Philips 21CE1251 TV repair/disassembly problem

[Overdoc]

Hello,

I am new to this group but it seems there are lots of knowledgeable people
here, so I hope someone can help me to disassmble my old Philips TV.

The TV has started to have a problem that the screen slowly goes dark after
warmup, while the sound stays on.
After some testing with freeze-spray I discovered that when I gently push
the line-transformer ( flyback )with a rubber stick, then the picture will
come up bright again. ( I know about the high voltage risk so I did wear a
glove and kept the other hand in my pocket to be sure )
Now, I think there must be a cold solder joint on the line transformer and I
want to resolder all connections. Looks logically to me, since the line
transformer is probably one of the heaviest parts on the board, so it can
easily become loose when the TV is carried around much ( which has been the
case )

Ok, but now I discoverd the board cannot be pulled out that easily
There is some plastic chassis which has some 'fingers' that hold on the
wooden bottom of the TV's case. The PCB is just stuck inside this plastic
chassis and doesn't want to move.
I found out there are 2 snappers in the chassis, but even if I pull both of
them to the side the PCB wouldn't come out

I hope most Philips TVs are more or less equal in design, and so someone
might know how to pull the PCB out of the chassis a little so I can reach
the line-transformer's pins with my soldering iron ?
The exact type of the TV is: Phiips 21CE1251, and it is probably more than
15 years old.

If anyone could help me and give me some hint I would be very grateful !

Thanks a lot in advance,

Reini

 

[Alain Beguin]

*Overdoc* a écrit/schreef/wrote le/op/on 14/01/2004

Now, I think there must be a cold solder joint on the line transformer and I
want to resolder all connections.

That is correct and you should do that, indeed.

I found out there are 2 snappers in the chassis, but even if I pull both of
them to the side the PCB wouldn't come out

It should, you have to maintain those two snap outwards and pull the
chassis out to the rear, of course
The chassis must come out, like that. Then pull out all plugs and
remove the chassis out.
This is usually very easy to perform.

When reassembling...do *not* forget to connect the ground wire on the
picture tube to the tube socket print, otherwise you could destroy the
processor.

The exact type of the TV is: Phiips 21CE1251, and it is probably more than
15 years old.

The chassis name is "CP90"

If anyone could help me and give me some hint I would be very grateful !

OK Try again!

Thanks a lot in advance,

No thanks and let us know.


Alain

--
*Alain Beguin*
mailto: http://cerbermail.com/?XiEiqwImaa
Newsreader: _/MesNews/_ http://mesnews.no-ip.com

 

[GPG]

"Overdoc" <sodan@europe.com> wrote in message news:<XWgNb.128382$Tz1.1736@news.chello.at>...

Hello,

I am new to this group but it seems there are lots of knowledgeable people
here, so I hope someone can help me to disassmble my old Philips TV.

The TV has started to have a problem that the screen slowly goes dark after
warmup, while the sound stays on.
After some testing with freeze-spray I discovered that when I gently push
the line-transformer ( flyback )with a rubber stick, then the picture will
come up bright again. ( I know about the high voltage risk so I did wear a
glove and kept the other hand in my pocket to be sure )
Now, I think there must be a cold solder joint on the line transformer and I
want to resolder all connections. Looks logically to me, since the line
transformer is probably one of the heaviest parts on the board, so it can
easily become loose when the TV is carried around much ( which has been the
case )

Ok, but now I discoverd the board cannot be pulled out that easily
There is some plastic chassis which has some 'fingers' that hold on the
wooden bottom of the TV's case. The PCB is just stuck inside this plastic
chassis and doesn't want to move.
I found out there are 2 snappers in the chassis, but even if I pull both of
them to the side the PCB wouldn't come out

I hope most Philips TVs are more or less equal in design, and so someone
might know how to pull the PCB out of the chassis a little so I can reach
the line-transformer's pins with my soldering iron ?
The exact type of the TV is: Phiips 21CE1251, and it is probably more than
15 years old.

If anyone could help me and give me some hint I would be very grateful !

Thanks a lot in advance,

Reini

There are 4 screws to be removed. Board will then slide so fingers on
carrier match slots in pcb.

 

[GPG]

peg@slingshot.co.nz (GPG) wrote in message news:<62069f15.0401141743.5216539a@posting.google.com>...

"Overdoc" <sodan@europe.com> wrote in message news:<XWgNb.128382$Tz1.1736@news.chello.at>...
Hello,

I am new to this group but it seems there are lots of knowledgeable people
here, so I hope someone can help me to disassmble my old Philips TV.

The TV has started to have a problem that the screen slowly goes dark after
warmup, while the sound stays on.
After some testing with freeze-spray I discovered that when I gently push
the line-transformer ( flyback )with a rubber stick, then the picture will
come up bright again. ( I know about the high voltage risk so I did wear a
glove and kept the other hand in my pocket to be sure )
Now, I think there must be a cold solder joint on the line transformer and I
want to resolder all connections. Looks logically to me, since the line
transformer is probably one of the heaviest parts on the board, so it can
easily become loose when the TV is carried around much ( which has been the
case )

Ok, but now I discoverd the board cannot be pulled out that easily
There is some plastic chassis which has some 'fingers' that hold on the
wooden bottom of the TV's case. The PCB is just stuck inside this plastic
chassis and doesn't want to move.
I found out there are 2 snappers in the chassis, but even if I pull both of
them to the side the PCB wouldn't come out

I hope most Philips TVs are more or less equal in design, and so someone
might know how to pull the PCB out of the chassis a little so I can reach
the line-transformer's pins with my soldering iron ?
The exact type of the TV is: Phiips 21CE1251, and it is probably more than
15 years old.

If anyone could help me and give me some hint I would be very grateful !

Thanks a lot in advance,

Reini

There are 4 screws to be removed. Board will then slide so fingers on
carrier match slots in pcb. When c

To remove the carrier from the tv lift both clips and slide the carrier back.
To remove completely hold the clips up
To remove board from carrier see previous

Not all bad joints are obvious, and they are common.

 

[Overdoc]

Alain Beguin schrieb in Nachricht ...

It should, you have to maintain those two snap outwards and pull the
chassis out to the rear, of course
The chassis must come out, like that. Then pull out all plugs and
remove the chassis out.
This is usually very easy to perform.

Hmm, I tried as you say and pulled both snaps outwards and tried to pull the
board out of the chassis, but it doesn't want to come out, not even when I
pull very strongly !
And, also the chassis doesn't move....

Seems like I should leave this thing alone - maybe I am too stupid or what,
although I have repaired my microwave, warmwater/heating machine, washing
machine, dozens of homecomputers and also an old Commodore monitor ( also
had bad solder joint on flyback ) and other electronic equipment. Never had
a problem disassembing something ( and I also always was able to reassemble
it )

When reassembling...do *not* forget to connect the ground wire on the
picture tube to the tube socket print, otherwise you could destroy the
processor.

No problem as I always mark every cable and such with a small paper so I
know where it has to be connected afterwards

No thanks and let us know.

Do you have any other ideas what I might doing wrong ?
Do I have to remove the power on/off switch from the outside first, or
something like this ?

Nice greetings from Austria,
Reini

 

[Alain Beguin]

*Overdoc* a écrit/schreef/wrote le/op/on 15/01/2004

Do you have any other ideas what I might doing wrong ?
Do I have to remove the power on/off switch from the outside first, or
something like this ?

Hello again,

I never had that problem, so I'm affraid I can't tell you more.
Look carefully if there is a screw somewhere in the front behind a
small door with buttons behind.
If that is the case, sorry then but I don't remember seeing that.

Otherwise, maybe best to try and find a service doc?

Alain

--
*Alain Beguin* Hello from Belgium
mailto: http://cerbermail.com/?XiEiqwImaa
Newsreader: _/MesNews/_ http://mesnews.no-ip.com

 

[Overdoc]

Alain Beguin schrieb in Nachricht ...

I never had that problem, so I'm affraid I can't tell you more.
Look carefully if there is a screw somewhere in the front behind a
small door with buttons behind.
If that is the case, sorry then but I don't remember seeing that.

Woohoo !!
I made it now Must have got stuck or something during those 15 years,
because suddenly I could pull it out quite easily.

Have resoldered the flyback and the TV now has been running for an hour or
so, and has stayed up bright since
Hope it is ok again.
Nevertheless I will get some new elkos because especially one of them ( the
biggest one ) seems to have dryed out. It has some deformation and isn't
really cylindrical any more. I am afraid such dryed out elkos could kill the
flyback, which would mean death to the TV

Otherwise, maybe best to try and find a service doc?

Never, that by far wouldn't be worth the effort.
I can almost get a new one for the cost of a repair, and a used one much
cheaper !
Unfortunately, nowadays if you cannot repair it yourself, then you can do
nothing except throwing it on the dump

Thanks for your help again !

Reini