Track: Lame must live !!!
Author: Macros/Kotlas town. Fressshhh...
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Hello to all TV masters!
Just recently they brought it to me for repair.
TV box - "Dawn", it seems, it's called.
Nope, not tube... On transistors.
Well then. You plug it into the network - and from
there's smoke coming from it. Kotsoft joked - more
put a fan and there will be smoke
car :)
There is nothing to do - it needs to be repaired.
In short, through the rezuk, which was burning,
the power supply supplied a voltage of 96 volts
for a fee. It is clear that the rezuk burned due to
overload in the circuit after it. Just for now
I understood this, the rezuk finally died.
I started searching according to the scheme... Which one
scheme? I didn’t have a diagram from him. I
I used the scheme from "Rekord"
third generation, as it turned out
that they coincide by almost 90% ;)
In short, 96 V after this summary goes to
line, and after it - to the transistor
KT838 (so big, on the radiator). B
the base circuit of this transistor is turned on
secondary winding of the isolator
transformer, and the primary - on
emitter circuit of another transistor, to
the base of which is supplied lowercase
sync pulse. In short, in the end
line windingmust arise
oscillations, and the remaining windings
used to create secondary
supply voltages: for the kinescope filament,
to the second anode, somewhere else...
Well, that's it. The transistor turned out to be
serviceable, and there is more short to ground there
nothing could. During the experiments
new shortcut, which I put in place of
old, rather charred...
There is nothing to do - you have to unsolder
load from the remaining line windings.
I unsoldered one - it still smokes, the second,
the third... I unsoldered everything. I turn it on - it doesn't smoke
less!
How is this so, because I checked the line -
there are no breaks, short circuits, it seems,
too...
But neither theoretically nor
practically nothing could create
overload in the circuit.
Then I got to my TV and
The liner fell out of it. I bet on that one
TV box - everything works, and nothing
smokes! Hehe...
It turns out that in that native line
there were short-circuited turns, which is why
an overload was created.
In general, the presence of short-circuited turns
can be checked in any transformer
using an oscilloscope. Collecting
LC circuit, connect the generator and
look.
Well, let's take things in order. This check
based on the phenomenon of parallel
resonance. Increasing the amplitude of oscillations
on the low-frequency generator two or more times
indicates that the frequency of the external
generator corresponds to frequency
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