Recently Acquired 1969 Motorola Color Tube Tv

[Notimetolooz]

Originally Posted by Lain94

Ok that is a relief, and makes things way easier knowing that. Another question though. It it OK to replace an electrolytic cap in the tv with a ceramic cap as long as it has the correct mF as mentioned and same voltage or higher. Or will the ceramic cap bother the tv? For example replacing 10uf 15V electrolytic with a new small ceramic one which is 10uf and has a voltage rating of 50v?

I am asking because I have a ton of ceramic caps laying around and it so happens SOME of them seem to fit the values needed for the lower volt/low uf caps.

Pay attention to the way that capacitance is expressed.
1000 pf (mmf) (uuf) = 1 nf = 0.001 uf (mf).
1000 nf = 1 uf (mf).
Most ceramic caps are less than 1 uf (mf). Even film caps seldom are more than 10 uf (mf) and they are very large in that value.
Mica are commonly in values 1 pf (mmf) (uuf) to 1000 pf (mmf) (uuf).
The reason for the most part for using electrolytic caps is that they are smaller and less expensive that other types for the same capacitance.

[Electronic M]

Originally Posted by Lain94

Ok that is a relief, and makes things way easier knowing that. Another question though. It it OK to replace an electrolytic cap in the tv with a ceramic cap as long as it has the correct mF as mentioned and same voltage or higher. Or will the ceramic cap bother the tv? For example replacing 10uf 15V electrolytic with a new small ceramic one which is 10uf and has a voltage rating of 50v?

I am asking because I have a ton of ceramic caps laying around and it so happens SOME of them seem to fit the values needed for the lower volt/low uf caps.

Based on the values it sounds like the 'ceramic' caps you have ar ceramic encased Tantalum dielectric caps.
I believe modern tantalums will sub fine for lytics, but haven't tried those in tube gear to be sure.
Ceramic dielectric caps are usually disc caps and typically aren't seen in values above 0.1uF. The old school ones that look like 30s era dog bone resistors are typically pF (aka mmf in old speak).

Paper caps shouldn't be replaced by ceramic dielectric caps as ceramics are not temperature stable and exhibit piezo electric dimensional changes in dielectric thickness and thus capacitance as voltage is applied so in some applications where they get high voltage AC waveforms they will pass them in a non-linear fashion.

[old_tv_nut]

Tantalum caps can be useful for their small size, BUT they degrade permanently and fail if they are EVER reverse biased. So, typically used only for bypassing power to ground, not as interstage coupling or waveform generating components, where the voltages on either end can rise at different rates during turn on.

Safest thing in restoring old gear is to replace electrolytics with electrolytics.

[Lain94]

I just pulled this capacitor out of the tv and I am not sure what type it is. It is definitely not an electrolytic. I can not identify it but it resembles the "black beauty" or "black cat" capacitors. Can anyone identify it?

https://imgur.com/a/KWQtDRu

[Notimetolooz]

That is a Motorola brand cap and I don't know whether it is paper of plastic film. It is a molded plastic case.
There were some caps by Sprague that looked similar. The ones with white printing were paper, the ones with red printing were plastic film.
That was a situation that was not very common where it was hard to tell from the general look.
Those could actually be made by Sprague but branded by Motorola, that kind of thing happened many times.
If you have a capacitance leakage tester that tested using hundreds of volts it would tell if the capacitor is good.
I'm pretty sure someone else may know how they are constructed.
I have cut similar caps apart but it can be hard to tell, the paper can be extremely thin and look transparent like plastic. They also can be very tightly wound.
Also from the time the TV is from they could be either one. Sometimes the SAMS parts list states if it is paper or plastic. SAMS also lists electrolytic caps separately.
With out knowing for sure, I would not replace those unless they were suspected to cause a problem.

[Electronic M]

Originally Posted by Notimetolooz

That is a Motorola brand cap and I don't know whether it is paper of plastic film. It is a molded plastic case.
There were some caps by Sprague that looked similar. The ones with white printing were paper, the ones with red printing were plastic film.
That was a situation that was not very common where it was hard to tell from the general look.
Those could actually be made by Sprague but branded by Motorola, that kind of thing happened many times.
If you have a capacitance leakage tester that tested using hundreds of volts it would tell if the capacitor is good.
I'm pretty sure someone else may know how they are constructed.
I have cut similar caps apart but it can be hard to tell, the paper can be extremely thin and look transparent like plastic. They also can be very tightly wound.
Also from the time the TV is from they could be either one. Sometimes the SAMS parts list states if it is paper or plastic. SAMS also lists electrolytic caps separately.
With out knowing for sure, I would not replace those unless they were suspected to cause a problem.

If I couldn't prove it's not paper I'd change it...$0.50 and a minute of soldering is easier than having more things to doubt after a recap when it doesn't work.

[old_tv_nut]

Originally Posted by Electronic M

If I couldn't prove it's not paper I'd change it...$0.50 and a minute of soldering is easier than having more things to doubt after a recap when it doesn't work.

Ditto.

Where was this in the circuit?

[Lain94]

Originally Posted by old_tv_nut

Ditto.

Where was this in the circuit?

The capacitor was physically on the top part of the chassis near the high voltage box. As far as the schematic goes it looks to be in the general area where the vertical output tube is and the other stuff related to the vertical.

[Notimetolooz]

Electronic M has a point. I could go either way with this.
However if you are a newbie to this kind of stuff (and you sound like you are) you may create more problems than solve them.
Not only do you have to get the type, value and voltage rating right but you must not make a mistake connecting to the right points. With electrolytic caps you also get the polarity right. It takes a level of concentration that someone that has done a lot of can take for granted. I have come to this conclusion after helping many newbies.
I would definitely replace the electrolytic caps, those almost always have a metal case even if that is covered with a plastic film or cardboard.
You really should get the service info on the set, that may clear up some facts like the type of capacitors and where they are in the circuit.

[Lain94]

Originally Posted by Notimetolooz

Electronic M has a point. I could go either way with this.
However if you are a newbie to this kind of stuff (and you sound like you are) you may create more problems than solve them.
Not only do you have to get the type, value and voltage rating right but you must not make a mistake connecting to the right points. With electrolytic caps you also get the polarity right. It takes a level of concentration that someone that has done a lot of can take for granted. I have come to this conclusion after helping many newbies.
I would definitely replace the electrolytic caps, those almost always have a metal case even if that is covered with a plastic film or cardboard.
You really should get the service info on the set, that may clear up some facts like the type of capacitors and where they are in the circuit.

Yeah I am going to be very careful and take my time with this recap and repair for sure. I will also check everything over before I attempt to power back on. I am taking photos of everything in the chassis as well after and before each step. I do have the sams photo fact for this tv luckily but it only seems to state if a capacitor is electrolytic or not. The part list makes no disctinction between ceramic, mylar, wax paper ect though.

[old_tv_nut]

Originally Posted by Lain94

The capacitor was physically on the top part of the chassis near the high voltage box. As far as the schematic goes it looks to be in the general area where the vertical output tube is and the other stuff related to the vertical.

I think it would be good to slow down and identify a part in the schematic before you replace it or ask questions. Then you can get better opinions on your options.

[Lain94]

Originally Posted by old_tv_nut

I think it would be good to slow down and identify a part in the schematic before you replace it or ask questions. Then you can get better opinions on your options.

Will do. The biggest concern I have at this point is not the recapping. I am pretty confident in getting that taken care of correctly. I just know that the CRT is very high hour. I don't have the equipment to test it but I can tell its is going to be probably a bit dim, since the color drivers are turned all the way up. Someone mentioned about replacing it with a superior newer RCA picture tube which I am all for doing if it is compatible.

[zeno]

If you are chasing a specific problem you can tack in a cap
of the same value & voltage as a test.
If not leave it be for now.
If you are recapping the set just do a few at a time & recheck as
you go. Its always best to get the PS running first the Hoz/HV
then vert. In other words one stage at a time. Mass recapping
very often leads to a broken set thats MUCH harder to fix.

73 Zeno
LFOD !

[Lain94]

Originally Posted by zeno

If you are chasing a specific problem you can tack in a cap
of the same value & voltage as a test.
If not leave it be for now.
If you are recapping the set just do a few at a time & recheck as
you go. Its always best to get the PS running first the Hoz/HV
then vert. In other words one stage at a time. Mass recapping
very often leads to a broken set thats MUCH harder to fix.

73 Zeno
LFOD !

I 100% agree with this. I will only start with the known bad caps first and go from there if necessary just so things will not get too mixed up. On a side note. What are your thoughts on "picture tube brighteners". I have one that was given to me and it is for 90 degree angle rectangular color picture tubes. It basically uses a small transformer to step up the voltage and increase the brightness on a dim/dark weak crt. Is there any drawback to this? I may use that as a temporary remedy for the CRT until I find a suitable replacement for the high hour crt in the set.

[Notimetolooz]

If you are sure that the problem is the CRT and you think you can find a replacement tube, I suppose as a last resort they are OK.
There have been cases where a previous person put a brightner on because they didn't correct the real problem with the set.
Brightners age the gun cathodes faster than normal so whatever life is left in the CRT is used up fast.
The proper use for them was so that a TV owner could have a brighter image while the repair shop was waiting for a replacement CRT to arrive.
Today replacement CRTs are much harder to find.
Typically on a color tube one gun wears out first making the color balance impossible to achieve. If you say all the drive controls are set near one end it suggests there is another problem that is common to all colors.