to determine if it's OK.
Thanks for the expert help, I now have the set on its side, and have slide the chassie halfway out, providing access to both sides of the printed circut board, at this point I'm not sure that I've indentified the main power supply. There are two small transformers(power supplys) on the board, one is slightly larger, I'm assumeing that it's the one I want to test. Next question, how expensive is this part and how hard are they to locate? Also, I have no schematic for this set so are there standard readings(volt/ohms) that can be taken on the power supply to determine if it's OK.
#4
07-03-01, 06:34 AM
Good Morning, Mat:
Sometimes it is a litle difficult to identify the diode in question because they often house a complete bridge rectifier circuit (four diodes) in a single housing. Regular diodes are not difficult to identify because they are usually black and have the familiar sausage shaped body.
I will make the assumption that you are somewhat literate in the electronic business. Therefore, I recommend that you get a schematic on the unit so that you can identify the areas of concern. Things are like the old days when you could depend on power supplies to be grouped in one section. I suggest you contact Union Electronics on the web, give them your model and serial number, and I would bet they can find the necessary documentation.
Contact them at http://www.unionel.com
The cost of parts are minimal if it is a diode. Diodes are the least expensive component in the set (next to a resistor). Diodes are unique that they will only pass current in one direction. Thus a good volt-ohmmeter will be a necessary part of the trouble shooting.
Smokey
Sometimes it is a litle difficult to identify the diode in question because they often house a complete bridge rectifier circuit (four diodes) in a single housing. Regular diodes are not difficult to identify because they are usually black and have the familiar sausage shaped body.
I will make the assumption that you are somewhat literate in the electronic business. Therefore, I recommend that you get a schematic on the unit so that you can identify the areas of concern. Things are like the old days when you could depend on power supplies to be grouped in one section. I suggest you contact Union Electronics on the web, give them your model and serial number, and I would bet they can find the necessary documentation.
Contact them at http://www.unionel.com
The cost of parts are minimal if it is a diode. Diodes are the least expensive component in the set (next to a resistor). Diodes are unique that they will only pass current in one direction. Thus a good volt-ohmmeter will be a necessary part of the trouble shooting.
Smokey
#5
07-10-01, 01:20 PM
Hello MAT,
you didn't say what model# TV you have, or how old it is...
There are a number of possibilities with a dead TV symptom such as..... power supply diodes, bridge rectifier, low voltage regulator, 130 volt regulator(common failure component), Horizontal Output Transistor(another common failure component), Flyback Transformer, capacitors, etc...
The clicking that you are hearing is almost definately the Power Relay which clicks louder when energized and then de-energizes and clicks softer. It de-energizes due to the fact that the set has a problem and doesn't provide the neccessary feedback voltages which would keep the relay energized. This most likely isn't an easy repair for you, but it's worth a look, since you might find a broken solder connection. I wouldn't spend too much $$ on schematics if I were you, especially if you're unfamiliar with troubleshooting electronic circuitry.
Good Luck MAT!
you didn't say what model# TV you have, or how old it is...
There are a number of possibilities with a dead TV symptom such as..... power supply diodes, bridge rectifier, low voltage regulator, 130 volt regulator(common failure component), Horizontal Output Transistor(another common failure component), Flyback Transformer, capacitors, etc...
The clicking that you are hearing is almost definately the Power Relay which clicks louder when energized and then de-energizes and clicks softer. It de-energizes due to the fact that the set has a problem and doesn't provide the neccessary feedback voltages which would keep the relay energized. This most likely isn't an easy repair for you, but it's worth a look, since you might find a broken solder connection. I wouldn't spend too much $$ on schematics if I were you, especially if you're unfamiliar with troubleshooting electronic circuitry.
Good Luck MAT!
#6
07-10-01, 02:03 PM
Good evening, lucman2:
Bad advice. If the customer has the set disassembled and is looking into the circuitry, deal with the obvious. 99% of the time a diode shorted. Next would be a quadrupler module.
Chances are this is a simple fix. Having a diagram is not a bad issue when the person has the verve to work on the unit.
We are totally aware of the fact that there is a multitude of things that could shut down a television set. And, you and I have probably seen them all. Working from a technician aspect, we go into a set expecting the worst and come away feeling good that it was something simple. We feel good because it is an easy fix and we feel good that we don't have to charge huge repair charges to the customer.
The plan of this site is to give the working man an even break and prevent large charges. We try to give that person some incentive to make their own repairs and save all those dollars.
We try not to "snow" the customer with huge electronics and try to maintain some discipline on the repairs. We always remember the guy on the other end of this post is not adept at the project and does not have 40-60 years of experience on the bench. The "first timers" and the "do it yourselfers" are our friends and our reason for being here.
Don't muddy the waters. Keep it simple and keep it informative. Never make a comment against a product line that is not substantiated. Even though we know, personally, that a particular product line is problem oriented, we do not stress that fact. Nothing will turn off a customer faster than to hear we feel he bought a bad product in the beginning. They all feel they bought the best product and we honor that decision. The decision was not ours to make and the customer is the most important product on this site.
If you care to discuss this further, the email is
oldnavy1@blomand.net
Smokey
Bad advice. If the customer has the set disassembled and is looking into the circuitry, deal with the obvious. 99% of the time a diode shorted. Next would be a quadrupler module.
Chances are this is a simple fix. Having a diagram is not a bad issue when the person has the verve to work on the unit.
We are totally aware of the fact that there is a multitude of things that could shut down a television set. And, you and I have probably seen them all. Working from a technician aspect, we go into a set expecting the worst and come away feeling good that it was something simple. We feel good because it is an easy fix and we feel good that we don't have to charge huge repair charges to the customer.
The plan of this site is to give the working man an even break and prevent large charges. We try to give that person some incentive to make their own repairs and save all those dollars.
We try not to "snow" the customer with huge electronics and try to maintain some discipline on the repairs. We always remember the guy on the other end of this post is not adept at the project and does not have 40-60 years of experience on the bench. The "first timers" and the "do it yourselfers" are our friends and our reason for being here.
Don't muddy the waters. Keep it simple and keep it informative. Never make a comment against a product line that is not substantiated. Even though we know, personally, that a particular product line is problem oriented, we do not stress that fact. Nothing will turn off a customer faster than to hear we feel he bought a bad product in the beginning. They all feel they bought the best product and we honor that decision. The decision was not ours to make and the customer is the most important product on this site.
If you care to discuss this further, the email is
oldnavy1@blomand.net
Smokey
#7
07-11-01, 06:13 AM
Smokey,
....Lets talk about bad advice!
I tell it like it is...You, on the other hand, simply tell them a simple brushed-up diagnosis of what limited information you have and you seem to fill in the blanks when you're unsure of what your talking about...
...first of all... how can you suggest to MAT that there is a circuit breaker, when in fact, most TV's don't even have cicruit breakers in them these days, and besides, he didn't even supply you with the model# or the year of the TV set...
...Secondly, you suggested the Quadrupler Module..."what are you talking about???"...they seldom even exist anymore...it's called a Flyback Transformer and the voltage multiplier is incorporated into the Flyback.
...You say 99% of the time it's a diode????? If that was true, we'd all have very successful repair businesses -Who are you kidding? I've replaced more H.O.T.'s or Voltage Regulators than simple diodes....what kind of TV's have you been working on?...It doesn't even seem like you even work in the consumer repair field, do you????
Better yet, let's start a Pole with all the experienced Electronics Servicers and see how many agree with you...I seriously doubt they would support much of what you say.
Your suggestions seem a little out-dated if you ask me.
You say "keep it simple"...but nothing gets accomplished and they waste their time chasing a couple of components that may not even exist (how simple is that)???
I've seen your suggestions from past postings...and it's clear how limited your knowledge is, in the field of consumer repair.
I say...provide MAT and all the other folks with as much "correct" information as we can and wish them the best of luck.
[Edited by lucman2 on 07-11-01 at 02:29]
....Lets talk about bad advice!
I tell it like it is...You, on the other hand, simply tell them a simple brushed-up diagnosis of what limited information you have and you seem to fill in the blanks when you're unsure of what your talking about...
...first of all... how can you suggest to MAT that there is a circuit breaker, when in fact, most TV's don't even have cicruit breakers in them these days, and besides, he didn't even supply you with the model# or the year of the TV set...
...Secondly, you suggested the Quadrupler Module..."what are you talking about???"...they seldom even exist anymore...it's called a Flyback Transformer and the voltage multiplier is incorporated into the Flyback.
...You say 99% of the time it's a diode????? If that was true, we'd all have very successful repair businesses -Who are you kidding? I've replaced more H.O.T.'s or Voltage Regulators than simple diodes....what kind of TV's have you been working on?...It doesn't even seem like you even work in the consumer repair field, do you????
Better yet, let's start a Pole with all the experienced Electronics Servicers and see how many agree with you...I seriously doubt they would support much of what you say.
Your suggestions seem a little out-dated if you ask me.
You say "keep it simple"...but nothing gets accomplished and they waste their time chasing a couple of components that may not even exist (how simple is that)???
I've seen your suggestions from past postings...and it's clear how limited your knowledge is, in the field of consumer repair.
I say...provide MAT and all the other folks with as much "correct" information as we can and wish them the best of luck.
[Edited by lucman2 on 07-11-01 at 02:29]
#8
07-13-01, 04:04 PM
Advice
Let's look at this from my point of view. Lucman you never did answer my question. Please advise us/ME of your qualifications. I did in detail to be allowed to moderate here. I do not post at every question but I always see what's up... You are giving advice that I do not agree with. Do you realize that Smokey has forgotten more about this field that you, me and at least a dozen others put together will never know. I am not going to stand for this contest of who knows more! In my opinion and after 2000 plus posts most others will agree, Smokey is the definitive master of this forum and several others. I am not attacking you nor am I trying to stop you from posting your opinion but when it comes to this field you are dealing with one of the masters in Smokey. If you notice, I have been around the forums for awhile, I was approached by the owners of this forum because I give and so do the others here, information that an average Joe can understand. Most of the folks here are Do it yourselfers to a point, if you get over their heads then this is a forum for only those of us that are college/hands on trained. I will not stand by while you attack one of our most knowledgeable members when you refuse to answer even my most base questions. What is your background? How long have you been in the electronics business? Where did you train? Are you currently a bench tech? For what company? (Not by name but are you a warranty station for any major brand? The test of any bench tech is if you can get a warranty contract from a major company. Had you been in this game for awhile you should know this.!!!) I refuse to have a senior member (not age but knowledge) questioned by another member, and a new member at that. Come on man. Let's not make this a contest! But I reiterate! I will not stand by for a testosterone contest and I do believe that the master of this forum will back me. Mike.
