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Asimov
 
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Default LA7838 Vertical IC and Mitsubishi CS-3535R

"T o d d P a t t i s t" bravely wrote to "All" (13 Oct 05 16:51:57)
--- on the heady topic of " LA7838 Vertical IC and Mitsubishi CS-3535R"

Todd From: T o d d P a t t i s t
Todd Xref: core-easynews sci.electronics.repair:345193

Todd "Asimov"
Todd wrote:

However, as a replier wrote: ring the "yoke",
not the fbk.


Todd This would require some research on the procedure - no
Todd problem, but sometimes these things require some experience
Todd to correctly interpret.

A ringer is basically a pulse generator the output of which is applied
to the coil to be tested through a relatively high impedance. When
observed on a scope, testing a good inductance, the resulting waveform
should show a number of fading resonnant oscillations. If there is
one or more shorted winding in the inductor this robs the magnetic
field energy and dampens that natural oscillation. So instead of 4 to
6 oscillations there may be only 1 or 1-1/2 and depending how badly
shorted, there may even be none. Shorted turns behave like the
secondary of a transformer and rob power from the self inductance.


Todd I have to admit I'd love to know if the problem
Todd is associated with the yoke or the circuit before the yoke.

Well there's always the pincushion correction circuitry. Could be bad
diodes there. However, pincushion affects the bowing of the sides and
a single kink is more a vertical ramp anomaly. Either the output adds
the kink or the vertical oscillator's ramp generation does.

Did you check if the signal at the ramp pin of the LA7838 is linear?

A*s*i*m*o*v

.... Is reactance then illusory? No, it just appears that way...

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