AWA TV model W571 - blue screen with white stripes

[stoney]

hi my awa tv model w571 has blue screen with white stripes. It's been to repair shop 3 times in last 10 days and still not working. It was suggested to me by someone else that placing a wire wrap around the flyback might solve the problem.When suggested to technician he siad no. What else could be wrong?

 

[banjo]

A bright blue screen with widely spaced white lines means the blue gun in the picture tube is running full on. This is either a detect on the video driver board or a picture tube defect. As the set ages, oxides can form in the guns of the picture tube. If the oxide forms a bridge across the elements, the picture tube will display these symptoms.
The repair shop should have easily been able to troubleshoot the cause. Does the set work again when you get it back? Does the set work for a short time and then go blue?
My wild guess is that they are trying burn out the oxide with a picture tube rejuvenator and it has not been successful. Sometimes this works, and sometimes it does not.

--- Steve

 

[stoney]

hi
yes on the repair warranty it made reference to a blue gun. Yes when i've got it back it works ok for a while then goes again.
He says its an intermittent problem. Not much good to me!
i read something about a rejuvinator somewhere else and they said that usually doesn't work. They also mentioned something about a wire wrap around the flyback.when i mentioned that to techniciam when he picked up tv for the 3rd time!!!!!!! he said his testing didn't indicate any form of short to the cathode.

Thanks for replying to my original post!

 

[banjo]

The wire around the flyback is probably useful only for a heater to cathode short. Probably the technician has found that the short is between the control grids and does not involve the cathode directly.
Rejuvenating to remove a short works some of the time. It is worth a try. However, it should be done with the tube resting on its face. That way any dislodged particles are carried by gravity down into the bell of the tube where they cannot do any harm.
I have also been able to tap out some shorts with a plastic brush handle. This is somewhat dangerous, so do not attempt it yourself or if you do wear safety glasses and a heavy jacket. The idea is to again place the set on its face and operate it until the screen goes blue. Once the oxides are causing the short, the neck of the tube is tapped with the plastic brush handle to shake the tube elements and dislodge the particle. The danger is two fold. First, the tube is operating so lots of high voltage is present. Secondly, the tube is under high vacuum, if you tap too hard, the tube could implode and throw off glass fragments. When successfully tapped, the screen will immediately return to normal.
I would question the repairman as to what methods they tried so far. If they have already tried the above, then assuming that the warranty on the picture tube has expired, I would start looking for a new TV. Unfortunately, the replacement cost of the tube is usually more than another set.

---- Steve

 

[stoney]

The wire around the flyback is probably useful only for a heater to cathode short. Probably the technician has found that the short is between the control grids and does not involve the cathode directly.
Rejuvenating to remove a short works some of the time. It is worth a try. However, it should be done with the tube resting on its face. That way any dislodged particles are carried by gravity down into the bell of the tube where they cannot do any harm.
I have also been able to tap out some shorts with a plastic brush handle. This is somewhat dangerous, so do not attempt it yourself or if you do wear safety glasses and a heavy jacket. The idea is to again place the set on its face and operate it until the screen goes blue. Once the oxides are causing the short, the neck of the tube is tapped with the plastic brush handle to shake the tube elements and dislodge the particle. The danger is two fold. First, the tube is operating so lots of high voltage is present. Secondly, the tube is under high vacuum, if you tap too hard, the tube could implode and throw off glass fragments. When successfully tapped, the screen will immediately return to normal.
I would question the repairman as to what methods they tried so far. If they have already tried the above, then assuming that the warranty on the picture tube has expired, I would start looking for a new TV. Unfortunately, the replacement cost of the tube is usually more than another set.

---- Steve

Hi,thanks again for replying,am beginning to think ur right re new set this one's only 14 months old and yeah replacing the tube is expensive and not economical.
Here's what was written on the original repair warranty (which is now 12 days old of it's 30 day lifespan!):-
Dissasembled unit,trace failures to picture tube and tube socket
Dislodge internal foreign material creating heaters to cathode,short circuit on blue gun
repair tube socket on neck ''plater'' circuit board.
replace heater dropping resistor and check plater circuit.

** note I could be wrong re ''''plater'' it's a bit hard to read the handwriting.
Thanks again for replying - appreciated.
I get the impression he doesn't like to be told or suggested what to do re rapirs and i figure if i get him on the wrong side he'll just put my job to the end of the queue,so feel asthough i am in a no win situation.
It is frustrating that it works for a short while each time he's brought it back to me then goes again but as soon as he takes it back to the shop it seems to go ok again. I wonder if he's telling me the truth??How would I know. From people i've spoken to he does seem to have a fairly good reputation around town.
Thing is how long do I wait? What happens when his warranty runs out,like i said it's only for 30 days and it's 12 days old already. Is that what he's aiming for that it will run out so I have to pay him again? Sounds cynical I know but hell it's been almost 2 weeks now and out of that time i've had use of he tv for only 4 days!Just not good enough.If i take it to another techo then i ahve to pay all over again.
Can't even report this guy to office of fair trading because he is at least trying (I presume!) to fix the problem.He says its frustrating for him aswell as me.
Today he informed me he has faxed the manufacturer for info.Now I don't know if that's a good sign or not?!Is he really trying to get this fixed or is it a case of he doesn't know what to do and everything he's told me so far is just a case of stringing me along?!
You'd think a brand new tv would last more than 14 months ffs!?! Right?
Thanks for replying,you can send direct reply if you like to owenjay@netspeed.com.au
cheers
john

 

[banjo]

John,

If the set is only 14 months old, then there is a good chance the picture tube is still under parts warranty. I would take the set back to the repair shop and ask who to contact about the warranty on the picture tube. Tube warranties have been dropping every year, but they are still typically at least 2 years. Ask for the phone number of the manufacturer's area representative. Call this person and politely tell them that you are extremely disappointed in the performance of their product.
If the manufacturer had a bad run of tubes, they will usually replace them for the customer's that complain. Sometimes they will cover parts and labor to make the customer happy. Other times only the parts. Typically, the bench charge for replacing a tube is about 2 hours since numerous adjustments are required. You would have to pay this labor charge, but it should be much cheaper than a new set.
Make sure the repair shop understands that if they can help you get the tube under warranty, then you will pay the install labor. Otherwise, they really do not have a big incentive to help you.
The reason for taking the set back immediately is two fold: first, it not really useable to you. Secondly, when it is taking up shelf space for the repair shop and returns under their 30 day warranty period, they are more likely to give the matter a higher priority.

---- Steve

 

[stoney]

John,

If the set is only 14 months old, then there is a good chance the picture tube is still under parts warranty. I would take the set back to the repair shop and ask who to contact about the warranty on the picture tube. Tube warranties have been dropping every year, but they are still typically at least 2 years. Ask for the phone number of the manufacturer's area representative. Call this person and politely tell them that you are extremely disappointed in the performance of their product.
If the manufacturer had a bad run of tubes, they will usually replace them for the customer's that complain. Sometimes they will cover parts and labor to make the customer happy. Other times only the parts. Typically, the bench charge for replacing a tube is about 2 hours since numerous adjustments are required. You would have to pay this labor charge, but it should be much cheaper than a new set.
Make sure the repair shop understands that if they can help you get the tube under warranty, then you will pay the install labor. Otherwise, they really do not have a big incentive to help you.
The reason for taking the set back immediately is two fold: first, it not really useable to you. Secondly, when it is taking up shelf space for the repair shop and returns under their 30 day warranty period, they are more likely to give the matter a higher priority.

I contacted the technician again today and he said the problem I was having each time occurred briefly yesterday again (at least while in the repair shop again this time) so he did a test and his equipment indicated there's no short to the cathode so clearly the original repair was not the problem - right?(I am confused) and he now says it's definately not a short to the blue gun but something outside the picture tube.He replaced a couple of resistors at the bottom (whatever that means) and it's running fine but he wants to continue testing it. It seems to me it's guess work on his part and i have no tv still I said at this rate his warranty would be running out, it's now 13 days into the arranty but he said not to worry about that as all his work is guaranteed.Not exactly sure what that means.
He also said yesterday he'd contacted the manufacturer via fax but as of y/day had not received a reply When I asked when i was gonna get it back he said as soon as he had a definate awnser - doesn't exactly help me much.
But now he says it's definately not related to the tube so it would seem that it doesn't need replacing even if as you suggest the manufacturer's would do the right thing by me seeings how the set is so new. I will keep you updated.At least on here there's no smart ass comments like on the google elecrics groups.
Thanks
john
ps if you need a scan of original repair warranty I can scan and attach it next time,but I sort of covered it all in my previous post. Very dissapointed by all this.

---- Steve

 

[banjo]

John,

Given the symptoms, the problem is a DC bias issue. It could be internal to the tube or external. Externally, this signal is handled as a dc-coupled signal typically from the video output IC to the picture tube. If we assume that the video output IC is OK since the other two colors are fine, then this leaves the tube and the driver transistors and components in the blue gun circuit. The transistors can be eliminated by either replacement or substitution. The identical pairs of transistors are in the red and green circuits. If the technician swaps the transistors and the problem moves to another color, then the transistors are intermittent and the repair is straightforward.

If he is offering a 30 day warranty, that time period should start after the repair is finally complete, not from the initial request for service. However, it is up to lawyers to interpret the real legal meaning of his warranty statements.

My first question now is this repair shop authorized to do warranty repairs on this brand? Check with the manufacturer, usually they have a listing on their web site about what shops are warranty stations in your area. Perhaps he is not authorized to replace the tube under warranty and is therefore not willing to consider it the culprit. I would still contact the manufacturer about your problem, explain the symptoms and if they are having picture tube problems, they should be pretty helpful. If the current shop is not the authorized warranty repair station, call the repair shop that is authorized and get their opinion. The authorized shop will see the biggest volume of these sets. Therefore, they will know if tubes are going out. Also, authorized shops would receive any service bulletins notifying them of any field upgrades or fixes for recurring problems.

You may have to take your losses, pull the set out of this shop, and take it to another one. Changing a picture tube is a fairly big job for a TV shop. With the prices of TVs constantly dropping, the new shops probably don't change as many tubes as we used to do in the old days. (I am an engineer now, having left the TV business 15 years ago.) Perhaps he is not willing to tackle this size of job.

Regardless, call the manufacturer. If their full warranty was 1 year, then you are only just a couple of months past that. It is unreasonable that a TV less than 2 years old is unrepairable! Keep asking the manufacturer who can repair it and who else in their company you can talk to about the problem.

--- Steve

 

[stoney]

John,

Given the symptoms, the problem is a DC bias issue. It could be internal to the tube or external. Externally, this signal is handled as a dc-coupled signal typically from the video output IC to the picture tube. If we assume that the video output IC is OK since the other two colors are fine, then this leaves the tube and the driver transistors and components in the blue gun circuit. The transistors can be eliminated by either replacement or substitution. The identical pairs of transistors are in the red and green circuits. If the technician swaps the transistors and the problem moves to another color, then the transistors are intermittent and the repair is straightforward.

If he is offering a 30 day warranty, that time period should start after the repair is finally complete, not from the initial request for service. However, it is up to lawyers to interpret the real legal meaning of his warranty statements.

My first question now is this repair shop authorized to do warranty repairs on this brand? Check with the manufacturer, usually they have a listing on their web site about what shops are warranty stations in your area. Perhaps he is not authorized to replace the tube under warranty and is therefore not willing to consider it the culprit. I would still contact the manufacturer about your problem, explain the symptoms and if they are having picture tube problems, they should be pretty helpful. If the current shop is not the authorized warranty repair station, call the repair shop that is authorized and get their opinion. The authorized shop will see the biggest volume of these sets. Therefore, they will know if tubes are going out. Also, authorized shops would receive any service bulletins notifying them of any field upgrades or fixes for recurring problems.

You may have to take your losses, pull the set out of this shop, and take it to another one. Changing a picture tube is a fairly big job for a TV shop. With the prices of TVs constantly dropping, the new shops probably don't change as many tubes as we used to do in the old days. (I am an engineer now, having left the TV business 15 years ago.) Perhaps he is not willing to tackle this size of job.

Regardless, call the manufacturer. If their full warranty was 1 year, then you are only just a couple of months past that. It is unreasonable that a TV less than 2 years old is unrepairable! Keep asking the manufacturer who can repair it and who else in their company you can talk to about the problem.

--- Steve

Hi,
according to thier yellow pages ad they do repairs to all makes and models and when i first contacted them they did ask what brand so am now assuming from your post that they are ''allowed'' to do repairs on this brand.
Yes I know some brands/companies have certain outlets for thier models,there's only 1 listed for AWA tv's in my area but it's not easily accessible which is why I contacted who I did.
When I first contacted AWA by phone and email via thier website they just informed me ''we don't do repairs on tv's'' and to contact place i bought it from and they'd tell me - how useless is that?! A lot of different brands don't even have ''official'' repairers in my area (and i don't live out in the sticks!) - and i'm in the capital city for god sakes!
Well that's good on the warranty thing that it starts from when job is finally finsihed. Just wish it was,it's been 2 weeks now. I think worse case scenario is if when i get it back it goes again I will either have to take it elsewhere or buy a new one!
Techo said it's been working fine in the shop (though got the recurring fault again other day - see my last post, so he replaced a couple of resistors) and hes had it running virtually all the time the store's been open. I wonder if that's a good thing?But then surely if I wanted to I could have the tv running several hours a day every day and it shouldn't be a problem.
Obviously the fixes he did initially weren't the cause of the problem,just hope that now he's replaced a couple more resistors i'm not gonna be charged more $$$

I think he's holding on to it for so long to make sure nothing else goes wrong causing the problem while he's got it? Thing is though, as they say, how long's a piece of string?!
Techo did say he contacted the manufaturer couple of days ago by fax for more info but at that time he'd not head back from them and he didn't mention it when I called yesterday,so either still hasn't had a reply or I'm getting the run around.Must admit the techo does seem honest though. Unless his constant ''frustration'' comment is a facade. Do you have access to a manual for this particular model? I can't find one listed online anywhere. As you say a new tv should last more than 14 months. I get the impression the techo doesn't like me to make suggestions as to the problem/cause and what he should try. Sort of like,i'm the techo and i'm having problems,so how would you know type of thing. I just want it fixed and returned. Maybe the longer he has it is a good thing,so he can cover all options?! Hard to judge.
Strange not much info on AWA tv's online yet its a brand that's been around for years (I think mostly imported now though) and i've always liked AWA never had any problems,so it's why i've stuck with them.
Thanks for reply,I will keep you updated - it seems AWA don't seem to care,like most big companies all thier interested in is the $$ profit!
John

 

[stoney]

Re: AWA TV model W571 blue screen with white stripes UPDATE

Hi,
an update - cause FINALLY found!
Techo rang this arvo and said cause had finally be found.I'll try and explain it as best I can remember.
There is a pin inside a socket attached to the blue gun which was becoming ''grounded'' and thus swamping all the other colours with blue,hence my problem.
Now this supposedly isn't as common as most think (typical,never anything easy!)and requires a spare part which has to be ordered from interstate - typical again!So in the meantime he's washed this socket with some kind of solution to prevent the pin from Grounding and once the pin arrives from manufacturers he will replace it. In the meantime am getting the set back and techo said he would call me when the part arrives and will pick up set again and replace the part. So we're on track now - AT LEAST!