Repost: HELP: Sony TV relay clicking when changing channels...

[Monica Tran]

Dear All,

Sorry I have to repost. I did not get any help other than someone told me to
buy
a new TV. If I could I would. I am a student.

I need some help repairing my Sony TV #KV27S10. Original problem was no
power. I found problems with the transistors and got some parts from a local
electronics shop to replace all related parts as mentioned on some of the
websites. The following parts have been replaced: Q591 (2SC4927), Q601 and
Q602 (2SC4834), Varistor VDR601, VDR602, VDR603, Fusible resistors R607,
R644.
Then it was working until I tried to change the channels. Now it's just
clicking relay.
I have checked all the parts and they all still seem to be in good working
conditions. I also checked the flyback xformer: #1 (Col), #2 (B+), #3
(200V), #4 (H1), #5 (H2), #6 (-15V), #7 (E), #8 (+15V), #9 (27V), #10 (ABL).
All of these points have resistance.
I don't have a scope but I think I might be able to borrow the scope from my
school if I know what I am looking for. I don't have a schematic. I tried
to resolder these parts as well as the flyback transformer connections. Then
the TV works again. I can power it on and off but as soon as I change the
channel, the relay is back clicking again. So what other component is at
fault? Could anyone help me? I really appreciate. Thanks in advance.

 

[JURB6006]

The relay doesn't run off the flyback. The B+ to it is fed from the standby
supply, and the driver transistor is driven by the main uProcessor, which would
be my first suspect. There would be no reason for a channel change to disturb
the standy supply unless somehow the keyboard is shorted knocking out the +5V
source.

Does it act the same with the remote or only from the front panel of the set ?

JURB

 

[Leonard Caillouet]

I have seen some Sony sets want to shut down or behave strangely only when
an antenna connection is made due to a problem in the +/-15 V supplies in
the FBT secondary. Usually it is the negative supply. Might be related.

Leonard

 

[Jason D.]

The relay doesn't run off the flyback. The B+ to it is fed from the standby
supply, and the driver transistor is driven by the main uProcessor, which would
be my first suspect. There would be no reason for a channel change to disturb
the standy supply unless somehow the keyboard is shorted knocking out the +5V
source.

Does it act the same with the remote or only from the front panel of the set ?

JURB

Watch out for horizontal freq changes where Hout pin on jungle IC
should stay steady at 15.7KHz during channel switching.

I had one happen to me. except JVC made POP! every time from speakers
while channel surfing. Jump "POP!", jump "POP!". This chassis, had
audio and rest of things powered by the flyback. Dropout in H-freq
made power cut out for a instant, causing audio IC to make the "POP!".

Cheers,

Wizard