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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Aug Mon 12, 2019 4:40 am 
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When I have to repair circuit card traces like that, I generally clean the solder flux off and then strengthen the repair with epoxy glue. Alcohol and a Q tip will clean off rosin from rosin core solder.

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Aug Mon 12, 2019 6:11 am 
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Thanks Tom. Do you often recreate the trace with new solder on the board itself (Clean Old > Apply Epoxy > Apply Flux? > Apply New Solder Line?) instead of a wire bridge?

I actually did go shopping for epoxy and super glue today thinking at least to better adhere some of the solder joints to the PCB, but there are so many varieties I became overwhelmed. I know they sell specialized PCB repair epoxy type materials online but it is quite expensive. At my local home store there are about three dozen variants of epoxy including multipurpose, instant-mix, plastic bonder, quick-set, plastic welder, self-mixing... Some included a brush. Assuming I can get this TV back to a working unit again I may revisit this part to do a more thorough clean-up and redo of these solder points.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Aug Mon 12, 2019 3:01 pm 
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Location: Dallas, TX
The best way to repair circuit boards is to solder wire or copper foil to exiting circuit traces. I almost never try to glue things down unless the missing section is used for the support of a component. The multipurpose epoxy would be as good as any. Superglue is wimpy when it come to high temperature (you might have to replace a part nearby in the future). You may not know how circuit boards are made, the foil is bonded to the board material in a high temperature press that finished the cure of the board material under pressure. It is not glued down. Even epoxy is barely able to stand solder temperature.

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Aug Mon 12, 2019 4:44 pm 
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The old horizontal shaft is supposed to be flimsy since it is a user adjustment you want it to have flex so if a kid Yanks on the end they won't break the delicate hold coil. The adjustment screw should be turn very easily so the spring can turn it. If it doesn't turn easy it may need a drop of light oil.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Aug Mon 12, 2019 5:23 pm 
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I just add a thin wire to bridge the gap. I just use ordinary general purpose epoxy. I tend to avoid the 5 minute epoxy as I don't think that it is as strong as the regular epoxy.

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Aug Tue 13, 2019 5:25 am 
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Quote:
If it doesn't turn easy it may need a drop of light oil.


Excellent! It was stubburn to turn initially, even when using a mini-flat screwdriver. I struggled to keep the spring attached even after iI had clamped it once to try and strengthen the hold. I applied a small amount of oil (WD-40, which I know may not be ideal but was all I had on hand) and now the screw turns very nicely both ways and the spring remains attached.

My replacement flyback arrived today and while I have not worked at it yet, it appears to be in excellent condition including the necessary wires and end cap already in place and properly wound. The coating is more of a wax material this time instead of the hard and easily cracked plastic from the original one. I look forward to getting this component swapped (after many months!)

QUESTION: Is there any standard technique for how to prop up a picture tube when testing so it doesn't and up tilting and busting the neck? I will obviously want to test (and continue recapping) while it is out of the cabinet, but it seems difficult to get the picture tube to sit nicely on a table without it tipping over. I was going to construct a small wooden or foam brace with a hole/cutout for the neck that it could rest in, but am thinking there may be a better option.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Aug Tue 13, 2019 6:32 am 
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shops used a test crt for bench testing a set. i have one here and will check the tube number later when i have time. it is awkward to prop up a large crt on your bench. if this is one of the tvs that has the crt mounted in the cabinet instead of on the chassis you could also make up extention cables to hook up the tv to the crt in the cabinet.

i am glad the flyback looks good and appears to be the correct one. the wax can melt or crack over time from the heat in the set. early plastics really sucked though. they all seem to be brittle and cracking now. the cover for the yoke in some sets was plastic and they are deteriorating badly now. when soldering in the flyback make sure all solder joints are as smoth as possible as any sharp points can cause arcing.

8xp4 is the test crt i have for use with sets that have a rectangular crt. i dont remember the number of the test crt used with round crt. i no longer have one of those.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Aug Tue 13, 2019 7:33 am 
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Here is a scan from the cabinet insert: "To check picture in shop, use proper picture tube or universal type 5AXP4."

Researching a bit, that seems to have been a very common tube in shops but is now difficult to obtain. The 8XP4 appears to had been a close relative and sold alongside it for similar purposes. From the sheet for the 8XP4 (found on eBay albeit sellers are asking $100+ for it there):

Quote:
An additional universal test picture tube, type 5AXP4, is also available. This is a round, 5-inch tube, with advantages similar to the 8XP4 except that the deflection angle of the 5AXP4 is 53' compared to 90' for the 8XP4. Either test tube will operate satisfactorily for testing purposes in 53, 70 or 90 degree deflection systems. However, for greatest benefits it will be found convenient to have both tubes available. The 5" round 5AXP4 for 53' and 70' receivers; and the 8" rectangular 8XP4 for receivers employing 90' deflection.


In this television the tube is mounted into the cabinet completely separate from the chassis. I feel it would be difficult to make extensions to it especially in how I would get the anode lead to it. As I have both the original tube (barely functioning but was originally able to still get dim static on w/ brightener) and a NOS tube, I am not opposed to still trying the old tube if I can find a good way to brace it while working at it.

This got me to look at the yoke on the old tube... It seems quite dire itself (the plastic ring detached etc) although was still seemingly operational before these unrelated issues arose. For future reference in case I need to find a new one, SAMs notes the part as: Admiral 94D87-10, alldorson DF607, Merit MDF-92, RCA 235D1, Ram Y90F19/43, Stancor DY-16, Thordarson Y-16, Triad Y-41-1.


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1565675931132 (Custom).JPEG
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Admiral Chassis Removal Warning (From Case) (Custom).jpg
Admiral Chassis Removal Warning (From Case) (Custom).jpg [ 229.59 KiB | Viewed 672 times ]
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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Aug Tue 13, 2019 8:23 am 
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Posts: 591
Location: Belrose, NSW, Australia
That plastic degrading is quite common with yokes of that vintage, it seems to be related to exposure to ozone from the HV connection.

I use a round polyethylene food storage container with a screw lid and contact adhesive, like in these pics.

Attachment:
Yoke 1.JPG
Yoke 1.JPG [ 142.07 KiB | Viewed 671 times ]


Attachment:
Yoke 2.JPG
Yoke 2.JPG [ 155.89 KiB | Viewed 671 times ]


Cut the bottom out of the container to clear the "waist" and make a cut in the side so you can flex it and clip it around the waist. Add glue, let it set.

Extension cables are necessary for working on that set. Yoke and CRT cables are easy enough, I made an extension HV cable from a dead tripler from a colour set, a clip-on lid food container, a plastic bottle cap, a washer and hot-melt glue. If you can't visualise that, I'll take a picture and send it to you.

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Aug Tue 13, 2019 3:09 pm 
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To make a CRT cable extender get a brightener that fits that CRT remove the step up transformer and extend the leads. Octal bases for the yoke are easy to get. IIRC you can get lengths of raw sparkplug wire at auto parts store that should work for the HV lead...just sitck the connection to the stock lead into a glass jar or cup so it can't arc to anything and get a clip for connecting it to the CRT.

If you can get an 8XP4 it should work. I have a Telematic test kit with an 8XP4 (or was it an AXP?) And I have used that CRT as a test tube in sets that you are supposed to use a 5AXP4 as the test CRT...it will work but you will have a small round image. The 8" tube has a wider Deflection angle than the set so the set can't paint the corners. You can work out all but the final adjustments that way.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Aug Tue 13, 2019 4:30 pm 
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Location: Dallas, TX
I think that making extension cables would be much easier (and cheaper) to do than to find a test CRT. You only need to make the cables a couple of feet long, don't plan on spanning across the room.
If you go the spark plug wire route be aware that some of that wire is made to have resistance because that cuts down on radio interference.
Crist Rigotti on this forum posted once about his making a new flyback cover using thin aircraft plywood and some PVC pipe. It looked near original.
Be care handling the CRT. Depending on where a crack would start the CRT could implode sending shards of glass all over the room. It is a good idea to wear goggles.

EDIT: I found Crist's thread containing how he built a new yoke cover. He does great work and goes that extra mile.
viewtopic.php?f=3&t=321038&hilit=yoke&start=60

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Aug Wed 14, 2019 12:50 am 
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I checked with a local auto shop and they have by-the-foot spark plug wiring but the only kind in stock is tinned metallic core instead of copper. Anyone have experience using metallic core for anode lead? I do see I can find some copper core by-the-foot spark plug wiring on eBay as well. Alternatively I know some use neon wiring rated for 15K; would that be reasonably safe (the tube specs indicate 14,000 volts but the tube may operate at voltages as high as 19.8K).

I'm thinking that perhaps I should just move the chassis back into the case for the first time testing once I get the new flyback on to see if I can at least get some tube signal again as it was initially. The extension route still seems quite a process when the chassis does sit quite easily in the back of the cabinet with the CRT still connected.

Quote:
EDIT: I found Crist's thread containing how he built a new yoke cover. He does great work and goes that extra mile.


What an amazing restore!


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Aug Wed 14, 2019 1:43 am 
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Location: Arlington, TX, USA
Someone correct me if I'm wrong, but I believe the HV anode current in most sets isn't much more than 1mA at most, so the voltage drop will be measured in tens of volts using resistance spark plug lead; not much compared to 10-15 KV, so it should work.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Aug Wed 14, 2019 2:06 am 
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Location: Woodinville, WA USA
Re connecting the CRT, in some TVs you can stand the chassis behind the cabinet and connect everything with the native cables:

Image

That's not possible with every TV, but it does eliminate the need for extender cables or test CRTs.

These articles have more info about the 5AXP4 and 8XP4 test tubes, if you want to go that route:

https://antiqueradio.org/5AXP4PictureTube.htm

https://antiqueradio.org/8XP4PictureTube.htm

Regards,

Phil Nelson
Phil's Old Radios
https://antiqueradio.org/index.html


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Aug Wed 14, 2019 4:37 am 
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Location: Dallas, TX
MattPilz wrote:
I checked with a local auto shop and they have by-the-foot spark plug wiring but the only kind in stock is tinned metallic core instead of copper.


I'm not sure what "tinned metallic core" is but it doesn't sound too bad. Maybe the core is steel or aluminum.
It could work, as was said the current is low.
I thought since I think you said the original CRT had a brightener you could use that as a source for the CRT socket cable. If the yoke connector is an octal it isn't very difficult to get plugs (tube base) and sockets.
You would just have to connect the cables one-to-one ( pin 1 to pin 1, pin 2 to pin 2, pin 3 to pin 3, etc.).

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Aug Wed 14, 2019 9:53 am 
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matt you bought a nos 2nd anode lead which is the wire to the crt you are trying to extend. that wire would be perfect for your extention cable. nothing better than the wire origionallly used for the purpose. you would just have to connect the 2nd anode lead from the set to the new wire. the other end of the wire allready would have the connection to the crt on it. if you do make extention cables keep them when the job is done incase they are needed in the future.

if ur going to do allot of tv repair it is well worth it to invest in the 8xp4 test crt. if this is the only tv you are going to work on maybe not so much. the easiest way to bench test a tv is with a test crt eliminating the need to have a bulky cabinet and large fragle crt anywhere near ur bench.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Aug Thu 15, 2019 1:06 am 
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Quote:
you would just have to connect the 2nd anode lead from the set to the new wire.


The new wire/lead is longer than I expected, about 19" versus the original that is 7". Just that on its own would probably give me enough distance to connect to the CRT directly without having to slide everything back into the cabinet. If I did have to extend it I'm not quite sure how I would go about connecting the lead end of the existing to the wire of the new. The existing lead is barely attached to the old solder anymore so I think no matter what I will end up replacing that with the replacement one I got.

Here are photos of the different connectors. The deflection yoke has already been through some work in the past it seems, as all of the wires were spliced back together.

QUESTION: The two wires that loop around the flyback and attach to the HV Rect tube pins 2-4 ("Anode Lead Connection" photo attached) ... Can either end be attached to either pin? According to the tube pin layout (1B3GT) 2 = Filament and 4 = No Connection. Should the resistor in there still be acceptable or worth replacing?

At some point I may simply try moving the chassis near the cabinet to see how much room I'd have to work with. If I could manage something similar to @philsoldradios photo that would be decent.


Attachments:
Socket to Tube - 1.JPEG
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Socket to Tube - 2.JPEG
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Yoke End.JPEG
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Brightener - 1.JPEG
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Brightener - 2.JPEG
Brightener - 2.JPEG [ 176.7 KiB | Viewed 601 times ]
New Anode Lead.JPEG
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Anode Lead Connection.JPEG
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Anode Lead End.JPEG
Anode Lead End.JPEG [ 155.65 KiB | Viewed 601 times ]
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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Aug Thu 15, 2019 3:21 pm 
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First, it does not matter which of the filament pins connect to which end of the wire around the flyback. While you are working on it I would replace the resistor, but you could measure the resistor and see if it is within tolerance and keep the old one. In case you don't realize it they used an unconnected pin on the H.V. rectifier socket for a tie point.
The yoke socket has more pins than I thought (11), I have seen as few as 5 pins on a yoke connector. Eleven pin connectors were (are ) used on plug-in relays, so the sockets are not that hard to find. I don't think many tubes had 11 pins of that size.

You could just use a small alligator clip on the other end of the anode extension wire.

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Aug Thu 15, 2019 4:49 pm 
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If you are.replaci g the HV lead to the CRT just remove the old and solder in the new. If you plan to keep the old lead and simply want to add a temporary extention take the end lead and securely wrap the ends together and stuff the bare section of wire in a glass cup or jar so it can't arc...if the wrap method bothers you you could make a light tack solder instead.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Aug Sun 18, 2019 12:04 pm 
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An amazing weekend milestone update!

Flyback: To start, I replaced the busted flyback with the "exact fit" Merit HVO-145. The only difference I noticed in the schematic was the HV Rect resistor for the replacement is "4.7Ω 5%" while the original is "5.1Ω 5%" - it is still within the tolerance window. I checked the resistor with a multimeter and the resistance was still precise so I reused it; I had no other comparable one on hand.

Anode Lead: Then, since the original anode lead wiring seemed loose and I was already working at the HV Rect for the flyback, I took that off and put the replacement Anode lead (40K rating) in its place. Unfortunately, I realized that the rubber tip of it was too rigid/bouyant to stay adhered to the tube. The prongs would pop out instantly no matter what way I tried to insert it. I wound up splicing the new wire onto the old so that I could still use the original cap, which fits very securely to the CRT. I currently have the splice point wrapped only in 600V heat shrink, but afterward stumbled across some NOS "High Voltage Splice for CRT Anode Leads" on eBay made specifically for this type of extension (Moyer Electronics has some too). Once I get that I will redo the anode lead splice with this so the entire lead will be 40K protected.

Vacuum Tubes: Over the past four months I've been accumulating replacement NOS tubes that have already been fully tested, since I still lack a tube tester and these were all reasonably priced. Knowing that some of mine were potentially damaged from the bad horiz. coil and flyback I went ahead and swapped all of them. I kept the originals as I suspect many are also perfectly fine, so will have spares and can test them in the future. Every tube on the chassis has been replaced. I often read this is an unnecessary step but I was able to get most of them from a single seller who tested each and wrote the values immediately prior to shipping.

Chassis to CRT: After some experimentation, I concluded that by extending the anode lead (as I already had by splicing the original to new) as well as adding about 6-8" to the yoke wires, I could manage to connect everything by propping it up behind the cabinet as others have demonstrated. So I extended the yoke wiring (with 105' 600V). I found that a computer tower was perfectly aligned with the bottom of the cabinet and of proper width to support the chassis so that is what I used. In this manner I was able to get everything hooked up to the original CRT without having to feed everything back through the cabinet or risk damaging the neck of the CRT. The extensions on the yoke and anode lead are permanent.

Powering It Up: It had been more than four months since I last powered it on. I have replaced a few electrolytics, the flyback, horizontal oscillator and vacuum tubes. I fed everything to a Kill-A-Watt to monitor it as I powered it up. After some experimenting I managed to get an actual picture to come through via DVD player! I found that there seemed to not be any difference with or without the brightener now and I am able to see the picture quite well even with lights on. I have verified that the channel selector / fine-tune, power and volume, brightness and vertical hold controls all are functional. I'm actually completely impressed that everything is kind of functioning decently even with the old tube.

VIDEO: https://www.youtube.com/watch?v=J8f9n30-bZ8

And now for the new line of questions/observations...

Arcing: I did not see or detect any arcing from the repairs I made including some very basic checks around the flyback area with an insulated screwdriver, at least nothing happened when I was an inch or so away from any metal/solder joints, but I didn't want to get carried away testing. However, I do hear electrical "crackling" from the flyback that sounds like electricity moving about or generating, and am not sure if it's normal to audibly hear noises from the flyback or if that means there is stray electricity somewhere? I can hear this from a foot or two away.

Voltage: The values I got from the Kill-A-Watt include: Volts - 121.5, Amp: 1.73 Watt: 200 VA: 211 - Does this seem within an acceptable range? The SAMs schematic lists the PSU rating as: l.52 Amp. @ 117 Volts AC

Chopped Off Bottom Image: As the TV warms up, the bottom of the image gets increasingly chopped off until soon a couple inches or so at bottom is just a straight cut off where the picture once was. When I first turn it on the picture fills the screen. No adjustments seem able to fix this once it happens. This was something I noticed originally when I first turned it on in April. Moving the yoke still retains that same chopped off black section regardless of image size, and it happens with or without the brightener.

Ghosting: The actual image is very badly ghosted. Is this just a likely issue with the age of the tube that the replacement one I have will resolve?

Vertical Stretching: Vertically there are some definite squishing/stretching issues going on. Human heads all tend to look like a cone head as the screen stretches from the center to top, while the lower half is squished giving people very short legs. Any advice on how to properly collaborate this, is it a spin-off from the issue described above with the bottom getting chopped off?

Brightness: Someone once mentioned that if I turn the brightness to max it should be a fully white screen with no picture, but with mine even at max it still shows the picture clearly. Could this just be due to the fact that the picture tube is so worn?

All of that aside, this seems like it was a pretty decent and successful update right?


Attachments:
1566125888790.JPEG
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File comment: The small clone of the head in top-left is actually a reflection from a mirror I was using to test, not internal artifacts.
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1566125888647.JPEG
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Untitled-2.jpg
Untitled-2.jpg [ 199.55 KiB | Viewed 509 times ]
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