Sony 40'' will not turn on "Unless"

ehelp · Joined: 05 Nov 2007 Posts: 3

I have a Sony 40XBR800 and starting a few weeks ago, the tv would not go on unless I blew "hot air" with my hair drier onto the D board.

What can be causing this and why does it go on when I heat it up? It usually only takes about 30 seconds with the hot air and then it runs good all day long.

Any suggestions would be greatly appreciated.

Graeme · Joined: 05 Nov 2007 Posts: 10

What is a D board?
PSU?

I suspect dry joints. I also suspect faulty joins within a heat-generating component, such as a regulator or pass transistor.

The fact that it only goes when heated, then keeps going is a symptom I have seen before in my service career.

Faulty CRT guns can sometimes cause this symptom - generally Philips flat-screen sets from about 5 years ago.

Manufacturing faults in the way the connections are spot-welded to the electron-gun connections result in the set not working when cold, but if you heat the end of the CRT yolk with a hot-air gun, you cause the crook spot-welded connections to expand, and make contact.

I digress...

Sometimes you can heat a transistor or regulator, and it will spring to life.
Provided that there is a reasonable load on the device, it will dissipate heat, and this heat due to load can be enough to keep the device working, but let it get cold, and the faulty connection(s) contract, and break the circuit, therefore the device fails to start when it is next asked to.

This is easily fixed by replacing the faulty part.

I would be looking very carefully on this board of yours, for dry joints, and would probably start replacing any devices mounted to any heatsinking.

Good luck.

G.

minnie · Joined: 18 Aug 2005 Posts: 2511 Location: Hell

How many times does the red light blink?

cory · Guest

replace the ic close to the flyback.16 or 18 pins for high voltage startup.---3001.

minnie · Joined: 18 Aug 2005 Posts: 2511 Location: Hell

The easy button is send the D board to Sony for phase 3 repair but Cory is also correct. Last board I sent in, that IC was replaced.

Frank · Guest

replace the ic close to the flyback.16 or 18 pins for high voltage startup.---3001.

Cory you mean IC 6501When you say 3001=MZ3001?

ehelp · Joined: 05 Nov 2007 Posts: 3

Thank you for the quick responses, I did suspect that it was a bad IC but I am weary in removing the board as I would need to discharge the crt.

The stand-by light blinks six times when off and seven whnen it tries to go on.

I think it will be wiser to buy a new set ... and scrap this one.

Frank · Guest

LOW +B OCP/OVP
(overcurrent/overvoltage)***
6 times 6:0 or 6:1 • +5 line is overloaded. (A, B, M Boards)
• +5 line is shorted. (A, B, M Boards)
• IC504 is faulty. (A Board)
• No picture
Horizontal Deflection
Stopped
7 times 7:0 or 7:1 • No picture,IC6501,IC 8002,C6532, T8005, (D board)

ehelp · Joined: 05 Nov 2007 Posts: 3

Again thanks .... Is there any way that I can get a schematic of this tv .. I have no idea were these IC are located ...

I did poke around the D board and moved a few of the capasitors and litle gizmos and the tv came on without having to heat it up ...

What is a cold solder connectionn and can this also cause my problem?

cory · Guest

yes mz3001.careful if it is soldered on both sides on board.if not a breeze to change.