On Wednesday, 10 Sep 2003 09:34:32 -500, "Asimov"
wrote:

"Jason D." bravely wrote to "All" (10 Sep 03 03:48:33)
--- on the heady topic of "Big battle with WEIRD vertical deflection problem in =
PTK195 chassis."

If there are spikes in the output ramp then it would seem like a supply
filter electro problem to me. Have you checked what the supply noise
looks like on the scope? If not then the pump up might be off value.


In RCA's PTK195 (based on CTC195) projector still under warrenty:

Came in with blown vertical IC and crispy 26V supply resistor changed
both and saw noisy waveforms.

Changed pump cap, no difference, finally found the 1.5 ohm 2W is open.
This resistor is connected to .22nF 100V to ground from the output of
TDA8172 vertical IC. Changed both cap and resistor. Got perfect
vertical waveforms. Now I have a cooked vertical IC after a minute.
Now I know why: one of yoke is bad.

RCA using this vertical IC TDA9302 and TDA8172 very rarely blow so if
you see one with blown one, be suspicious because this is when
something is killing that vertical IC. A half-dried pump cap doesn't
faze vertical IC, customer complaint with squished top pix got that
fixed instead. Usually often is tuner & micro grounds if the pump cap
isn't the problem.

Back to this damned projector, how can I tell which yoke is guilty?

Cheers,

Wizard