Symphonic Flyback
 

I have a Symphonic TV model #WF2702. The set won't power up. When power
button pressed, the flyback makes a ticking sound for a few seconds
then stops. Does this every time power button is pressed. I suspect a
bad flyback. Only reading 42 volts at Hot collector. Removed flyback,
and reading same voltage though. The flyback part # is LTF00CPP1011.
Can't seem to locate it. One more thing, I do have 170 volts raw B+ at
primary of switching transformer.

"Rono" wrote in message
...
Measure the horizontal output transistor!
Ticking doesn't necessarily mean the flyback
is bad! Something is dragging the B+ down!
Rono.




Yeah, flyback failure is pretty rare, and if it is bad scrap the set, a
Symphonic just isn't worth spending a lot of time or money on.

you could try powering up the set slowly with a varic xtrans, keeping
the input ac no more then 60 to 90 volts. the set will not be powered
up full and ya can read all the low voltages to see which one is
loading down. mostly likely the feedback of the start up horz circuit
is failing to hold.

Pathogen wrote:
you could try powering up the set slowly with a varic xtrans, keeping
the input ac no more then 60 to 90 volts. the set will not be powered
up full and ya can read all the low voltages to see which one is
loading down. mostly likely the feedback of the start up horz circuit
is failing to hold.



Ok, I checked the flyback with 2 different Sencore analyzers. The
primary is good. The secondary checks bad. From what I understand, this
flyback is a common fault in this particular peice of s%*t. Anyhow, can
someone tell me if the secondary fails to produce the 24v, 14.5v, etc,
will this prevent the set from powering up? Looking at a schematic with
linear power supply, this is the case. Thanks guys. Sorry, and gals.

The secondary gives out a voltage reference called 'abl' - which is
monitored for proper current. If too high, or not enough, it will shut the
set down to prevent HV damage.


wrote in message
oups.com...
|
| Pathogen wrote:
| you could try powering up the set slowly with a varic xtrans, keeping
| the input ac no more then 60 to 90 volts. the set will not be powered
| up full and ya can read all the low voltages to see which one is
| loading down. mostly likely the feedback of the start up horz circuit
| is failing to hold.
|
|
|
| Ok, I checked the flyback with 2 different Sencore analyzers. The
| primary is good. The secondary checks bad. From what I understand, this
| flyback is a common fault in this particular peice of s%*t. Anyhow, can
| someone tell me if the secondary fails to produce the 24v, 14.5v, etc,
| will this prevent the set from powering up? Looking at a schematic with
| linear power supply, this is the case. Thanks guys. Sorry, and gals.
|