Last winter I acquired a 1969 Motorola Color Vacuum tube tv. HT-617CW is the service model number. D20TS-921-D02 is the chassis model number. It appears to be a VERY high hour set from what I know about it. The color driver pots are turned ALL the way up. The tv has changed hands many times in its life. Was once used in a barber shop for awhile until 1990 when it needed repair work done on it. The person I got it from fixed it back in 1990 and ended up keeping it after customer would not pay up for repairs. It was in use throughout the 90s through the early 2000s then sat in a basement in humid Massachusetts until Late 2021 when I was given the tv by the now very busy and retired repairman.

The tv did work when I tried powering it up with a variac. No issues at first but when I turned the tv off I heard a loud "pop" sound and upon examining the inside of the tv their were two burnt carbon comp resistors with char rings around them, along with a ceramic cap that was burnt up (locating right at where the mains voltage comes into the tv) It looks like a filter cap may have bit the dust and open shorted. The #2 wire fuse on the top of the chassis is also burnt out and gone, no trace of it left. The circuit breaker fuse also tripped. I already replaced the two burnt resistors but obviously that is not all that will be needed to repair this thing. It looks like it was NEVER recapped at all in its life as far as I can tell.

I have been on a waitlist since January 2022 to get this thing fixed at a repair shop an hour away in Mass. I have virtually zero experience working on vacuum tube electronics of any kind. I am more used to working on vintage computers which is my main specialty. I am really eager to get this thing fixed but am puzzled as to why it worked fine when it was turned on with the variac gradually but it shorted somehow when it was turned off after a few seconds.

Any information at all about this tv or what may have happened is appreciated.

It's a handsome set, I hope you can get it repaired.

That ceramic across the line looks fine. It should be replaced regardless.

Most likely what happened was one of those filters was leaky and overheated while it was powered on. It was coincidental that it finally vented right when you turned it off. You really need to replace the electrolytics in the power supply, the fuses, and that across the line cap, then power up again slowly. I'd probably check the diodes in the power supply first too. None of that is particularly difficult to do, so you might want to try that yourself and see how far it gets you.

That is a great set but very dirty too. Make sure all those tubes are tested, then you can tighten up the socket pins.

Clean all pots with DeOxit and rotate 25 times each. The lousy parts are few but generally, some of the electrolytics may be all you need.

Otherwise the 1967-68 Motorola sets are about as rugged as a Zenith.

Very very nice find. I would love to find one like that...way overbuilt in a good way.
Should be fun to work on.

I've got a virtually identical set. Mine came out of the basement of a reapir shop in Indiana and needed rust treatment and a cataract removal (mine was MUCH worse than yours). It needed a few caps (I think several of the lytics we're bad) some adjustments and a focus divider arcing fix.
These use the SODPIL single tube color demodulator so it's almost as simple as a monochrome set.

Thanks to everyone for your comments and advice. I have to admit, when I first opened this tv up I was super intimidated by how complex it was and the rat's nest of wires and components under the chassis.

I am 27 years old so I never really grew up with vacuum tube tv sets, just the solid state CRT ones which look way less complex. It is mind boggling how much tvs have changed both in size and design over the last 50+ years.

The main reason why I had been hesitating to work more on this set was a combination of my lack of experience with anything vacuum tube related and just the fear of accidently messing something up or making the situation worse with the tv.

I get the feeling that these color table top tube tvs are hard to find, as I tried and tried to look for other similar sets and they seem to be nearly extinct. So I want to make sure that the repairs are done properly.

I have every intention and desire of getting this set fully restored to it's peak functionality. eg. getting rid of it's minor but annoying cataract, rejuvinating the high hour crt if possible or finding a replacement, cleaning the rust and dust off, recapping, ect. Basically give this thing the full TLC.

I wonder if you remember how you turned off the power.
Did you turn it off with the TV switch or did you turn it off with a switch at the variac?
The variac is a large coil, turning the power off to it can cause an inductive kick-back and produce a voltage spike. The voltage spike could cause something on the TV power input to short.

Trying to rejuvenate a color CRT is very iffy, there is a good possibility that it could make the CRT worse.

Color set can get out of adjustment and require a pattern generator to correct the convergence, etc.

When this set was produced a color TV was the most complicated electronic device in a home by a wide margin.

SS sets 1980 and newer are typically several times more complex than anything from the tube era....The difference is SS sets hide their complexity in integrated circuit chips and by encapsulating much of the wiring in the PCB. Tube sets every component is serviceable.

If your set is like mine it's a 25XP22 CRT (I forget if mine is a AP, GP or XP, but they're all interchangable) which is a major blessing. The 23" and larger console CRTs are MUCH easier to find than the 22" and under table model /mini-console CRTs. Basically all console sized delta-gun CRTs (and a good portion of table model CRTs) the same envelope size are compatible. They made delta gun rectangular CRTs from 1965-around 1980 when inline gun tubes replaced them in new TVs. There is one thing to be aware of in 1968 the US government passed a law changing CRT size measurement from the industry standard of glass bulb diagonal to being the diagonal measure of phosphor screen viewable area. So the same tube made in 1967 as a 25XP22 would be labeled as a 23VXP22 if made in 1969.

There's tons of worthless SS 70s consoles in ugly Mediterranean cabinets with compatible CRTs out there like Zenith CCIIs and RCA XL-100s (granted the XL-100 name lasted far past the end of the delta gun era). Zenith came out with black matrix CRT technology (calling it Chromacolor) in the 1970 model year and RCA and others soon licensed it, and it is a MASSIVE improvement in picture quality. The Zenith Chromacolor CRTs tend to be VERY long lived. I've upgraded some of my 60s sets to 70s Zenith black matrix tubes and it always makes a nice improvement in picture.

SS sets 1980 and newer are typically several times more complex than anything from the tube era....The difference is SS sets hide their complexity in integrated circuit chips and by encapsulating much of the wiring in the PCB. Tube sets every component is serviceable.

If your set is like mine it's a 25XP22 CRT (I forget if mine is a AP, GP or XP, but they're all interchangable) which is a major blessing. The 23" and larger console CRTs are MUCH easier to find than the 22" and under table model /mini-console CRTs. Basically all console sized delta-gun CRTs (and a good portion of table model CRTs) the same envelope size are compatible. They made delta gun rectangular CRTs from 1965-around 1980 when inline gun tubes replaced them in new TVs. There is one thing to be aware of in 1968 the US government passed a law changing CRT size measurement from the industry standard of glass bulb diagonal to being the diagonal measure of phosphor screen viewable area. So the same tube made in 1967 as a 25XP22 would be labeled as a 23VXP22 if made in 1969.

There's tons of worthless SS 70s consoles in ugly Mediterranean cabinets with compatible CRTs out there like Zenith CCIIs and RCA XL-100s (granted the XL-100 name lasted far past the end of the delta gun era). Zenith came out with black matrix CRT technology (calling it Chromacolor) in the 1970 model year and RCA and others soon licensed it, and it is a MASSIVE improvement in picture quality. The Zenith Chromacolor CRTs tend to be VERY long lived. I've upgraded some of my 60s sets to 70s Zenith black matrix tubes and it always makes a nice improvement in picture.

I checked the tv and the picture tube has a label on it that says "21GWP22" I am unsure though if this is the original picture tube that came with the set when it was new though.

I wonder if you remember how you turned off the power.
Did you turn it off with the TV switch or did you turn it off with a switch at the variac?
The variac is a large coil, turning the power off to it can cause an inductive kick-back and produce a voltage spike. The voltage spike could cause something on the TV power input to short.

Trying to rejuvenate a color CRT is very iffy, there is a good possibility that it could make the CRT worse.

Color set can get out of adjustment and require a pattern generator to correct the convergence, etc.

When this set was produced a color TV was the most complicated electronic device in a home by a wide margin.

I do remember turning the tv off directly on its own power/volume knob, the variac remained on and at the same voltage when the popping noise occurred in the seconds after tv was shut off.

That ceramic across the line looks fine. It should be replaced regardless.

Most likely what happened was one of those filters was leaky and overheated while it was powered on. It was coincidental that it finally vented right when you turned it off. You really need to replace the electrolytics in the power supply, the fuses, and that across the line cap, then power up again slowly. I'd probably check the diodes in the power supply first too. None of that is particularly difficult to do, so you might want to try that yourself and see how far it gets you.

Yeah that makes sense to me I figured it was a capacitor issue. I traced down the likely origin of the problem as being somewhere in the power supply circuit.

Diodes going bad? I did not ever think to suspect diodes could fail, were early diodes more prone to failure back then?

Also what are your thoughts on there being performance issues caused by all those old carbon comp. resistors? I know they are notorious for drifting upwards in value as they age. They are also noisy usually. The issue though is that carbon film resistors will introduced inductance into the circuit which I heard apparently may cause issues in a vacuum tube circuit. Is it worth messing with replacing all the carbon comps and if so what should I replace them with?

I checked the tv and the picture tube has a label on it that says "21GWP22" I am unsure though if this is the original picture tube that came with the set when it was new though.

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!

Yeah that makes sense to me I figured it was a capacitor issue. I traced down the likely origin of the problem as being somewhere in the power supply circuit.

Diodes going bad? I did not ever think to suspect diodes could fail, were early diodes more prone to failure back then?

Also what are your thoughts on there being performance issues caused by all those old carbon comp. resistors? I know they are notorious for drifting upwards in value as they age. They are also noisy usually. The issue though is that carbon film resistors will introduced inductance into the circuit which I heard apparently may cause issues in a vacuum tube circuit. Is it worth messing with replacing all the carbon comps and if so what should I replace them with?

Shorting of electrolytics in the power supply could kill the diodes.

My approach to resistors would be to first see what circuits have problems and then test the resistors, rather than a blanket replacement. The small inductance of a spiral resistor is not likely to cause trouble unless it is actually carrying high frequency signals (IF or RF). In the typical case, resistors in these circuits are bypassed by small capacitors anyway. In tube circuits, stray capacitance can be an issue, so component placement and lead length can have an effect, again, mostly in the IF and tuner. So, I wouldn't worry about the resistor type in video and sweep circuits, but have a bit of caution when working in the IF and especially the tuner.

The most likely parts in electronics of that era is the electrolytic capacitors.
That is why the best thing to do is assume they are bad before applying power.
Semiconductors are easily damaged by excessive current or voltage. A tube can withstand an overload for a few seconds but semiconductors will die in an instant, often without making a sound or without any smoke.
Of course any part can go bad. Many times TVs or radios are retired because something went bad and the owner doesn't want to bother getting it fixed.

Yes, stay away from the IF and Tuner since you don't have the test equipment for readjusting them. An exception might be carefully cleaning the contacts in the tuner.

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.

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".

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/353558980438?hash=item5251c1e756:g:yuYAAOSwTyhg4B5 0

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.

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!

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.

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.

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.

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.

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.

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.

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?

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.

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.

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.

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.

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.

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.

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

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.

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.

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?

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.

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.

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.

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.

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.

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:smoke:
LFOD !

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:smoke:
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.

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.

Ok, I am now replacing just the problem capacitors for now, but the wire fuse in the power supply circuit blew so it looks like I will need a "#31 copper wire fuse" Not sure how many amps that was or what voltage rating I need though, the schematics say nothing about that. Assuming #31 means SWG than I believe that would be 8 amps. But I still need to know how many volts minimum I need for the fuse to be safe to use as a replacement.

Or just buy some 31guage wire and use the same approximate length as the original #31 fusible wire link....

I just realized there were two standards SWG and AWG. Apparantly AWG is the now more commonly used one. It does not specify whether is AWG or SWG. But SWG was a british made standard and AWG is American so I am guessing AWG. I will post an update on results after replacing the burnt fuse and bad capacitors. If I am lucky the tv will fire up without issues after appropriate repairs are made.

This wax paper safety cap. that blew appears to be on the AC side of the circuit. From what I read online electrolytic caps are not supposed to be put in for AC voltage. Also AC and DC voltage ratings for caps. are often different. Finally this wax paper cap. only shows the DC value and not AC value. This cap appears on the schematic as polarized but wax paper caps are not polarized caps. I am very confused yet again.

https://imgur.com/a/xBRTFcF

Also for replacing that wax paper safety cap I mentioned: Would this be an acceptable replacement?

https://www.mouser.com/ProductDetail/CDE-Illinois-Capacitor/154MWR400K?qs=3tP%252BN51vMXex5fEmAOx7Mg%3D%3D

https://media.discordapp.net/attachments/705916049232756757/1021278042141765632/unknown.png?width=687&height=478

The original appears to be a ceramic bodied paper cap....Prior to the 80s those were common in across the line RF filter duty.

You could get away with the cap you've found (I often use normal 630V film caps), but modern standards call for a X or Y rated across the line safety cap.

AC voltage is rated in RMS which is basically set up so if you had a 120V light bulb it would reciever the same energy from 120VAC RMS as it would from 120VDC which was useful a century ago when some regions had DC power and others had AC. Peak AC voltage is the square root of 2 (or 1.414) times the RMS. Peak AC voltage (about 170V) is the max instantaneous DC voltage that the cap should normally see, but usually at least double that is used as a DC rating to provide a safety margin and help the cap run cool.
It's important to know that RMS should only be applied to sine waves...Non-sinusoidal waveforms need more complex math to get RMS values, and often don't measure accurately on most AC meters since most lack a true RMS measuring circuit.

An update on the Motorola tv. I have replaced the wax paper safety cap that had blown along with the blown wire fuse. In addition I have recapped 2 additional electrolytics and what was later discovered to be a paper-oil cap. I still am going to recap any remaining paper and electrolytic caps in the tv. I have managed to get the tv back to working condition, but it appears to still need adjustments, likely convergence, color purity, and perhaps also tuning. I am suspecting perhaps a weak horizonal output tube as well since the right side of the picture is wavy sometimes.

I attached some photos to show the current status now after making the basic repairs.

https://imgur.com/a/4AimE3e

If the side is wavy that's usually AC hum on the DC rails indicating filter capacitor (or sometimes B+ doubler diode) failure.

The raster not filling the screen horizontally is potentially a sign of a weak horizontal output/damper, but could also be a sign of B+ being below spec (which could be a result of the items from the previous paragraph).

B+ voltages and tubes should be checked.

Purity and convergence aren't hard to adjust if you have the right test patterns and sufficient patience... Dynamic convergence typically requires adjusting coils. Make sure you have a plastic hex diddle stick (AKA alignment tool). Do NOT use a metal hex key. Metal keys crack the adjustible slugs easily (which is very bad), and even if you have the godlike finesse/luck not to crack them the metal tool will it's self skew the adjustment such that if you have it perfect then it will be slightly off the moment you remove the tool. These are lessons I learned the hard way on convergence don't repeat my mistakes.

A bit of a minor update. I recently acquired my first CRT tester. It is a Sencore CR 161. From what I have heard online, Sencore is a trustworthy brand. After reading the instructions and manual, I quickly learned how to use the tester and began using it to test all the CRT's I have.

The one in this motorola tv is supposed to be 6.3 volts and hi bias mode. At this voltage red and green color guns were good. Blue however was on the weak side. However at 7.3 volts which would simulate what a tube brightener would do to the emissions, emissions improved for all three guns notably, and blue went solidly into the good territory.

No shorts were found for this CRT which is good to know.

While this CRT has many hours on it, I am a bit surprised that emissions seemed higher than I would have guessed based on the alleged history and heavy use of this tv over the decades (barber shop tv). I was fairly impressed.

I used Deoxit 100 to spray into the CRT socket and tube sockets...I think I screwed the tv up. I am now only getting a horizonal line that changes color but no vertical deflection. (Same symptoms as the Heathkit tv before it ultimately failed and now has no picture or signs of life) Does Deoxit 100 cause shorting?

I fear I may have ruined the heathkit tv and likely burned the yoke coil. I turned the motorola tv off. as soon as I saw the horizontal line. (It got to that point with normal audio when the variac was turned up to around 80ish volts or so) Normally the picture gradually expands out. Also of note is that I used 99% isopropyl rubbing alcohol to try and clean the grimy pincushion circuit board (The tv sat for several days so what little water was in the mixture likely dried off for sure), I wonder if it smeared grease around on the board and may have caused a short there. I am at a loss and pretty discouraged that the tv is now worse off than where it was before.

On tube TVs at least, you generally can't harm the yoke with loss of deflection. The CRT will typically be fine as long as you turn down the brightness, or catch it reasonably fast.
Vertical sweep failure will be cause by the vertical circuit, if you disturbed it look at what you disturbed, if you didn't then check voltages against schematic and report back with a comparison and we can help you interpret.

Check the service / normal switch first. It often gets bumped or dirty.
See how the CRT looks after set-up. If the blue looks bad you
can do a clean & balance to perk things up. I wouldnt go to
a full rejuve.

73 Zeno:smoke:
LFOD !

Ok, it looks like it was just a loose connection and I made sure all connections were secured this time. Vertical deflection is back. I tried my best to fine tune the rf signal i was getting from the digital to analog converter box. Also adjusted AGC, Contrast, brightness, horizontal sync, vertical sync ect. I also used my color king test pattern generator.

Based on the photos the convergence is way off and possibly color purity as well. But the most important issue to fix is the weird multiple images that seem to occur along the horizontal.

I am going to check the horizontal sweep frequency later with my oscilloscope and see that the horizontal sweep is at 15.75khz.

I suspect leaky caps in the horizontal circuit possibly. As for the lack of green color. This was later found to be a simple issue with the green video driver pot. on the drive board. It is just a bit finicky and I forgot to clean those. So green does work just did not realize the issue with that until photos were already taken.

https://imgur.com/a/ZcWcEWl

Pro tip for adjusting horizontal frequency with a scope: first scope composite video from a DVD player or other precise stable signal source, set the horizontal time axis of the scope for 2-3 horizontal sync pulses on screen (from this point on don't touch the time scale of the scope), count the divisions between leading edges of pulse tips, then hook the scope to the TV and adjust the TVs horizontal osc coil (hold pot centered if present) so the number of divisions between peaks is the same number counted with no signal applied to the TVs tuner...When you connect signal it should be locked without having to touch any controls after doing that.

Also, should I be wary of whether or not the oscilloscope can handle the high voltages in the horizontal sweep circuit? This oscilloscope is one of those digital chinese ones you can get for around 100-150 bucks. I just did not want to fry the oscilloscope by feeding it voltages far higher than what it may be designed for. The model of this Oscilloscope is ADS1014D. The manual says it can handle up to 400V voltage continuous which is far lower then what voltages are likely to be encounterd in the horizontal circuit.

Also, should I be wary of whether or not the oscilloscope can handle the high voltages in the horizontal sweep circuit? ...

Definitely should be wary. Don't try to measure the horizontal output plate, the damper, HV rectifier, focus rectifier, or anything on the flyback transformer.

The exceptions that are OK to measure are lower voltage pulses like those for AGC or burst gate - but measure those in the circuits where they are used, not at the flyback itself, to prevent accidentally contacting a higher-voltage terminal.

All diodes have now been tested in circuit using both my multimeter and my capacitor wizard (the manual claimed it could find shorted or leaky diodes in circuit).

All diodes seem to be ok, no shorts, none are open, and all are behaving as they should on the multimeter including the two that the sams photofact said to check if horizontal frequency is off. So that now leaves tube V8 as the last thing the photofact suggests checking. This is a horizontal oscillator tube the voltage levels going through this tube are far lower than from other tubes such as the horizontal output. Would it be safe to measure at one of the pin on this tube? Max voltage going through this tube per the schematic is about 275 volts, other pins on tube have lower voltages.

Should I suspect this tube as possibly being weak? Obviously heater is ok as this is a series string set and I doubt any shorts since that would cause other electrical issues and symptoms. The tube is 6GH8A. I do not have this tube but supposedly I may have some tubes that can substitute for it and have the same pinout and heater voltage and current such as 6EA8. Is it OK to substitute 6GH8A with a known good 6EA8 for this circuit and application to rule out a bad tube?

Update:

Doh! I did not realize that the diodes X11 and X12 were germanium and not silicon ones. Most of the diodes in the tv are indeed silicon but these two are germanium. They are painted black on the glass which confused me. I pulled them both off the tv and noticed the voltage drop as being .50V to .60V for both of them during the multimeter diode function test which is way too high for germanium 1N34A diodes. Voltage drop should be about .3V

So I got two replacement germanium diodes which were the correct voltage drop and soldered them in place.

Also the 6GH8A tube has been tested by my recently acquired and working EICO 667 tube tester. The 6GH8A in this tv appears to be an original one. There is SOME leakage but not an unacceptable amount among the elements. The emissions are just barely in the red weak zone. I compared the emissions to a known good NOS RCA 6GH8A and sure enough the NOS tube had very good emissions and no short or leaks.

I replaced all three can caps as well at this point finally with quality nichicon ones, Hopefully this will all make a difference.

Another Update: Well I think I made a mistake. Apparantly those diodes were in fact silicon ones. Apparantly a long long time ago a company made "Transitron" branded glass package silicon diodes....

The motorola tv has a total of three of these, two of which were x11 and x12...which I replaced with 1N34a diodes...

What is strange is the photofact part list says they are 1n34a which confuses me. Everything else on the part list matches up. The only things that did not were the lack of a remote control unit or FM/AM radio built in.

It is almost as if they later started putting in these silicon diodes instead of the germanium ones.

Any idea what this is all about?

They are glass painted black with a green arrow on one end and two yellow stripes on the other end.

I could find almost no information at all about these diodes on line and not a single image or photo of them aside from a very old black and white photo of one on a product catalog from the 1960s.

Here are some pictures of what one of them looks like.

https://imgur.com/a/20mRzIC

I've seen those in the Japanese electronics from the same era, they're germaniums. Had a nearby lightning strike take out the chroma and phase detect diodes in my T940 Magnavox, got creative with some wafer sockets and 6AL5's to replace them.

Can you identify the resistor that is burned in half just adjacent to the diode in your last picture? Looks like it might be a 33K (orange, orange, possibly a 3rd orange) You can see scorching in the area? Did I miss a reference to this in an earlier post?

Nice TV!

Oh yeah that resistor was one of two that actually did get burnt and failed open. I had it replaced way back quite some time ago. I should clarify that these pictures are older ones I took of this tv the first time I actually looked at the chassis.

I think those two resistors either were already burnt or got that way back when I had that ceramic shelled wax paper safety cap fail way back. (This issue was fixed and was not too hard to fix once I realized what had happened)

Last year I acquired a delta gun TV, and at testing, I'm desperate due to lack of any image. And a faint image appeared with bias pots maxed out. I think the CRT was dead. But then I noted that the G2 bias caps are paper-in-oil, and I decided then to change it for polypropilene caps. Voilà! Image back, with great brightness, at middle of adjusment!
The bias normally have relatively high DC resistance, so bad caps can upset correct adjustment.
If you not checked yet, is good to check if cathode, G1 or G2 have messed DC voltages due to leaky caps or drifted resistors. Also serves for various other faults you have found or will encounter. Unfortunately, older sets are not so reliable like 80's+ sets...

Last year I acquired a delta gun TV, and at testing, I'm desperate due to lack of any image. And a faint image appeared with bias pots maxed out. I think the CRT was dead. But then I noted that the G2 bias caps are paper-in-oil, and I decided then to change it for polypropilene caps. Voilà! Image back, with great brightness, at middle of adjusment!
The bias normally have relatively high DC resistance, so bad caps can upset correct adjustment.
If you not checked yet, is good to check if cathode, G1 or G2 have messed DC voltages due to leaky caps or drifted resistors. Also serves for various other faults you have found or will encounter. Unfortunately, older sets are not so reliable like 80's+ sets...

I noticed that there were a relatively large number of paper oil caps in this tv as they are many of these older sets from the early 1970s and earlies. I definitely am going to end up eventually recapping all the electrolytics, any remaining wax papers I may have overlooked and the paper oil ones too.

Even if the ESR has not went bad yet, they can still be leaky as I have learned is often the case when at operating voltages.

I've seen those in the Japanese electronics from the same era, they're germaniums. Had a nearby lightning strike take out the chroma and phase detect diodes in my T940 Magnavox, got creative with some wafer sockets and 6AL5's to replace them.

Yeah I was hoping they were germaniums like the part list said. It is just so confusing to me because of how obscure these particular brand are. Did they made both silicon and germanium ones to look like that with the green arrow and yellow lines? And ouch sorry to hear about the lightning strike...I know a great number of electronics falling victim to lightning strikes including a now very rare Monorail computer I had back in the 1990s.

And you replaced diodes with 6AL5s? That sounds pretty interesting, I actually had the same thought in my mind about replacing unreliable germanium or even early silicon diodes with some vacuum tube diode equivalent. Care to send me info about how you did the mod to the tv?

I always wondered what a vacuum tube tv would look like if even all the diodes were tube as well as opposed to selenium, silicon, or germanium.

The mod was easy enough, just a couple of those wafer sockets and some thin wire. Follow the basic diode cathode & anode connections and find 6.3v to run the heaters. The thing about the 6AL5 is there is no junction "breakdown" voltage, they will forward conduct at once there is heat on the cathode with only a few pf of capacitance. The only downside if you will is the heater to cathode capacitance and the need to decouple the heater itself beyond a few MHz.

The real b**ch of the lightning strike is it was roughly a mile down the road but it followed the telephone trunk and found its ground at my QTH killing several pieces with the EMP as the Magnavox was not even connected to anything at the time, it took out all of the germaniums for the chroma, phase det and the diodes in the AM/FM stereo tuner (combo set)

There were a number of variations of those japanese germanium diodes, some had a low forward while others were twice as high being they were stacked internally. A silicon diode has a forward bias of 0.72v while germanium is 0.3v at its knee point, I don't recall the number for those glass diodes you have but they were like lice in the early 70's stuff from the likes of Panasonic... they were everywhere.

"Pure germanium is known to spontaneously extrude very long screw dislocations, referred to as germanium whiskers. The growth of these whiskers is one of the primary reasons for the failure of older diodes and transistors made from germanium, as, depending on what they eventually touch, they may lead to an electrical short." (Givargizov, E. I. (1972). "Morphology of Germanium Whiskers". Kristall und Technik. 7 (1–3): 37–41.)

I noticed that there were a relatively large number of paper oil caps in this tv as they are many of these older sets from the early 1970s and earlies. I definitely am going to end up eventually recapping all the electrolytics, any remaining wax papers I may have overlooked and the paper oil ones too.

Even if the ESR has not went bad yet, they can still be leaky as I have learned is often the case when at operating voltages.

Understand I'm coming at this from being an audio guy... common wisdom in audio land is that electrolytics are always suspect after a couple decades, film types are usually good, ceramics can go either way, and PIO types are also usually good. Is there something about higher operating voltages in a TV set that makes PIOs suspect? I'm not saying you shouldn't check them, or even that that is wrong, I'm trying to learn here.

The paper/oil caps will pop without warning or provocation, electrolytics dry out and are known to go leaky both physically and electrically. Disk ceramics are quite stable and I've had numerous film caps go bad from being exposed to the high temps and voltages in vintage tube gear. Another to consider are the carbon comp resistors that get baked from radiated heat, nothing like a 6L6 or pair of KT88's to cook them. 50+ years of absorbing moisture cold only to be baked dry again when the heat is on, I'm also an audio guy and have over 40-plus years of experience with tubes so I know what you're dealing with. Case in point is my Magnavox T-940 AstroSonic. The IF gain would drift down as the set warmed up due to the resistors drifting up thus dropping the plate voltage. As an experiment I dynamically tested each resistor in circuit, Simpson 260 on the leads while heating the suspected resistor with a soldering iron at 45 volts (220F tip) and watched it drift up beyond the 10% tolerance rating. The set spent its first 14 years entertaining us kids, been in the family since new and it's going to get all new resistors in the near future.

The paper/oil caps will pop without warning or provocation, electrolytics dry out and are known to go leaky both physically and electrically. Disk ceramics are quite stable and I've had numerous film caps go bad from being exposed to the high temps and voltages in vintage tube gear. Another to consider are the carbon comp resistors that get baked from radiated heat, nothing like a 6L6 or pair of KT88's to cook them. 50+ years of absorbing moisture cold only to be baked dry again when the heat is on, I'm also an audio guy and have over 40-plus years of experience with tubes so I know what you're dealing with. Case in point is my Magnavox T-940 AstroSonic. The IF gain would drift down as the set warmed up due to the resistors drifting up thus dropping the plate voltage. As an experiment I dynamically tested each resistor in circuit, Simpson 260 on the leads while heating the suspected resistor with a soldering iron at 45 volts (220F tip) and watched it drift up beyond the 10% tolerance rating. The set spent its first 14 years entertaining us kids, been in the family since new and it's going to get all new resistors in the near future.

Interesting. My only experience with "really" old stuff is two receivers from the early 60s, which mostly used the axial "ceracaps" not the disc types like you're thinking of and a few electrolytics. I have been told by different people that the ceracaps are usually good and also that they're garbage, answer depends on who you talk to LOL. All I actually know is on my H.H. Scott receiver one of the ceracaps just got replaced because that and a couple weak tubes were what was keeping the MPX from working correctly. Most PIOs in audio land are actually for speaker crossovers and there they tend to have indefinite life. I don't think I've seen many films in tube gear, only more modern solid state stuff and again in speaker crossovers, so they don't get exposed to really high temps unless they're in a power amp and even then they're usually away from the output transistors.

Interesting. My only experience with "really" old stuff is two receivers from the early 60s, which mostly used the axial "ceracaps" not the disc types like you're thinking of and a few electrolytics. I have been told by different people that the ceracaps are usually good and also that they're garbage, answer depends on who you talk to LOL. All I actually know is on my H.H. Scott receiver one of the ceracaps just got replaced because that and a couple weak tubes were what was keeping the MPX from working correctly. Most PIOs in audio land are actually for speaker crossovers and there they tend to have indefinite life. I don't think I've seen many films in tube gear, only more modern solid state stuff and again in speaker crossovers, so they don't get exposed to really high temps unless they're in a power amp and even then they're usually away from the output transistors.

PIO caps in tube gear are usually Japanese made and usually found in Japanese made TVs (Motorola used some Japanese made parts as it was trying to get friendly with Matsushita), and they tend to be bad (electrically leaky).

The tubular ceramics were made by a variety of companies across 3 decades. I've seen some sets where they were fine and I've seen some sets where they were open or shorted. In GE Portacolors they tend to explode and spray bits of conductive foil all over the circuit board. In the newest application I'm familiar with Zenith 22-5001 safety caps used in CCII TVs of the 70s they're used in the flyback circuit and when they open they cause the HV to skyrocket, and if they short they trip the breaker on the TV...

The mod was easy enough, just a couple of those wafer sockets and some thin wire. Follow the basic diode cathode & anode connections and find 6.3v to run the heaters. The thing about the 6AL5 is there is no junction "breakdown" voltage, they will forward conduct at once there is heat on the cathode with only a few pf of capacitance. The only downside if you will is the heater to cathode capacitance and the need to decouple the heater itself beyond a few MHz.

The real b**ch of the lightning strike is it was roughly a mile down the road but it followed the telephone trunk and found its ground at my QTH killing several pieces with the EMP as the Magnavox was not even connected to anything at the time, it took out all of the germaniums for the chroma, phase det and the diodes in the AM/FM stereo tuner (combo set)

There were a number of variations of those japanese germanium diodes, some had a low forward while others were twice as high being they were stacked internally. A silicon diode has a forward bias of 0.72v while germanium is 0.3v at its knee point, I don't recall the number for those glass diodes you have but they were like lice in the early 70's stuff from the likes of Panasonic... they were everywhere.

"Pure germanium is known to spontaneously extrude very long screw dislocations, referred to as germanium whiskers. The growth of these whiskers is one of the primary reasons for the failure of older diodes and transistors made from germanium, as, depending on what they eventually touch, they may lead to an electrical short." (Givargizov, E. I. (1972). "Morphology of Germanium Whiskers". Kristall und Technik. 7 (1–3): 37–41.)

Germanium whiskers? Never heard of them, I learned something new today! I have heard of tin whiskers though and how they are a problem in particular with many old pots in electronics and can cause at best an annoying intermittent popping sound from shorts, or at worst cause a chain reaction of issues. I always knew germanium transistors were more prone to fail than the newer silicon ones. I also knew germanium transistors would blow up but I did not realize that germanium could grow whiskers!

I will look over the old tvs I am working on to see just how many germanium are in these tvs and test them all.

PIO caps in tube gear are usually Japanese made and usually found in Japanese made TVs (Motorola used some Japanese made parts as it was trying to get friendly with Matsushita), and they tend to be bad (electrically leaky).

The tubular ceramics were made by a variety of companies across 3 decades. I've seen some sets where they were fine and I've seen some sets where they were open or shorted. In GE Portacolors they tend to explode and spray bits of conductive foil all over the circuit board. In the newest application I'm familiar with Zenith 22-5001 safety caps used in CCII TVs of the 70s they're used in the flyback circuit and when they open they cause the HV to skyrocket, and if they short they trip the breaker on the TV...

Yeah sometimes they do actually work and are ok, it is kind of a gamble. I don't believe that wax paper ceramic caps can be reformed at all like electrolytics can they? Regardless after seeing what happened to one in my motorola, and how it just suddenly blew up and flung ceramic shrapnel out the tv....yeah I will never trust those caps ever again. Ceramic safety cap fool me once, shame on you old wax paper safety cap. Fool me twice? Not gonna be a second time for that lol.

Yeah sometimes they do actually work and are ok, it is kind of a gamble. I don't believe that wax paper ceramic caps can be reformed at all like electrolytics can they? Regardless after seeing what happened to one in my motorola, and how it just suddenly blew up and flung ceramic shrapnel out the tv....yeah I will never trust those caps ever again. Ceramic safety cap fool me once, shame on you old wax paper safety cap. Fool me twice? Not gonna be a second time for that lol.

Paper dielectric caps typically don't reform, and even if they do is it really worth the risk?

Germanium whiskers? Never heard of them, I learned something new today! I have heard of tin whiskers though and how they are a problem in particular with many old pots in electronics and can cause at best an annoying intermittent popping sound from shorts, or at worst cause a chain reaction of issues. I always knew germanium transistors were more prone to fail than the newer silicon ones. I also knew germanium transistors would blow up but I did not realize that germanium could grow whiskers!

I will look over the old tvs I am working on to see just how many germanium are in these tvs and test them all.

I've heard about this: https://nepp.nasa.gov/whisker/anecdote/af114-transistor/index.html about these transistors. According with this investigation, the can is responsible for wiskers in classic old transistors, but I don't know if germanium is also responsible in some form/model also.

Tin whiskers were job security for the GE MASTR guys as they would grow in the front end castings and short out the helicals causing the receiver to go deaf. They also used germaniums in the EP38A10 regulator section and they would often go on strike without warning taking the +10v supply down.

Paper dielectric caps typically don't reform, and even if they do is it really worth the risk?

What he said... ^^

Update as of last night: Primary issue of the "triple image" still not gone but performance of the TV is notably improved in other areas. Also decided to leave the NOS RCA 6GH8A tube in and just hold onto the old weak motorola one for now. Used deoxit on ALL the vacuum tube sockets and any other connectors or pots I could reach.

Then tested all the tubes. Confirmed that the only weak tube was the old 6GH8A all other tubes emissions are good and compared with known good NOS tubes. Cleaned the tv a bit more just for fun and my own satisfaction.

After completely recapping and replaced all of the three can caps with new capacitors and replacing the two diodes with 2 NOS germanium 1N34As:

1. It started right up just fine with no signs of trouble after replacing the stuff mentioned.

2. Horizontal triple image issue still is there but not any worse off than before.

3. The CRT picture tube can get way brighter now! Like WAY brighter in response to the brightness control on the front! WOW

4. Colors appear more vivid and pop out so to speak which was unexpected.

5. Fine tuning neon lamp indicator suddenly came back to life and now is always lit red the whole time. Should go out when fine tuning is correct. I know how to adjust the responsiveness of it and will do so later.

6. CRT makes a more satisfying sound when turned off suggesting a more thorough discharge when being turned off.

Conclusion: I am going to finish replacing remaining old electrolytic and any other remaining paper oil caps as well in the tuning and convergence circuits and any where else. I am also going to investigate the degaussing circuit further as it is obvious to me that it is not working. Appears to be controlled by some sort of relay.

Degaussing loop itself i measuring at 8ohms. Resoldered the antenna leads going to back of tv for a more solid connection.
Next will check diodes more closely once more, as well as focusing on old carbon comp resistors i the horizontal oscillator and AGC circuits for any that might be out of value range tolerance wise.

Beginning to suspect an issue with resistors or perhaps even a coil somewhere.

Wow! Ok Apparently It must have been a leaky capacitor. I replaced the capacitor on the CRT driver board and the small electrolytic capacitor on the pincushion circuit control board. I also used deoxit and cleaned the two pots on the pincushion board for the vertical and horizontal. I believe one of the pots even had some tin whiskers which I wiped off and blew out the others with some compressed air.

I tried to rotate the pots a bit to get them loosened and cleaned and tried to put them back where they were. They likely still have drifted a bit for sure and will need more adjustments later.

Put the old 6GH8A tube in as well before turning on just out of curiosity. Finally also replaced one of the carbon comp resistors in the horiz. osc. circuit and while it measured out of circuit as 6% off value when it should have been 5%, it is possible that value went up even more at operating temp.

Still amazing at how well the convergence is despite it not having been adjusted since 1980.

Now to fix the degausser and get it working again, then onto recapping remaining electrolytics and any other problem caps. Primarily the one in the FT1 circuit, an electrolytic on the conv. board. some caps in the tuning circuit ect. Cleaning tuner and pots of front controls as well.

Some photos showing the progression of the picture as the tv warmed up and from me adjusting controls.

https://imgur.com/a/wzbJ6sp

New Update:

Finally figured out how to get the tuner out and freed. Instructions were there the whole time on a rather dirty sticker on the back of the HV cage. Felt a bit silly after unscrewing every single screw but oh well.

I realized there were still some remaining paper oil capacitors in this tv, 2 were Jenson branded, one being 1uf 600V and the other being .47uf 600V. I am betting these are leaky and bad. I will replace those with mylar ones.

I also removed and recapped a small electrolytic that went from one of the lower control pot posts to ground. Used deoxit on remaining controls and pots and inspected everything. All bulbs look good but thought of replacing them anyways with 6.3v LED ones. Would it be ok to do so since the voltage is the same? or would the lower current draw somehow cause an issue? I would rather replace them with LED ones now to avoid having to open anything up later.

Then I recapped a cardboard shell electrolytic capacitor 100V 80uf with a 100V 100uf one. From what I understand it is ok to go same or higher with voltage. This particular one was in front of the horizontal centering taps in front of the HV cage. I figure it will be ok for a slightly higher capacitance.

Also realized one of the electrolytic capacitors in this tv is actually non polar. The non polar electrolytic cap is on the convergence circuit board. I am unsure what to do. I have a polarized electrolytic of the same value ready to go but even if it is ok to put in I will need to make sure it is going in the right way. Any ideas of what to do about this?

https://imgur.com/a/72zuFuE

A non polarized electrolytic capacitor is used when the circuit is primarily AC, biased with little or no DC voltage, so using a polarized one would be quite detrimental.

From some old makers datasheet, for "normal" electros I see that is possible to use with <10% rated voltage in reverse; ie. a 63V cap will survive to a "-6.3V" according with this. And this applies to a superimposed AC also.
If AC+DC is less than this rule of thumb, I think that is possible to use. Or at least for testing.
In fact, I accidentally prove it sometimes :scratch2: :D
Note: the maximum AC current is also to be in account, but is unlikely to be too high on a normal TV subcircuits.

From some old makers datasheet, for "normal" electros I see that is possible to use with <10% rated voltage in reverse; ie. a 63V cap will survive to a "-6.3V" according with this. And this applies to a superimposed AC also.
If AC+DC is less than this rule of thumb, I think that is possible to use. Or at least for testing.
In fact, I accidentally prove it sometimes :scratch2: :D
Note: the maximum AC current is also to be in account, but is unlikely to be too high on a normal TV subcircuits.

Of course, will be a waste of big size capacitor, but at least, guaranteed for testing.

Another thing to try for replacing a non-polar electrolytic cap is to get two polar caps, then wire them in series with opposite polarity. However, this may be a problem in high-current applications like the convergence circuit. Better to be safe and get an actual non-polar replacement.

What value and rating is this cap?

Another thing to try for replacing a non-polar electrolytic cap is to get two polar caps, then wire them in series with opposite polarity. However, this may be a problem in high-current applications like the convergence circuit. Better to be safe and get an actual non-polar replacement.

What value and rating is this cap?

The capacitor has a rating of 30uf and 25VNP with a tolerance of 20%.

Removed it already to test, and while the ESR was ok, I then used a simple capacitance meter that runs on a 9V battery. It measured the capacitance as being WAY out of spec like a bit over 300uf! Yikes!

Definitely bad.

It's more likely that the meter is not measuring it properly than the capacitance is 10 times larger. Can you post the schematic?

Found these 15 uF NP caps, you could use two in parallel if you can't find 30uF.

https://www.amazon.com/15uF-100V-Capacitor-Non-Polarized-Electrolytic/dp/B09TQVPL3M/ref=sr_1_6?crid=R3Q0LS5JQKSA&keywords=33+uF+non+polarized+capacitor&qid=1685242989&sprefix=33+uf+non+polarized+capacitor%2Caps%2C141&sr=8-6

You are not likely to find 30 uF these days, but standard value 33 uF is readily available:

https://www.parts-express.com/33uF-100V-Non-Polarized-Capacitor-027-350?quantity=1

Note the 33 uF cap I found is 10% tolerance, so will satisfy the 30 uF 20% requirement.

Wayne, I found these same 15mf and used one for a 25mf cap in a CTC3 convergence box for my 21CT55. I may now add one to get to 30mf to be above but closer to the RCA 25mf. Nice discussion on NP caps.

It's more likely that the meter is not measuring it properly than the capacitance is 10 times larger. Can you post the schematic?

https://imgur.com/a/4GUowLw

Here is a snapshot of where the cap is on the schematic. I managed to find a cap that is nonpolar and is 33uf and 25V with the necessary tolerance. Digikey has a FEW nonpolar electrolytic but not a ton sadly.

Also another unrelated question, i noticed both light bulbs for the tuners are 6.3v incandescent. You can buy 6.3V LED bulbs that are supposed to be drop in replacements. They seem to be popular with pinball machine restorers. Would this be safe to do despite the LEDs likely drawing far less current than the old bulb? I would prefer to switch them to LED to eliminate frequent replacing and for more brightness on the tuner controls

In transformer sets you can. It's not really necessary for bulb longevity though....The incandescent bulbs in there probably lasted 15-20 years of heavy service before they failed. I've got a 71 Zenith that I ran daily for 10 years of heavy use and the dial bulb has yet to be changed during my ownership.

This last part is more personal preference, but I can't stand LEDs in vintage gear. The color temperature, brightness and light pattern are all wrong and it looks garishly unoriginal...The only times LEDs are an advantage are when the material around the lamp likes to melt from bulb heat or if a power transformer in a radio is overstressed and you're doing everything you can (like installing SS rectifiers where the tube rectifier was).

In transformer sets you can. It's not really necessary for bulb longevity though....The incandescent bulbs in there probably lasted 15-20 years of heavy service before they failed. I've got a 71 Zenith that I ran daily for 10 years of heavy use and the dial bulb has yet to be changed during my ownership.

This last part is more personal preference, but I can't stand LEDs in vintage gear. The color temperature, brightness and light pattern are all wrong and it looks garishly unoriginal...The only times LEDs are an advantage are when the material around the lamp likes to melt from bulb heat or if a power transformer in a radio is overstressed and you're doing everything you can (like installing SS rectifiers where the tube rectifier was).

Silly question but how will I know if my tv is a transformer set? I do know that the tv has a power transformer in it. But the chassis is ground. CRT aquadag discharges to the chassis as well.

Silly question but how will I know if my tv is a transformer set? I do know that the tv has a power transformer in it. But the chassis is ground. CRT aquadag discharges to the chassis as well.

Looking at the schematic is the best way. Some sets were hot chassis and had a transformer. One of Zenith's first FM stereo tube table radios had a heater transformer but directly rectified AC and tied one leg of the AC to chassis. Some TVs had a transformer for B+, but series heaters tied directly to incoming AC with one lead going to the chassis...

If B+ and heater are derived from a power transformer you've got a pure transformer set, otherwise you have a hot chassis set with or without a power transformer.

Also some transformer chassis sets can develop shorts that make the chassis hot...That's something to beware of too...I had a TV repair isolation transformer primary to secondary short on me....I didn't realize till I got shocked...the fun way to find out! :yikes: :D

Looking at the schematic is the best way. Some sets were hot chassis and had a transformer. One of Zenith's first FM stereo tube table radios had a heater transformer but directly rectified AC and tied one leg of the AC to chassis. Some TVs had a transformer for B+, but series heaters tied directly to incoming AC with one lead going to the chassis...

If B+ and heater are derived from a power transformer you've got a pure transformer set, otherwise you have a hot chassis set with or without a power transformer.

Also some transformer chassis sets can develop shorts that make the chassis hot...That's something to beware of too...I had a TV repair isolation transformer primary to secondary short on me....I didn't realize till I got shocked...the fun way to find out! :yikes: :D

After looking at the schematic and the tubes on the schematic. It looks like the B+ voltage comes from the transformer but the heater voltage does not. I guess that answers my question lol. Luckily I have not been shocked by anything yet, well other than a can cap early on.

After looking at the schematic and the tubes on the schematic. It looks like the B+ voltage comes from the transformer but the heater voltage does not. I guess that answers my question lol. Luckily I have not been shocked by anything yet, well other than a can cap early on.

If you have not been shocked yet, then you have not been working with tube stuff long enough! :D

My finger still has not fully healed from the last shock I got and the reaction pulling back! :O

Status update:

All paper oil, wax paper, and electrolytic capacitors have successfully been replaced and correctly installed. The small exception being two low voltage electrolytic I overlooked on the pincushion circuit board, the third one I had replaced awhile back leading up to the horizontal oscillator frequency issue being solved.

I had taken the entire set apart and did a thorough examination of every wire and solder joint as I went along with the last major round of recapping. Performance has been improved notably with controls not causing bizarre things like effecting other things they should not be anymore.

Still fighting some minor pincushion issues notably with a bit of a curving in tendency on the left side of the image on the tv. Colors look amazing considering the emissions of the CRT and the brightness is more than ample for what I need. It does seem like a bit too bright in a sense because the dark parts of the screen that should be black are so bright that it is not making the contrast look good.

I decided to keep the NOS RCA 6GH8A tube in after using the original old motorola 6GH8A tube during my initial test run after the last recap. As I mention before the old tube had very poor emissions for the AGC part of the tube. The horizontal oscillator part of the old tube was better than AGC emissions but still very poor. The new tube makes the AGC control super sensitive compared to the old tube which necessitated me readjusting the other controls again.

Degausser still not working and no idea why, this tv does not use a thermistor or posistor but instead some sort of switch or relay.

https://imgur.com/a/9SmHDIM

Motorola was good for using some sort of electromechanical thermal delay device for automatic degaussing in the tube era instead of the thermistor arrangement everyone else used.

Motorola was good for using some sort of electromechanical thermal delay device for automatic degaussing in the tube era instead of the thermistor arrangement everyone else used.

Yeah and it turns out that Motorola actually invented their own unique way of degaussing their tv's using these special electromechanical switches back in the 60s. They were very innovative at the time. I am having a hard time though figuring out if it is basically a special relay and where I can order a NOS replacement. If they are a rare part I may opt for just wiring in my own little toggle switch that I can manually control at will. Anyone know anything about the degaussing switches that are on Motorola's? The degausser coil itself is fine and is not shorted or open from what I can see with my multimeter. It seems like the switch itself must have gotten stuck or failed.

Found the thermal switch that is responsible for controlling the degaussing action. I removed it and measured it. Looks like it failed. It is supposed to be open when tv is off, but then when the tv heats up it is supposed to close up and short. I could hear a rattling sound inside and the ohm values seem to be all over the place. It is a "klixon" brand. It has some random numbers on it which I looked up on google but could find no info at all on this part. Not sure if it is safe to simply replace it with a manual toggle switch or button, or perhaps a generic thermistor?

The degausser is the last major thing on this tv to get working. The pincushion circuit seems to be having some minor issues with curving on the left side but that may have to do with the adjustments and controls not being properly done right.

https://imgur.com/a/EAcy3QL

Update: Another dumb moment for yours truly turns out the Klixon brand thermal degaussing switch actually was fine all along. I am so used to most old tv's having the disc style posistors and thermistors failing that I just assumed as a given the degausser switch was bad as well...I was wrong and am kicking myself for it. First off there were no symptoms of the switch actually having failed since there was never any discoloration on the tv screen indicating that. I was looking for a problem that did not exist out of preemptive paranoia. Talked to an older gentlemen who is a semi-retired tv repairman and former zenith/motorola tv/radio dealer that has a repair shop a few hours away in my state. He told me I won't hear the degausser kick on nor see it work because it all happens BEFORE the screen even lights up. He also said this switch is special and I can not just put in a dumb one button switch to manual degauss due to it needing a specific ohm range.

Good news....despite ripping it off it appears to still be ok and work as before according to my multimeter and thus I then successfully rewired it back on and lengthened the leads and secured it back onto the chassis after a bit of patience and time.

Update: Another dumb moment for yours truly turns out the Klixon brand thermal degaussing switch actually was fine all along. I am so used to most old tv's having the disc style posistors and thermistors failing that I just assumed as a given the degausser switch was bad as well...I was wrong and am kicking myself for it. First off there were no symptoms of the switch actually having failed since there was never any discoloration on the tv screen indicating that. I was looking for a problem that did not exist out of preemptive paranoia. Talked to an older gentlemen who is a semi-retired tv repairman and former zenith/motorola tv/radio dealer that has a repair shop a few hours away in my state. He told me I won't hear the degausser kick on nor see it work because it all happens BEFORE the screen even lights up. He also said this switch is special and I can not just put in a dumb one button switch to manual degauss due to it needing a specific ohm range.

Good news....despite ripping it off it appears to still be ok and work as before according to my multimeter and thus I then successfully rewired it back on and lengthened the leads and secured it back onto the chassis after a bit of patience and time.

Yeah most degaussers work before screen light....One way to confirm operation is to stack another working tube color on top, have it running, then turn on the set with the questionable degaussing system and see if it momentarily disturbs picture on the working set...When you stack working sets and use them like that you get used to seeing this.

Update: Final two capacitors on Motorola replaced. Motorola is now 100% fully recapped and ready for final setup with HV, purity, static and dynamic convergence ect.

Turned on tv for first time since last two remaining electrolytic capacitors (they were on pincushion board) replaced. No noticeable improvements but not worse off either I suppose. The HV anode cup is quit rigid due to age. Could the anode cup being rigid cause any issue when trying to measure HV or cause issues with the raster or picture in any way? Is it a good or a bad idea to replace the anode cup? It does not seem to be a particularly costly thing to replace luckily as they were commonly made for many decades after vacuum tube tvs stopped being made since CRTs were still a thing into the 2000s.

Here is a image of what it looks like with a grid pattern on the screen. Seems to be possibly still having linearity issues or pincushion issues? Or do I just need to adjust control more?

https://imgur.com/a/F07YAyr

The only concern with the high voltage cup would be if it arced - no effect on picture otherwise.

The pattern looks vertically compressed near the very top. You can try adjusting the vertical linearity to see if it can be improved without bad results elsewhere. A DVD with an Indianhead test pattern might be helpful at this point.

Sometimes when the linearity is best over-all, it may be a bit out at the extreme top. This is the case for my RCA CTC-5. I don't know what could fix it, so I just use the best compromise setting. Maybe fresh tubes in the vertical section?

Anyone else have a idea what could be done to get closer to perfect?

Vertical issues seem to have improved with me adjusting the controls, along with patiently waiting for the tv to fully warm up for a full 20 minutes as recommended by the photofact for the tv. It is interesting that while the tv can generate a raster and image and become watchable in less than a minute, optimal performance indeed does take a decent chunk of time.

This should have been obvious to me but this is coming from someone who grew up with solid state CRTs and never actually used an old tube set let alone saw one up close up until I was given this tv for free.

Either way aside from the minor yellowish cataracts and slightly off dynamic convergence for blue, the picture is not bad considering the age of the tv and the hours the CRT has had on it. I am done with the restoration of this tv and have been able to enjoy watching this tv for hours at a time without any problems for a few days so far! Motorola really did a great job designing tvs....Ford Philco on the other hand...I am not very impressed. This tv is very rugged and seems to keep on going after a straightforward full recap.

I caught a typo in the Sam's photofact for this tv as well, it says you can sub a 6LF6 (the tube this tv uses for the horizontal output) with a 6BL6 instead...they meant 6LB6 I believe. A 6BL6 is a very uncommon tube that has a completely different pinout.

https://imgur.com/a/MJrNeaJ