Recently Acquired 1969 Motorola Color Tube Tv

[Lain94]

Originally Posted by dieseljeep

According to the pictures furnished, it looks like the original CRT. It's made by Motorola if the label shows an EIA number 185. That CRT wasn't that great!

What would my options be as far as replacing the picture tube go? I am not concerned about whether the replacement picture to would be original for the time period of the tv so as long as it physically fits and is electrically compatible.

The picture tube has a minor cataract and is very high hour so I may end up having it replaced eventually if not now.

[Electronic M]

Originally Posted by Lain94

What would my options be as far as replacing the picture tube go? I am not concerned about whether the replacement picture to would be original for the time period of the tv so as long as it physically fits and is electrically compatible.

The picture tube has a minor cataract and is very high hour so I may end up having it replaced eventually if not now.

NOS is fairly rare but the first places I would check are the early television museum earlytelevision.org, and one of our videokarma members (ohohhodafarted) websites. Besides that the only source is another delta gun color TV the same screen size (also somewhat rare).

CRTs we're meant to be rebuilt not replaced but it's a process that takes highly specialized equipment and skills that died with the CRT TV era.



If you were closer I'd be tempted to trade my working but musty smelling 23" moto for your 21".

[Lain94]

Originally Posted by Electronic M

NOS is fairly rare but the first places I would check are the early television museum earlytelevision.org, and one of our videokarma members (ohohhodafarted) websites. Besides that the only source is another delta gun color TV the same screen size (also somewhat rare).

CRTs we're meant to be rebuilt not replaced but it's a process that takes highly specialized equipment and skills that died with the CRT TV era.



If you were closer I'd be tempted to trade my working but musty smelling 23" moto for your 21".

I was worried that replacements would be rare. I did find an ebay listing for a picture tube that I thought was compatible. It is a 21GFP22. I am a bit skeptical though that it actually works and has no issues as the tube has a sticker on it saying "intermittent short". The seller insisted it works but I am not going to buy it when I have no way of testing it for quite some time.

https://www.ebay.com/itm/35355898043...YAAOSwTyhg4B50

[trinescope]

Where is the anode connector on your tube? The 21GFP22 has it on the side, like the 23EGP22. I suppose if you had to, you could replace the HV anode lead with a longer length to use.the more common CRT types with the anode button at the top. The "22" CRT types, AFAIK, will also fit; that means you could use 22JP22 or 22QP22. I have a TS-918 with the GFP tube, fortunately mine is still very strong and makes a nice picture.

[Lain94]

Originally Posted by trinescope

Where is the anode connector on your tube? The 21GFP22 has it on the side, like the 23EGP22. I suppose if you had to, you could replace the HV anode lead with a longer length to use.the more common CRT types with the anode button at the top. The "22" CRT types, AFAIK, will also fit; that means you could use 22JP22 or 22QP22. I have a TS-918 with the GFP tube, fortunately mine is still very strong and makes a nice picture.

Well the current crt picture tube in the tv which appears to be the original is actually a 21GWP22. However I read somewhere online that a 21GFP22 was compatible as a replacement which was why I was looking at the one I mentioned on ebay. The 21GWP22 picture tube has the anode at the top. I may want to replace the rubber anode cap as well since it is white from oxidation and may be breaking down chemically. I would be willing to pay a reasonable price for a guaranteed working preferably low hour CRT picture tube that would work in my TV. It does not have to be original or time period accurate. As long as it will work!

[trinescope]

If your chassis has the HV cage at the left side (viewed facing the rear of the set) then you could use the GFP tube without any modification since the side anode button will be near the HV cage.

[Lain94]

Originally Posted by trinescope

If your chassis has the HV cage at the left side (viewed facing the rear of the set) then you could use the GFP tube without any modification since the side anode button will be near the HV cage.

I can confirm the HV cage is indeed on the left side of the tv when viewed from the back.

[Lain94]

I have identified the primary point of failure in the tv as an impregnated wax paper cap in the power supply circuit. The capacitor failed open and is located right under the line filter and next to where the line power comes in. I noticed the tv has another with an identical value of .15mf and 400V on the top of the chassis. I will also replace that one as well, as the reliability of wax paper caps is notorious for not being good. Will check over the fuses and the circuit breaker once more as well.

Honestly should have realized this sooner, I did see it but did not realize it was a wax paper cap due to the plastic shell on it.

On the plus side ALL the electrolytics in the tv including the can caps all tested GOOD according to the capacitor wizard, which was a big surprise to me.

[AlanInSitges]

Don't trust that; electrolytics in the power supply and sweep circuits need to be replaced. Same with the paper caps in power supply, sweep, and audio. But for next power up, electrolytics.

[Notimetolooz]

Alan is correct.
I had to look up "Capacitor Wizard". That is an ESR (Effective Series Resistance) tester. ESR is important consideration sometimes in solid state circuits, but not very important in tube circuits.
Tube circuits are effected more by electrical leakage and effective capacitance.
A capacitance leakage tester set to the proper voltage and with one capacitor lead disconnected from the circuit is the proper method.
Once one lead is disconnected you may as well replace the capacitor.
Even modern capacitance meters have there problems, excessive leakage can throw off the reading.

[Lain94]

Originally Posted by Notimetolooz

Alan is correct.
I had to look up "Capacitor Wizard". That is an ESR (Effective Series Resistance) tester. ESR is important consideration sometimes in solid state circuits, but not very important in tube circuits.
Tube circuits are effected more by electrical leakage and effective capacitance.
A capacitance leakage tester set to the proper voltage and with one capacitor lead disconnected from the circuit is the proper method.
Once one lead is disconnected you may as well replace the capacitor.
Even modern capacitance meters have there problems, excessive leakage can throw off the reading.

I did not realize ESR was not as big of a deal in vacuum tube stuff. I kind of figured it was too good to be true that ALL the electrolytics in this tv were somehow not having some issues. The storage conditions of this tv over the most recent 20 years prior to me getting it were not ideal at all, humid hot and sometimes flooded basement. Honestly surprised it managed to turn on at all the first try before that safety wax paper cap split open.

It sounds like it is more practical and easier time wise to just replace all the electrolytic ideally since disconnecting one lead is already half the work.

What is the easiest way to remove old can caps? And what about the simple axial stand alone ones? Luckily this tv does not have a ton of electrolytic just a handful or so. The frustrating thing I noticed is how hard it is to find the higher value ones that are both high voltage and high mf. Even on digikey it appears that some of the ones I need are just not in production anymore.

[Lain94]

Originally Posted by AlanInSitges

Don't trust that; electrolytics in the power supply and sweep circuits need to be replaced. Same with the paper caps in power supply, sweep, and audio. But for next power up, electrolytics.

Will definitely make sure to replace them now that I know that ESR is not necessarily telling the whole story about the health of these caps.

From what I have read online though the ceramic ones should be fine still as they are VERY reliable. Which seems to make sense as I have yet to ever run across a bad ceramic cap yet in all my time of working on electronics (albeit almost all of my experience had been vintage 80s and 90s computers)

It is just funny how it always seems with any electronics 30 years and older, solid state or not, computer, tvs radios ect almost always start having issues with capacitors. I would say nearly every issue I had was a capacitor related problem.

I mean were electrolytics not as reliable decades ago or is it just age catching up with them?

[Electronic M]

You don't need to remove can caps unless you are planning to restuff them using the unroll the bottom crimp method. You can just disconnect all the positive leads from the cans and wire new caps in elsewhere. If you do want to rebuild the (pull off cardboard sleeve if present) cut can ~1" up from base, drill holes in base so wires from inside can reach terminals, install new cap bundle and cover with cardboard sleeve (or metal foil tape top back on) method is faster and poses less risk of accidentally stabbing your own hands multiple times (I've tried both methods ask me how I know).

Old capacitance standard values went 1, 2, 3, 4, 5, 6, 7, 8, 9 (and powers of 10 multiples there of)
new capacitance standard values go 1, 2.2, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2, 9.1 (" ")

So if you can't find an out of production 200uF lytic go look for a 220uF...In fact look for it anyways because if you find the old 200uF it'll be MUCH more expensive. Lytics usually had more than 20% tolerance on capacitance.

Never order a cap with a lower voltage rating than the original.

Mouser and digikey have capacitance and voltage filters to make searching easier.

[Lain94]

Originally Posted by Electronic M

You don't need to remove can caps unless you are planning to restuff them using the unroll the bottom crimp method. You can just disconnect all the positive leads from the cans and wire new caps in elsewhere. If you do want to rebuild the (pull off cardboard sleeve if present) cut can ~1" up from base, drill holes in base so wires from inside can reach terminals, install new cap bundle and cover with cardboard sleeve (or metal foil tape top back on) method is faster and poses less risk of accidentally stabbing your own hands multiple times (I've tried both methods ask me how I know).

Old capacitance standard values went 1, 2, 3, 4, 5, 6, 7, 8, 9 (and powers of 10 multiples there of)
new capacitance standard values go 1, 2.2, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2, 9.1 (" ")

So if you can't find an out of production 200uF lytic go look for a 220uF...In fact look for it anyways because if you find the old 200uF it'll be MUCH more expensive. Lytics usually had more than 20% tolerance on capacitance.

Never order a cap with a lower voltage rating than the original.

Mouser and digikey have capacitance and voltage filters to make searching easier.

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.

[Notimetolooz]

Here is a page from a very useful website "Phil's Old Radios".
He has many articles about restoring various radios and TVs. (Radios and TVs are mostly made of the same kind of parts.
https://www.antiqueradio.org/recap.htm

I hope you are not confusing your capacitor types.
Here are some general guidelines.

"Paper caps" are capacitors that use paper (sometimes soaked in oil) as the dielectric (separator). The outer case can be many things, like a cardboard
tube sealed with wax, a ceramic tube sealed with wax or plastic or a molded plastic case. Most paper caps were phased out before about 1970.
All paper caps should be replaced with ones using a plastic film instead of paper.

"Ceramic caps" are often small ceramic tubes with wire bonded to the ends or (more recently) discs of ceramic with wire leads coated with ceramic.
Unless physically damaged ceramic caps are nearly always fine.

"Mica caps" early on are rectangular stacks of mica sheets with wire leads that have a molded plastic case. Modern ones are dipped in a epoxy like brown plastic. Mica caps are MOSTLY fine. Try not to twist old rectangular cases micas around the leads, that could cause the seal to fail. Some in circuits with a large voltage difference across them or large pulses have been found to fail.

Many times ceramic and mica caps are used in tuned circuits, if you replace them the new caps will not be exactly the same and you will need to re-tune the circuit. That can take special equipment.

The most unreliable caps are electrolytic. Because they contain liquid or at least moist paper they eventually fail. Generally I replace electrolytic caps if they are older than 40 years.

Keep in mind that these guidelines are based on probability. Some people come back from Las Vegas with more money than they started with, but not many. Also no one ever made radios or TVs to last forever.