Dove right in! Help with RCA 21-D-8628

I pulled the chassis and I am looking/checking the caps and resistors. Let's see what happens in a bit

C515 is 2kv .001- this is original, fixed ceramic.

The blue/grn lead above the ceramic cap is from the vertical transformer, I can't which cap/res is in combo with it.

As to the dag and chassis ground, you can see the wire/springs/and chassis ground (bottom left)

[Kevin Kuehn]

Does your RCA service info have a pictorial of what capacitor values are located where on the circuit boards?

[Kevin Kuehn]

Originally Posted by BandDirector

As to the dag and chassis ground, you can see the wire/springs/and chassis ground (bottom left)

That all looks good. Automatically grounds when you mount the chassis.

Originally Posted by Kevin Kuehn

Does your RCA service info have a pictorial of what capacitor values are located where on the circuit boards?

Nope, just the modules with component numbers, refer back to schematic, then component index list. It has been a challenge to just stay in the same place on the map so to speak.

3 caps aren't giving me immediate readings, I should probably replace them or clean the leads.

[Kevin Kuehn]

If you're trying to measure them connected in circuit that doesn't always work. For starters just verify the values marked on the cap match the component list/schematic value. And sometimes you just need walk away and come back when you're refreshed and more able to focus.

[Kevin Kuehn]

Is the lead my yellow arrow is pointing to really soldered?

Yes. Added a bit more.

I replaced a few new caps, added a slightly higher mf cap on vertical, and reinforced the solder lines connecting the little board that is perpendicular to the main vertical board. For a hot minute or two I had a stable, non-flickering image. But it wasn't in any way centered via vert/horiz.

Here is another pic. This didn't last long when I tried to adjust it

[Kevin Kuehn]

Looking better. I only see one picture now, and primarily a linearity issue. It's possible the vertical hold, height, and/or linearity pot's are flaky. They could be open, dirty, or drifted high in value. A scope could come in real handy now to look at the vertical waveform on the grid of the vertical output tube.

[Electronic M]

Which cap did you change capacitance on and did you measure and replace off tolerance resistors yet?

Paper/film caps should not deviate from the original design values (except in cases where the original is an NLA value like .05 and you have to use the closest modern value, in my example .047).

Before you try the absolute desperation move of changing film cap values you need to measure the resistance of every resistor in the vertical circuit (Google "resistor color code" explanation of how to read value) and change resistors outside of tolerance. Tolerance is the 4th band and will be %20 for no band, %10 for silver, and %5 for gold. So for a 100 ohm %10 resistor it is bad if it measures above 110 or under 90.... carbon comp resistors almost never measure lower resistance than their labeled value let alone be out of tolerance on the bottom end....so replace every resistor on the vertical board that measures above and outside of its tolerance rating. The ones below I sometimes ignore because I know they are usually in parallel with another part in circuit (which fools the meter*), but sometimes I'll unhook one lead and measure those again when I'm being thorough.

*2 equal Resistors in parallel form a single resistor of half the value... Resistors of unequal value form a new value equal to (R1 X R2)/(R1+R2)....there are formulas for more than 2 in parallel if you Google.
Resistors in series act like a single resistor with resistane that is the sum of all the resistors in series...these maths also apply to capacitors but parallel caps are the sum and series caps divide (ie it's backwards from resistors).

Always make sure all parts are good before deviating from the original design.

[Kevin Kuehn]

If you can locate them, I would ever so slightly turn the sync stabilizer and AGC pots back and forth from their current position, just enough to see if that has any influence on picture stabilization.