"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.


JD From: (Jason D.)

JD Quickie on the type of vertical circuit:
JD For others who isn't famillar with this PTK195 as well as CTC197
JD chassis, this vertical circuit is virtually same in CTC17x, 18x, 203
JD and up using TDA8172 vertical IC.

JD This set came in with blown vertical IC and a very crispy 1 ohm 2W
JD resistor (snapped in two when I took it out) for 26V supply to the
JD vertical only. Fixed that up. Gee that's a FIRST for me to actually
JD have to replace that in RCA in my 1 and half years for a shop.

JD Well! This one really got me stumped, top most is bowed in,
JD non-linear lines and all shaking like mad while most of pix is
JD perfect. Got all my tools on that (scope, dmm and ESR meter) All the
JD 26V and 13V supplies are quiet and smooth, caps checks good EXCEPT: on
JD scope on output of vertical IC I see this like this:

JD Retrace pulse as it should be, then a normal clean ramp down to appox
JD mid way then I see high frequency noise centered around that ramp down
JD to the bottom just before the retrace pulse I see few sharp tall thin
JD spikes. Reminds me like this imagine chroma waveform without steps
JD with half top the pix b/w and half bottom in color.

JD Even I subbed a good yoke on each of R, G, G yoke connectors in turn
JD with no luck hoping to catch a bad yoke.

JD When this that JURG6006's came up with this vertical IC problem on
JD "Subject: Mit. VS5010 intermittent shutdown" my attention snapped up
JD and had to post mine too.

JD That vertical noise is confusing the top convergence area so bad that
JD top part is jumping around: straight and bowed irratically.

JD BTW: I tried another RN14501 with no luck, the sawtooth input is
JD clean at that RN14501.

JD Cheers,

JD Wizard

.... Resistance Is Futile! (If 1 ohm)