Picked up this tv today, my favorite picture tube size, 17", going to make a project of restoring it.

One problem though.. Check out the asbestos around the yoke! Not sure how to handle this, for now just replaced the back.

Yank it off, throw it in the trash and blast it in the backyard with the compressed air. It won't kill ya to handle it for three minutes.

Yup. Try to be upwind from it so you breathe in as little of it as practically achievable.

What was the use of this asbestos? Did they install it to reduce the heat on the rear cover of the yoke which was famous for crumbling with age?

What was the use of this asbestos? Did they install it to reduce the heat on the rear cover of the yoke which was famous for crumbling with age?
That isn't original. Looks like someone put it on for some reason, maybe arcing.
Go to the dollar store and pick up some cheap dust masks, carefully sweep up the crumbs and the sheet and put in a plastic bag. It's not good to breath it, but the poor souls that died of Asbestosis were exposed to it, forty hours a week, for twenty or thirty years. :sigh:

If you can spray some light water mist on it, it wont release dust at all when you remove it. Theres gonna be some fibers inside the tv left over to blow out. The cheap dust masks only stop the bigger sized particles and its the micro size fibers that cause most the problems with repeated long term exposure. There are masks made for asbestos or those air supplied hoods, but for a one time thing I wouldnt worry much about it.

The horizontal output and damper are in a cage directly under the yoke, I think it's kind of a fix for a bad thermal design.

I think I have a handle on how to do this, need to pick up a good dust mask first. I hope there isn't more asbestos inside the HV cage, but I will leave checking that until after what's there now is cleaned out.

I bought a P100 respirator at home depot, which is marked on the package as good for asbestos.... Thought it best to spend a few extra bucks to prevent future hypochondria about inhaling asbestos fibers.

You're really overthinking it. You could legit hold your breath for the two seconds it takes to pull the thing off and put it in the garbage can. But hey, whatever makes you feel better.

I'm with mips on this one, take it outside and blow all the dust out.

You're really overthinking it. You could legit hold your breath for the two seconds it takes to pull the thing off and put it in the garbage can. But hey, whatever makes you feel better.

I'm with mips on this one, take it outside and blow all the dust out.


I think you're likely right, I just think better safe than sorry, I can be a bit of a hypochondriac sometimes, and for the minimal effort involved in getting a proper mask, wetting it down, not rushing, etc. I'd rather not worry about asbestos later on, next time I get a cough.

I got the circuit to this TV from a forum member, and studied it a while. This is my first B&W chassis which is line operated (no power transformer). It doesn't even have a voltage doubler, only a half wave rectifier and a very low B+ of 130V! I do like that the sound detector is an actual discriminator, and not the nasty quadrature detector my RCA and Philco sets use.. Fingers crossed it won't buzz?

I do have a nice 500kVA isolation transformer to make working on it safe. Once I get the chassis cleaned out I'm looking forward to checking the CRT and making sure it's a viable candidate for restoration.

Got the set cleaned up and disassembled. Tested the 17BJP4 CRT on my B&K 466, not looking good... Cutoff almost nonexistent, and emission bad. On the other hand, early Canadian TVs aren't exactly common anymore, and I do like how this one looks.

Got the set cleaned up and disassembled. Tested the 17BJP4 CRT on my B&K 466, not looking good... Cutoff almost nonexistent, and emission bad. On the other hand, early Canadian TVs aren't exactly common anymore, and I do like how this one looks.

The CRT just needs waking up. Probably lying dormant for several years.
BTW, that quite an isolation transformer you have there! :D
I know you meant 500VA or .5KVA. I've made that same error. :scratch2:

The CRT just needs waking up. Probably lying dormant for several years.
BTW, that quite an isolation transformer you have there! :D
I know you meant 500VA or .5KVA. I've made that same error. :scratch2:

haha, I'm always specifying 500kVA transformers at work, I didn't even catch that :)

So far I ran the CRT for 8 hours at 6.3V, and I also tried running it for 30 minutes at 8V. At 8V, emission is well into "good" (75/100 on the B&K 466), but at 6.3V, it's at the high end of the bad scale.

Even after letting it sit all night long at 6.3V, it's still reading bad. Cutoff only occurs if I turn down G1 to a bit less than 40V.

I think this tube will make a picture, but do you think it's realistic it will wake up more than this? I've had them come to life before, but this isn't looking good to me. Then again, I haven't done as many as most people here.

My b&k 466 will show mid to upper bad on monochrome CRTs that produce reasonably bright pictures on a healthy chassis.... Cutoff is only important on color CRTs...As long as you don't get all or nothing cutoff response adjusting the knob( that indicates gas).

The good bad scale is accurate for color CRTs where a good portion of the emission is lost at the shadow mask before it can reach the phosphor.

If it is somehow dim with the chassis working right just throw a brighter on it.

My b&k 466 will show mid to upper bad on monochrome CRTs that produce reasonably bright pictures on a healthy chassis.... Cutoff is only important on color CRTs...As long as you don't get all or nothing cutoff response adjusting the knob( that indicates gas).

The good bad scale is accurate for color CRTs where a good portion of the emission is lost at the shadow mask before it can reach the phosphor.

If it is somehow dim with the chassis working right just throw a brighter on it.

This is, of course, very encouraging news. The cutoff definitely isn't all or nothing, it basically just does nothing, unless you ease off on the G1 voltage, in which case cutoff works more or less as it would with a stronger testing tube.

I'm okay with a reasonably dim picture, just so long as it doesn't blow out and lose focus whenever there's a bright scene, or text on the screen. I think that with the above info a basic recap is more or less justified, just to find out how well it works.

If it is still dim once you get the chassis sorted out a mild rejuvenation should bring it back. I've had good results with B&W tubes after rejuvenation. They usually last quite well. Color tubes are much more difficult as you are trying to match three guns plus they don't seem to last as long after rejuvenation (less cathode material?)

I've also seen this tube (17BJP4) available as NOS, periodically, when I searched for it. Will keep the rejuvinate plan in mind.

One thing which threw me about this set, was how to get into it! I started by taking the back off, then the screws which hold the chassis in place, then the front panel... Then there was no reasonable way to get the control panel out, but I managed to somehow contort my hand.

When all was said and done I realized the whole set is built on a flat piece of plywood, which forms the bottom, and the front, sides and top all unscrew from this, leaving only the bottom. This will be great for working on the set but I sure wish I figured it out earlier!

Now just waiting for the rainy weather to end so I can take the chassis outside, and detail it with an air gun. The component side is quite dirty. I am curious if the old British made Plessey electrolytic cans have any life left, or need to go.

I've also seen this tube (17BJP4) available as NOS, periodically, when I searched for it. Will keep the rejuvinate plan in mind.

One thing which threw me about this set, was how to get into it! I started by taking the back off, then the screws which hold the chassis in place, then the front panel... Then there was no reasonable way to get the control panel out, but I managed to somehow contort my hand.

When all was said and done I realized the whole set is built on a flat piece of plywood, which forms the bottom, and the front, sides and top all unscrew from this, leaving only the bottom. This will be great for working on the set but I sure wish I figured it out earlier!

Now just waiting for the rainy weather to end so I can take the chassis outside, and detail it with an air gun. The component side is quite dirty. I am curious if the old British made Plessey electrolytic cans have any life left, or need to go.
I thought Plessey had a plant in Canada!
If the CRT is aluminized the picture will be reasonably good. Makes a real difference.
More pictures of the chassis would be great.

The chassis is full of British capacitors, hunts, plessey, and others. All the paper caps are from the UK. Canadian Marconi was British owned at that point. I have an earlier one with a round CRT which is in poor shape, but even has a British made focus coil on the CRT. That TV is unfortunately missing cosmetic parts, but is much older in design. One thing which seems to me a bit unique about Marconi sets is the IF sections are done in a straight line, they look a bit different from the US designed sets. The sets are a real mix of British parts and American design, sort of like our language and culture!

British Capacitors are quite common in the electronics which were made in Montreal in the 1950s and 1960s.

I got a new blow gun for my air compressor with a narrow tube at the end, this afternoon I plan to reassemble the set on its plywood base, and take a bunch of photos after I clean it more. One thing I noticed is the horizontal output tube is bad, the getter is white.

Here's some photos of the cleaned chassis.

Hey Max, if you need a horizontal output tube I more than likely have a number of them.

Gregb

Hey Max, if you need a horizontal output tube I more than likely have a number of them.

Gregb

Hey Greg, I managed to find a couple of NOS horizontal outputs with my tubes, however I am far from done with this project, there's 17 other tubes that could be bad, among other stuff.

I got all of the paper capacitors changed, and started measuring resistors. I'm surprised how many are 20-50% off, I've never had to order so many new resistors for a TV before. I am sure it would work as-is, but certainly not like new.

Decided I wanted to check if the flyback and other critical components work, before ordering any parts.

I replaced all the paper caps except two I didn't have on hand. I reformed the electrolytic filter capacitors without incident. Then I installed the CRT and powered on.. Up came a nice raster, and the blasting audio of a TV which isn't tuned into a station. It's even reasonably bright.. A rewarding sight after all the work so far.

High voltage measures 12kV, but the meter I used is always low, on every TV I work on, so I think it's probably right on 13.5 as the manual wants.

That's a great start. Youv'e even got a full raster. A few Australian sets had the IF's arranged in a straight line like yours (PYE, Astor). Some had them on a sort of sub chassis suggesting they were all pre aligned then simply dropped in during chassis assembly.

That's a great start. Youv'e even got a full raster. A few Australian sets had the IF's arranged in a straight line like yours (PYE, Astor). Some had them on a sort of sub chassis suggesting they were all pre aligned then simply dropped in during chassis assembly.

Were there any transformerless sets in Australia? 240V seems like a lot of filaments.

I really, really like my new isolation transformer. It's so luxurious to be able to work on a line powered device without being paranoid about safety.

There were a few transformerless models, Ekco being one of them but they were not popular in Aus at all since 240V is quite lethal and the possibility of contact with the chassis with Active and Neutral reversed scared a lot of people. I had an isolation transformer until very recently when It went up in a cloud of smoke and oozed black goo everywhere. It was a pull from an old Sony color set and had served me well for many years but didn't like being connected to a laptop charger (I was using the laptop to play audio at a party and had a ground loop causing digital noise in the background so used the iso tranny to get around it). Power factor correction in Chinese power supplies is non existent. As all the Transformerless TV's in Aus are long gone I don't think I'll worry about replacing it.

There were a few transformerless models, Ekco being one of them but they were not popular in Aus at all since 240V is quite lethal and the possibility of contact with the chassis with Active and Neutral reversed scared a lot of people. I had an isolation transformer until very recently when It went up in a cloud of smoke and oozed black goo everywhere. It was a pull from an old Sony color set and had served me well for many years but didn't like being connected to a laptop charger (I was using the laptop to play audio at a party and had a ground loop causing digital noise in the background so used the iso tranny to get around it). Power factor correction in Chinese power supplies is non existent. As all the Transformerless TV's in Aus are long gone I don't think I'll worry about replacing it.
The NEC and the CEC does not allow any voltage higher than 120 volts from live to earth ground in residential and smaller commercial installations. I always thought it was a safer approach than using a higher voltage for general usage. Copper wire is expensive here as well, but we never sacrificed safety for reduced expense.

Were there any transformerless sets in Australia? 240V seems like a lot of filaments.

I really, really like my new isolation transformer. It's so luxurious to be able to work on a line powered device without being paranoid about safety.
Paranoia runs deep, into your life it will creep!
The sets built in the 240 volt areas used valves (tubes) that had a higher heater voltage at lower current. Many times they added up to more than 120 volts, so they only had to drop less voltage from 240 volts. The mains dropper was a high wattage item and still a common failure item.

Paranoia runs deep, into your life it will creep!
The sets built in the 240 volt areas used valves (tubes) that had a higher heater voltage at lower current. Many times they added up to more than 120 volts, so they only had to drop less voltage from 240 volts. The mains dropper was a high wattage item and still a common failure item.

I've worked on TVs and radios for years just by identifying what prong is connected to the chassis, plugging it into the neutral side of the receptacle, and then lifting the ground on my test quipment to break the ground loop. Never once shocked myself, but I always checked voltage to ground before touching anything. There's no way I'm the only one to do it this way, it is obvious and easy, but only one mistake away from a shock. It's nice to get rid of all that nonsense.

Back in the days when I worked on live chassis equipment I always used an iso tranny as we didn't have earth leakage breakers then (70's). I saw a colleague being electrocuted and unable to let go. Fortunately he eventually threw himself backwards and ripped the mains plug out as he went. He was o/k but very shaken. Could have been much worse. I don't take any chances. Especially when you are working on your own.

Back in the days when I worked on live chassis equipment I always used an iso tranny as we didn't have earth leakage breakers then (70's). I saw a colleague being electrocuted and unable to let go. Fortunately he eventually threw himself backwards and ripped the mains plug out as he went. He was o/k but very shaken. Could have been much worse. I don't take any chances. Especially when you are working on your own.

I think out 120V is substantially less dangerous than your 240, but all the same, I agree about using an isolation transformer. Especially since most line operated devices are switched on the neutral side, so even if you have it hooked up right, the chassis becomes live when you turn it off.

I didn't get to do as much on the Marconi this weekend as I thought I would, but right now the priority is ordering new resistors. I am really surprised how bad the situation is, usually when I work on vintage audio equipment from the same era, the original resistors are mostly fine - but this thing is way out to lunch, some are double the original value, some are half.. it's just all over the place. It "works" as-is, but it's certainly not working as per original design. Considering that over 50% of the ones I have measured are way off, I'm tempted to just change all of them. This will be a lot of work, but I can't see another way to make it work like new.

What kind of resistors to buy as replacements? I'm thinking 1/2W 1% metal films for the majority, and then 2W and 5W metal film for the larger ones as needed. Unfortunately the schematic doesn't give power ratings, so I have to figure them out.

With resistors in older gear I tend to go double the wattage since a 1/2 watt resistor nowadays is about half the physical size of the original 1/2 watt. Metal film resistors seem fine. I know some have concerns about breakdown with high voltages but I've not had any failures (yet).

With resistors in older gear I tend to go double the wattage since a 1/2 watt resistor nowadays is about half the physical size of the original 1/2 watt. Metal film resistors seem fine. I know some have concerns about breakdown with high voltages but I've not had any failures (yet).

I'm changing them out one by one with metal films. I never realized how tedious it is to change resistors and maintain original lead dress... There's just so many of them! Very few are within tolerance, the good ones are 10% off, but some are double in value and even worse.

By saying the resistors are far off, how far off are they? The resistor values are generally not too critical except for some circuits. You may find changing all the resistors a wasted effort if it doesn't make any noticeable difference.

Note most are likely +/-20%. Even outside that it often Doesn't matter. It would be better to focus on the capacitors and only attack the resistors if there is a specific problem.

By saying the resistors are far off, how far off are they? The resistor values are generally not too critical except for some circuits. You may find changing all the resistors a wasted effort if it doesn't make any noticeable difference.

Note most are likely +/-20%. Even outside that it often Doesn't matter. It would be better to focus on the capacitors and only attack the resistors if there is a specific problem.

Most are between 20%-100% off. On average 30-50% high, with cathode resistors reading up to 250% of marked value. This specific TV has the most off resistors I've ever encountered in on TV during a restoration, so I decided to change them all, usually I only replace parts which cause a specific malfunction, as you say.

I usually find the higher value resistors to be the worst offenders. At least you will have peace of mind if you change them all. That chassis came up very clean. It must have been stored in a dry smoke free environment. In Aus back in the seventies a lot of houses had oil heaters. The chassis would be covered in a layer of soot/slime. Very hard to clean.

I usually find the higher value resistors to be the worst offenders. At least you will have peace of mind if you change them all. That chassis came up very clean. It must have been stored in a dry smoke free environment. In Aus back in the seventies a lot of houses had oil heaters. The chassis would be covered in a layer of soot/slime. Very hard to clean.

Yeah this one was full of dust, dead insects and spiders, and strangely sawdust (my guess is it was stored in a garage workshop). I blew it out really well with compressed air, and cleaned all the filthy internal wood surfaces with a rag and a bucket of warm water soapy water. Thank goodness it didn't live in a smoker's house or worse yet a kitchen. Kitchen radios are the worst, impossible to clean grease worked into everything.

Finally got back to this, complete recap save for ceramic or mica capacitors, installed terminal strip for new electrolytics. Cleaned tuner.

Holy smokes, instant gratification... Turned it on and it works almost perfect with only a small tweak of the controls. Bit of snow in the image, probably a weak tuner tube, and the CRT is kind of tired. Going to test all the tubes, and see if I can't make it perfect before it goes back in the cabinet.

"Holy smokes, instant gratification... Turned it on and it works almost perfect with only a small tweak of the controls."

Wao! Izzat cool or what. :banana::banana:

Great result. Don't be afraid to give the CRT a mild rejuvenation. I've found that old B&W CRT's respond well and stay that way for a long time.

I did try to rejuvinate it, and it didn't really do anything for it. It's the original Marconi CRT, so I think it's just tired. It tests in the yellow area, it does make a decent enough picture, but you have to crank up brightness to get it to look nice.

I did most of the work back in May, and have been too busy since then to get back to it. Now that it's working, I need to get the cabinet cleaned up and looking nice. I like the way the top comes off the cabinet, exposing all the working parts. One thing I'm not entirely sure about, is how tight to make the band which holds the CRT to the base board. I don't want to overdo it, for obvious reasons.

I did try to rejuvinate it, and it didn't really do anything for it. It's the original Marconi CRT, so I think it's just tired. It tests in the yellow area, it does make a decent enough picture, but you have to crank up brightness to get it to look nice.

I did most of the work back in May, and have been too busy since then to get back to it. Now that it's working, I need to get the cabinet cleaned up and looking nice. I like the way the top comes off the cabinet, exposing all the working parts. One thing I'm not entirely sure about, is how tight to make the band which holds the CRT to the base board. I don't want to overdo it, for obvious reasons.

Tighten it till there's no wiggle or it is too small of a wiggle for anything to work loose.

Tightening a CRT band always causes tightening of a certain muscle in the body!! Especially when the CRT is mounted on lugs only and the whole weight of the CRT relies on the band.

Yep you've got that right! When I did my 25" Motorola colour tv, I marked the worm gear on the band before I took it apart, and it was much tighter than I would have expected glass to take.

This one is more of a strap holding it down, than a band like newer TVs have. It rests on two mounting points, and the strap goes only on the top and sides. I wish Marconi gave me a torque spec in inch pounds, for the retaining screws. I think it's good now, though.

On another topic, I need to find some tubes for the tuner. I sure can't complain about the price of tubes for this TV, the only semi expensive one is the horizontal output, and I have a few of those in my misc. Junk.

I find it interesting how thick the insulating donut is on that flyback HV winding, and the thick strain relief where the anode lead exits is actually functional. Compared to most of our American built flybacks that one looks very robust. It irritates me how so many NOS flys have a crack right where the anode lead leaves the HV winding. Max, do you know what year your set was made?

http://videokarma.org/attachment.php?attachmentid=197098&d=1526679734

I find it interesting how thick the insulating donut is on that flyback HV winding, and the thick strain relief where the anode lead exits is actually functional. Compared to most of our American built flybacks that one looks very robust. It irritates me how so many NOS flys have a crack right where the anode lead leaves the HV winding. Max, do you know what year your set was made?

http://videokarma.org/attachment.php?attachmentid=197098&d=1526679734

Most of the parts have a 1958 date code, so I believe 1958 or maybe 1959.

Back to this TV after some time, I wanted something to watch the news on while I'm dealing with the COVID quarantine. I turned it on, and now horizontal refuses to lock properly, and the image looks inverted. Hopefully the better techs here will know what this means by looking at the image. Would appreciate any suggestions. Last time I tried the TV it did show a picture properly.

Try turning down the AGC control....If AGC is set too high you will loose sync, get negative video, and sometimes sound issues.

I started it up cold and it synched fine, but then went out of synch again. This chassis does not have an AGC control, surprisingly, although that idea makes a lot of sense.

Tom, you nailed it - a new 3AL5 AGC detector was the cure, it works properly now.

Another issue it seems to have is weak sound. Low volume, and quite a bit of buzz in the audio. The picture looks great now.

Happy to help.

Another issue it seems to have is weak sound. Low volume, and quite a bit of buzz in the audio. The picture looks great now.

Does it use a 6BN6 or series string equivalent? If so the buzz control is the first thing to adjust... Assuming fine tuning knob adjustment can't improve the sound.

Here is the tube layout for the set

I already tried a new 3AL5, and a new 3AU6. I do not have handy a 5U8 to try

Do you have a tube tester or a strong 6U8? Has the low voltage lytic on the detector been replaced in recent years?

Another option if you don't have a tester is to check voltages on the tube if the grid is normal or less negative (/more positive) but the plate is higher than normal that indicates a weak tube (DC plate current below normal).

There's also the lazy audiophool method of turn the set down, plug the audio output of your video source into your stereo and turn the stereo up....I tend to favor this even on sets with good sound.

Set was totally recapped in 2018, but project was put on hold so could be an issue there. Suppose could try a 6GH8 for kicks, have no 5U8. Set is series string, so wouldn't be safe to add an input the 3AV6 is weak, and the pentode section of the 5U8 checks okay. Plenty loud with no signal, but barely anything with either a VCR or modulator.

I will check all the voltages in the sound section to be sure. The plate voltages seem okay.

You get two points today.. a 6GH8 cast off from my CTC38 revived the audio, it is loud and strong now. Will have to find a new 5U8. Thanks again!! This strikes me as odd, because the 5U8 tests only slightly weak on my TV7. For all it will cost I'm thinking to maybe just order a set of new tubes for this TV, it seems like a lot of them are marginal. Interestingly, this set has mostly original tubes, but the 5U8 has been changed already, which indicates to me it might be run hard.

Hey Max, I have lots of NOS 5U8 tubes.

Gregb

Hey Max, I have lots of NOS 5U8 tubes.

Gregb

Hey Greg, good to hear from you.. I will send you a PM