Whining sound, a little smoke and no operation?


  #1  
Old 07-21-01, 09:00 AM
Guest
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Question

I have a faulty Amstrad 14" TV and before I bin it, I just wanted to know if it might be possible to diagnose and repair the fault.

Model No: CTV 1400T

When the unit is powered up there is a high-pitched whining sound coming from some of the components on the main PCB and occasionally there is even a waft of smoke and a slight burning smell. I don't know what these components are called, but it looks like a large coil and heat sink. Although the "standby" LED illuminates when powered up, the unit does not respond to remote control or front panel operation.

I have checked the socket, plug and the one fuse I can see on the main board, but they were all fine There is no obvious spillage or damage either.

Any ideas for diagnosis and repair?
 
  #2  
Old 07-21-01, 05:49 PM
bigmike
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Well Smokey is the TV expert but the secret smoke was let out and that ain't good! I wouldn't leave it pluged in for sure! In my oppinion it's not worth repair,
1.) Because of it's brand.
2.) Anything that smokes like you describe is NOT good! Let Smokey throw his word in before you bin it.
 
  #3  
Old 07-22-01, 08:30 AM
Smokey
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Good Morning, Big Mike/Marco:

Sorry for not responding sooner. Had air conditioning problems and didn't want to cook the computer.

I, too, am not familiar with the brand name so must assume if is "off shore" equipment. In the case of the problem described, it sounds like a short in the high voltage circuit and is most likely a quadrupler module shorted out. The high pitched whine is the horizontal oscillator trying to start and run. The smoke is from an overheated horizontal driver.

This sounds like a lot of expense to repair. Depending on the age of the set, the decision to repair or replace lies with the customer. It is a good idea to get some estimates for repair to fortify the decision.

Smokey
 
  #4  
Old 07-22-01, 10:44 AM
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Many thanks for your help guys It's great getting advice from an expert that you know isn't going to be motivated by profit I will probably just bin it then.

BTW, is there any way to degauss a TV screen? It's an old 21" Hitachi set and there are two strips of discoloration several inches wide at each side. I initially tried power on/off cycles of 30min, 1h etc. and when that didnít work I tried a tiny (very low powered) magnet to manually do it, but it will not clear it. There was a slight problem, but it got noticeably worse after moving the set and returning it to the same spot. There are no speakers or anything else near it that could cause interference.
 
  #5  
Old 07-22-01, 11:13 AM
bigmike
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Cool archives

Hey Marco, Search the archives. This is something that has been covered a few times and I can give my fingers a break.Not hard to do but lengthy to explain...
 
  #6  
Old 07-22-01, 12:27 PM
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Will do Thanks again.
 
  #7  
Old 07-23-01, 03:23 PM
Smokey
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Good evening, Marco:

Yes, this had been addressed before but will address it again for your benefit:

1) Get a pistol action soldering iron (like a Weller unit) that has the capacity of quick action soldering. The interior of this unit is a coil of wire that is several feet in length. When the pistol gun is activated, the coils of wire have a definite magnetic field around them that rises and falls 120 times a second.
If the picture tube is magnetized and displaying colored areas, perhaps the television set's internal demagetizer system is inoperative. This method will work as long as the set is not moved. It it is moved, the picture tube crosses the planes of the earth's magnetic field and becomes magetizied again.

2) Put the pistol soldering gun against the screen of the picture tube and turn it on. Rotate the gun around the screen in a circular motion. As the tip of the gun heats up, move the soldering iron in a circular motion away from the picture tube. When you are 3-4 feet away, turn it off to let it cool.

3) Repeat this process as many times as it takes to remove the residual magnetism in the screen of the picture tube.

Theory: A rapidly changing magnetic field from the gun will destroy the polarity of a fixed magnetism in the screen of the TV.

Smokey says: this works! I used it for years and came away happy.

Smokey
 
 

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