Vert hold/control ? - Page 3 - Videokarma.org TV - Video

Wind157 · #1 05-20-2018, 03:12 PM

That's good info, thanks.

The cap was from mouse and while I saw the plus sign the SAMS nor the can indicated where positive polarity went.

That said the cap still doesn't matter as the problem I was trying to fix with it no longer occurs.

I am assuming the yellow wire coming of the can and leading to the vertical control had a bad solder where it connects to one of the tubes.

Wind157 · #2 05-20-2018, 09:53 PM

I truley have no idea why the picture comes in good now. Smoking a resistor and it works now with keeping the old cap in place? Also the yellow wire running from that can to a tube then to the vertical control doesn't seem to do anything. I have a alligator clipped wire connecting the two yellow wires, after I cut it from the soldered point on the tube, and when I disconnected the clip the picture stayed on.
Not complaining but I don't see how anything I've done fixed the problem with the picture.

Popester · #3 05-20-2018, 11:11 PM

Has the vertical oscillator or vertical output tube yet been subbed with another one to eliminate that as a possible problem yet? You will still need to replace that smoked resistor and I would still replace the cap again. That resistor could be a plate bias or something vital for correct operation. This set will look really nice when you get the problem figured out. The jug is in excellent condition.

Wind157 · #4 05-21-2018, 11:48 AM

The tubes seem fine, I have some NOS I switched out and made no difference. I know I need to replace the resistor now. What I don't understand is why the part of the screen that was not displaying an image before now does so when with the same old capacitor. You can see in the attached that the picture on the left is not reaching the bottom of the screen and the picture on the right is filling the screen.
Those are pre/post smoking the resistor but the old cap is still in place. The only other change is the wire going from the Cap's can to a tube then to the vertical control but unhooking the alligator clipping it back to the tube makes no difference in picture quality.
So I guess I will replace the resistor but I am leaving the old capacitor in place as I am getting a full and good picture with it. Why I didn't before I do not know but I am now at the: if it's not broke, don't fix it, stage with the capacitor

Wind157 · #5 05-27-2018, 11:17 PM

Last question and it probably sounds dumb but it's my luck is pick wrong. When ordering a new cap I want to look for AC caps correct?

Wind157 · #6 06-04-2018, 10:30 PM

When putting a cap in parallel to increase its value, is that just voltage or capacitance too?
Have a paper cap that is .047 with 200 vdc. Can't find a cap that low with a minimum of that voltage. Found one that .05 but not sure if two would cause a problem

Wind157 · #7 06-04-2018, 10:44 PM

Also, wtf is this? Pulled up a few times looking for replacement for paper caps. Do I just solder wires to the silver edges?

old_tv_nut · #8 06-04-2018, 11:19 PM

Quote:

Originally Posted by Wind157

When putting a cap in parallel to increase its value, is that just voltage or capacitance too?
Have a paper cap that is .047 with 200 vdc. Can't find a cap that low with a minimum of that voltage. Found one that .05 but not sure if two would cause a problem

When you put capacitors in parallel, the total capacitance is the sum of the two capacitances. I think you understand that?

The voltage rating of the caps is not changed by putting them in parallel. So, for example, if you are replacing .047uf 200v with two parallel caps (say, two .022 uf) they must both be rated 200 v or more. If they are rated a higher voltage than 200, it doesn't hurt.

Electronic M · #9 06-04-2018, 11:37 PM

Quote:

Originally Posted by Wind157

When putting a cap in parallel to increase its value, is that just voltage or capacitance too?
Have a paper cap that is .047 with 200 vdc. Can't find a cap that low with a minimum of that voltage. Found one that .05 but not sure if two would cause a problem

Capacitance is the ONLY value that adds when capacitors are connected in parallel. The voltage of a parallel capacitor combination is that of the lowest sticker voltage rating of any single cap in the parallel group.

Big space to separate topics:

If you want to combine caps in a way that increases the effective voltage rating then you have to connect capacitors in series...However that only works for a group of caps that all have the same capacitance rating (if not then the voltage will divide unevenly in ways that are a pain to predict). Also if you put capacitors in series the capacitance drops. which can be calculated for any number of individual parts wired in parallel by the formula: Ct=1/[ (1/C1) + (1/C2) + (1/C3) + ...+(1/Cn) ] where Ct is the capacitance of the parallel combo and C1 thru Cn are the individual parts that make up the combo. The ... and Cn mean you can calculate your result for a near infinite number of different caps of different capacitances.

Do NOT buy surface mount capacitors for replacing paper capacitors. Buy ones like these (which I use). https://www.mouser.com/ProductDetail...n1p2vhg7KKs%3d

good luck.

old_tv_nut · #10 05-19-2018, 07:35 PM

In a multiple-section electrolytic can capacitor, all the negative terminals of all the individual sections are connected to the outer can, and the positive terminals are the separate solder lugs that protrude through the bottom cardboard (not any twist lugs that connect the can to the chassis). When replacing one of these sections, you must remove any wire(s) that go(es) to the positive terminal of that section and connect them to the positive terminal of the replacement capacitor. The negative terminal of the replacement then has to be connected to the same place as the multi-section can (usually chassis ground).

Since you didn't realize the polarity is marked +, you had a 50/50 chance of getting it backward, and you should consider the replacement ruined and discard it.

Kevin Kuehn · #11 05-20-2018, 02:37 AM

On modern axial lead caps the negative lead will be connected to the outer metallic case, the positive lead will come out of some insulating material. Never assume the polarity markings on the outside wrapper are correct. I've seen several where the heat shrink cover was installed with the polarity reversed.

Electronic M · #12 05-21-2018, 12:36 PM

Possible the smoked resistor shifted tube bias to counteract the problem. Even if a cap in any given stage is not causing an immediate problem you still need to change the lytics and all tubular caps .001uF and up...They will eventually short and kill something MUCH harder to source.

Wind157 · #13 05-21-2018, 12:55 PM

I assume you think replacing the resistor will cause the vertical linearity problem to start occuring again then?

Electronic M · #14 05-21-2018, 01:05 PM

Quote:

Originally Posted by Wind157

I assume you think replacing the resistor will cause the vertical linearity problem to start occur again then?

It is possible but not guaranteed...Worry about having the parts meet spec before worrying about having it work perfectly...Otherwise, parts that have not been made in 50 years may be the next to smoke (due to bad caps, etc.)...

When I was a broke college student I used to try and get by replacing the minimum number of parts...So I can tell you from experience in most cases leave well enough alone (on old defective/risky parts ) = causing a worse failure in the near future.

Wind157 · #15 05-21-2018, 07:29 PM

Yeah my luck is typically that I break something when fixing it though.
I suppose I should take the meter and check the various caps. It's just replacing the caps in the can, I feel like I'm flying blind without know exactly where to connect the replacement cap. Wish I could just find a replacement can instead of three separate caps.