Welcome to Australia's only Vintage Radio and Television discussion forums. You are not logged in. Please log in below, apply for an account or retrieve your password.
Australian Vintage Radio Forums
  Home  ·  About Us  ·  Discussion Forums  ·  Glossary  ·  Outside Links  ·  Policies  ·  Services Directory  ·  Safety Warnings  ·  Tutorials

Tech Talk

Forum home - Go back to Tech talk

 1S2 Rectifier . Flyback windings Insulation Question please
« Back · 1 · 2 · 3 · 4 · 5 · Next »
 Return to top of page · Post #: 1 · Written at 7:15:56 PM on 12 November 2016.
Vintage Pete's avatar
 Location: Albury, NSW
 Member since 1 May 2016
 Member #: 1919
 Postcount: 2048

The wire from my 1S2 Rectifier has lost some insulation where it goes into the flyback windings ,Only where it "joins:" the flyback..I can not see any exposed windings ,It has only lost a small amount. What is a good product I can buy to touch up that Insulation??? The Insulation that's on there appears to be a polly type I think ?? Its bright yellow and hard. The 1S2 tube has blown .But before I go checking why. I would like to get some Insulation on that join.I may have broken the insulation when I pulled the wire off to remove the tube ? I don"t know for sure.

1/ am a Mechanic by trade so I'm still learning to play with wires!
2/ I'm use fault finding with multi meters .been using them for years.

The TV is my 1964 Precedent ..My Baby !!

So if you know whats a good insulating for me to buy , Please let me know.
Ohhhhhh & where to buy it ?? Thanks pete.


 
 Return to top of page · Post #: 2 · Written at 9:17:46 PM on 12 November 2016.
Johnny's avatar
 Location: Hobart, TAS
 Member since 31 July 2016
 Member #: 1959
 Postcount: 543

Just solder the wire on, and make sure the joint is a nice round blob(no sharp edges).
Then coat with clear fingernail polish and let dry.
Normally these situations rely on air insulation, so lead dress is important.
In over 50.000 repairs years ago have not had a 1S2 "blown".The very odd o/c filament, yes.
But they do go weak, and show up as poor regulation.(dark in centre of screen varying with brightness level).
JJ


 
 Return to top of page · Post #: 3 · Written at 10:39:39 PM on 12 November 2016.
Vintage Pete's avatar
 Location: Albury, NSW
 Member since 1 May 2016
 Member #: 1919
 Postcount: 2048

Hello John.....>>>>>>>>>thanks That makes sense to me as nail polish is what I would use if rotor button and distributor cap were leaking in a car and after fixing 50k TVs you would know how to insulate that area ,,,,Thank You all the best , Pete.


 
 Return to top of page · Post #: 4 · Written at 2:45:50 PM on 14 November 2016.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 2363

Hi Pete

I'd ask the same question - what makes you think the 1S2 is "blown"? It would be very unusual. Any fault in the line stage can stop the 1S2 from being lit. Normally the only time you ever look at the 1S2 heater loop is when it breaks down - sizzles or large noisy sparking happens. If you aren't getting that, don't touch it, it's not your problem.

When I was a kid I worked in a local radio and TV shop. The owner sold stacks of 1S2s to DIY types who'd arrive at the shop assuming that because it didn't light up the 1S2 needed to be replaced. They would invariably come back asking for a refund for the new valve that was faulty!

Now if you really need to replace the loop......

Careful - many 1S2 heater loops used resistive wire. If you use normal wire the heater will be overdriven and will wear out quickly.
If there is a 1.5 ohm resistor inside the socket in series with the loop then you need normal copper wire.

That special resistive EHT wire is unobtainable. I use the insulated core from solid core (not stranded) RG59 co-ax. Then cover it with at least two layers of heatshrink. If there is no 1.5 ohm series resistor I fit one. There may also be a resistor of about 1k ohms in series with the EHT cable to the CRT, don't confuse this with that in series with the heater pins.

I guess you could use solid core ignition wire but it's a bit thick.

You can't measure the 1S2's heater voltage directly. The way it's done is to compare the glow colour with another 1S2 with 1.5v DC on its heater pins. It should be a dull orange. It's also important to avoid any sharp points on anything when soldering, they will create a corona discharge which will eventually punch through the socket insulation. Treat it like spark plug wiring! EHT is 17.5kV on that TV, enough to jump at least 20mm and give you a nasty jolt.


 
 Return to top of page · Post #: 5 · Written at 2:59:59 PM on 14 November 2016.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 2363

Just re-reading your first post, I think we may have misunderstood.

I think you are talking about the wire from the line transformer (US term "Flyback") overwind to the 1S2 top cap. The overwind is the bit that looks like a little wheel.

The original insulation was wax. You could use ordinary candle wax to repair it, carefully. Silicon sealer also works BUT IT MUST BE NEUTRAL CURE!
Smell it first, If it smells like vinegar DON'T LET IT NEAR ANYTHING ELECTRICAL!

My comments about the 1S2 not being the fault still apply! If it has been running and has just stopped there is a well-tried fault finding procedure I could run through with you. Let me know.


 
 Return to top of page · Post #: 6 · Written at 3:20:34 PM on 14 November 2016.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 2363

I've just had a look under the chassis and I think I know where your fault is.

If the set was working and just died, it's most likely the B+boost capacitor has failed. It's the white tubular one near where the red EHT cable emerges. They work hard and normally fail soon after the set is fired up from a long period of hibernation.

If it has "UCC Hi-Qual 100" or similar on it, then I'd put money on that being your fault. If it says "Di-Pol 100" or similar then it's far less likely to be bad.

If it's a "Hi-Qual" it's a paper cap (dressed to look like a polyester) and it needs to be replaced unconditionally with at least a 630 volt rated modern part.

Back then, when the modern polyester dielectric capacitors became available, engineers were still worried about using them in a position where the capacitor had to handle high currents. So they'd spec a paper cap for that position. Time would show their concern wasn't justified.

Ian


 
 Return to top of page · Post #: 7 · Written at 3:46:23 PM on 14 November 2016.
Vintage Pete's avatar
 Location: Albury, NSW
 Member since 1 May 2016
 Member #: 1919
 Postcount: 2048

Hello Ian , Thank you. I was hoping you might spot me waving a flag,hahah Ok what happen was this ,The TV was working ,But when I switch it off a white dot stayed in the center of the picture tube for about 5 secs , I found that if ,I was to switch the TV on and off at the Knob again it stopped it happening,,So I took the back off the TV to look inside and I noticed that when TV is turned on there was Zero Glow from 1S2 ?? So I had a spare 1S2 and I unpluged the TV from the Mains and then And the proceeded to remove that 1S2 from its socket ,When I removed it ,I noticed thats its Hat was loose and no longer bonded to the Valve , So I replaced the 1S2 with a spare I had , In doing so I may have broken some of the insulaution off the wire where joins onto the Windings """""Eg Yellow Wheel"" So I put a small amount of silicon over the damage area which was very small and no wires where showing,,,,So After it dried and with a new 1S2 installed , I plugged it back into the mains and turned it on ,,,.. 1S2 was Glowing again and when I turned the set off there was No white Dot in the center of the picture tube and I thought Hmmm Well its fixed ! But it was short lived as the 1S2 has stopped Glowing again,,,,,,,,,Thats where its up too now , I have not looked at it again because I need to buy a new Multi meter on Thusday first '

Ian, I'm only learning ,But please note I take all care when learning about TV's and electonics , I do all my repairs on a wooden floor and a 2 in Rubber mat .My Wife is a Electrical Engineer ,"""" Pen Pusher """ She has never had hands on tools and at the moment she is over seas , she doesn"t know how valves work .. Never touched one ! hahahah, But she chats to my about Theory so I'm learning as much as I can .
>>>>>>>>>>>>>>>>>>>>>>>>>>>Thanks Pete.


 
 Return to top of page · Post #: 8 · Written at 3:51:07 PM on 14 November 2016.
Johnny's avatar
 Location: Hobart, TAS
 Member since 31 July 2016
 Member #: 1959
 Postcount: 543

Sounds like you need to resolder the filament loop.


 
 Return to top of page · Post #: 9 · Written at 4:01:36 PM on 14 November 2016.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 2363

Yes it still sounds like it could be the B+boost cap.

Reason for the spot is most likely an open circuit aquadag ground. The aquadag is the black coating on the back of the CRT. It should have a spring loaded wire that runs across the dag and connects it to the frame.

Another reason:

If you turn off the TV before the CRT has had time to fully warm up you will usually get a white spot, because the CRT can't yet draw enough beam current to discharge the EHT on switch-off. Or if the CRT is low emission, i.e. getting towards the end of its life. I hope it's not that!


 
 Return to top of page · Post #: 10 · Written at 4:12:32 PM on 14 November 2016.
Vintage Pete's avatar
 Location: Albury, NSW
 Member since 1 May 2016
 Member #: 1919
 Postcount: 2048

Ian !! You hit the Nail on the head !! I Remember that the Ground spring wire from the CrT too the swinging Chassis door was loose and I fixed it !! So I guess thats the problem. On Thursday night I will work on it again and let you know how I go ,,I really dont believe there is much wrong with it another than teething problems ,,,Thanks again Ian !!!!!!!! >>>>>>>>>>>>>>>pete


 
 Return to top of page · Post #: 11 · Written at 4:14:39 PM on 14 November 2016.
Vintage Pete's avatar
 Location: Albury, NSW
 Member since 1 May 2016
 Member #: 1919
 Postcount: 2048

Hi John Thank you,,,,,I will check it on Thursday and re-solder it , Thank you for your help with my old telly >>>>>pete


 
 Return to top of page · Post #: 12 · Written at 4:26:13 PM on 14 November 2016.
Vintage Pete's avatar
 Location: Albury, NSW
 Member since 1 May 2016
 Member #: 1919
 Postcount: 2048

The Cap Is a Poly >>>> "Di-Pol 100" I can see that cap


 
 Return to top of page · Post #: 13 · Written at 5:21:31 PM on 14 November 2016.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 2363

It still could be the boost cap, tho less likely.

Quick check procedure:

1. Hold a well-insulated screwdriver close to the 6CM5 top cap. You should be able to draw an arc about 5mm long.
2. If no arc at all, check voltage on pin 5 (G1) of 6CM5. It should be at least 30 volts negative.
3. If not, Horizontal Oscillator is not running. Don't run the set for more than 60 seconds in this mode, you'll cook the 6CM5. Go to item (6).
4. If you get a very weak spark from the 6CM5 top cap, try replacing the 6CM5 and 6AL3 although given the failure nature this is unlikely. Change the B+boost cap.
5. If this doesn't fix it, check the horizontal output transformer winding for temperature rise. If detected, you have a shorted turn in the transformer. Bad news.
6. Intermittent no-start-up of the horizontal oscillator is usually caused by an intermittent open circuit cap across the oscillator coil. That coil is the one with the plastic adjustment stalk - I can see a white-labelled styro in the pics. You must replace it with a styro or mica cap, a polyester cap will cause the oscillator to go off frequency with temperature.


 
 Return to top of page · Post #: 14 · Written at 7:44:12 PM on 14 November 2016.
Vintage Pete's avatar
 Location: Albury, NSW
 Member since 1 May 2016
 Member #: 1919
 Postcount: 2048

Thanks Ian , I can understand that ,Thats nice and clear ,,I will work on it on thursday night ,,Thank you for all your help, Its been good fun too !


 
 Return to top of page · Post #: 15 · Written at 4:28:36 PM on 18 November 2016.
Vintage Pete's avatar
 Location: Albury, NSW
 Member since 1 May 2016
 Member #: 1919
 Postcount: 2048

Hello Ian & John ,,, Just an update of where I'm up too,,,,,,I bought a new Multimeter on Thursday and a Good Quality 1000 volt Screwdriver to perform the test. But I decided to start at the Beginning first and Replace the main power leads to the TV, Radio and Record player before I started to work on the set , They looked a bit Ugly in a couple of spots and as I pulled out the Radio chassis I saw the Neutral wire under the Control switches had perished insulation and was sitting on ground. So I have re-wired all the mains to the 3 Units and put new fuses in.

So now that I know that the mains are all good and Earths etc etc, have all been checked, I will continue to work on it on Saturday night. So I will have more to tell you by then.

Thanks for your help with my TV ..I really appreciate your help and I have learnt a lot and enjoyed doing so.
>>>>>>>>pete


 
« Back · 1 · 2 · 3 · 4 · 5 · Next »
 You need to be a member to post comments on this forum.

Sign In

Username:
Password:
 Keep me logged in.
Do not tick box on a computer with public access.