Can tv chassis be powered without defl. coils.

[Russell Griffiths]

Greetings group.
As a lot of you would know, it is often difficult to
work on a ctv chassis when it is still connected to the
rest of the set.

Would it be bad to turn the chassis on fully without
the deflection coils connected?

Could the HOT or maybe power supply parts be damaged?

Thanks,
Russell.

 

[Craig Hart]

Every design will behave differently, HOWEVER the usual result is fried
vertical deflection controller IC, fried FBT driver transistor, and assorted
incidental parts damaged.

In other words, don't do it. Years ago you could buy extender leads to get
around this probem - these days I just made some dets up myself from scrap
parts.


"Russell Griffiths" <rg26ce1991@hotmail.com> wrote in message
news:13cdb672.0401200402.4064bc5f@posting.google.com...

Greetings group.
As a lot of you would know, it is often difficult to
work on a ctv chassis when it is still connected to the
rest of the set.

Would it be bad to turn the chassis on fully without
the deflection coils connected?

Could the HOT or maybe power supply parts be damaged?

Thanks,
Russell.

 

[amstereo]

my guess is, without a deflection coil, youd get full intensity of the gun
fired straight at the center of the screen, which, would very quickly burn a
perminent spot right there. similar to old sets that shrank to a center dot
on turn off.

 

[KLR]

On 20 Jan 2004 04:02:10 -0800, rg26ce1991@hotmail.com (Russell
Griffiths) wrote:

Greetings group.
As a lot of you would know, it is often difficult to
work on a ctv chassis when it is still connected to the
rest of the set.

Would it be bad to turn the chassis on fully without
the deflection coils connected?

Could the HOT or maybe power supply parts be damaged?

Thanks,
Russell.

I'n some maybe - but I wouldnt be going round doing it as standard
practice. The Horizontal yoke forms part of the tuned circuit for the
horizontal output. Even if it doesnt work - this may alter the
circuit enough to cause inaccurate voltages etc to occur in other
parts of the circuit - or in rails powered from the secondary of the
EHT transformer

I have done it a few times by accident with no damage resulting
though.

in many older sets - the yoke plug had a link on it that would cut the
B+ supply to the horizontal output stage if the yoke plug was pulled
This to me meant that it wasnt safe to run the thing without a yoke
and it was a safety measure to prevent damage. This wouldnt have been
done for no good reason

Make extension leads, most sets Ive seen over the years (except some
euro ones) have the same type of 4 way plug and socket assembly. You
could get an old set from a rubbish tip sale, salvage these and make
up a neat little extension cable with them. There can be a high
voltage on the horizontal coil (several hundred volts) - so used
suitably rated wire and properly insulate any joins you might make in
it..