Question: This small cap across C-E of HOT, split or charco

[Jason D.]

What causes this small cap, usually 470-680pF, 2KV one or several
parallel (like in zenith) also parallel with larger poly cap, across
C-E of HOT. Some of sets had this small blue cap turn into BBQ coal
lump or simply split, fail short or run much warmer, sometimes hot to
discolor the blue coating brown?

Every time I see this, I replace this and set would spring back to
normal, width good, waveforms look good, no ringings, but not always
because that cap is still warm or hot.

I want to be 100% sure to get to bottom of this cap "killer" next time
I come across another one like this.

Thanks & cheers,

Wizard

 

[Sofie]

Jason D.
Usually the thing that breaks down the cap is transient high voltage spikes
due to the nature of the circuitry and other components.... particularly the
inductive nature of the flyback.
Replace it with a high quality 2kv disc cap of the original equipment value.
A normal part of all of this is the energy dissipated as moderate heat in
the cap..... if there is any electrical leakage in the cap it is charcoal
time.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
------------------------

"Jason D." <jpero@sympatico.ca> wrote in message
news:3f8f398b.6086746@news1.on.sympatico.ca...

What causes this small cap, usually 470-680pF, 2KV one or several
parallel (like in zenith) also parallel with larger poly cap, across
C-E of HOT. Some of sets had this small blue cap turn into BBQ coal
lump or simply split, fail short or run much warmer, sometimes hot to
discolor the blue coating brown?

Every time I see this, I replace this and set would spring back to
normal, width good, waveforms look good, no ringings, but not always
because that cap is still warm or hot.

I want to be 100% sure to get to bottom of this cap "killer" next time
I come across another one like this.

Thanks & cheers,

Wizard