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Old 25th Mar 2010, 10:06 pm   #21
oldticktock
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Default Re: Tv62

Thanks Ed I was still wondering about that, I appreciate your guidance.

Wish I was not such a nervy type, but this feels like a bit of a big jump from radios to TV. Probably should have got more experience under my belt before attempting it. I'm going to let it acclimatise first and in the meantime do some rapid reading on TV's. I will no doubt post back in here when i'm stuck.

Chris.
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Old 25th Mar 2010, 11:35 pm   #22
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Default Re: Tv62

From the Trader sheet, I take it C98 That is the Mains Filter Cap. I notice on the Sheet they don't describe the component function like they do on radios
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Old 26th Mar 2010, 1:02 am   #23
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Default Re: Tv62

Hi old Tick Tock
Tomorrow I am off to visit another member of the forum who does not believe in lamplimiters , but I have found them useful in the past ,
to increase their usefulness , it is worth asking around and getting hold of a few of the very old adapters like my granny would have used to plug her electric iron into the "electric light"
if you build a " christmas tree" you can add extra bulbs and slowly build up the voltage across your radio or television
if you want to be really clever , leave your meter across the output and you can see what the television is getting across its mains
if anybody wants any of the adapters I may be able to help

cheers

Peter
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Old 26th Mar 2010, 8:05 am   #24
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Default Re: Tv62

Peter superb idea, you know I totally forgot about those it's been a while. I think I spotted one in a box somewhere, but if I can't find it I would certainly like one, I will let you know.

Chris
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Old 26th Mar 2010, 8:17 am   #25
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Default Re: Tv62

Hint for working with Trader sheets, especially with TVs which have a lot more caps to change than radios. Since we have PDFs and can print fresh copies we don't mind defacing them. Annoyingly the component values, valve types and pin numbers are not on the main circuit diagram. I often mark up some of the more important bits, especially all the caps that I'm likely to change. Then use a highlighter pen to mark components as you change them.

If you're working on a particularly awkward bit you can print an enlargment of part of a sheet. Well you can with the Foxit viewer, don't know about the Adobe viewer. This makes it easy to mark up voltages, component values etc.
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Old 26th Mar 2010, 9:52 am   #26
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Default Re: Tv62

OTT

As per Jeffrey's suggestion, I found that marking off the items changed as I went was very useful on the first and only TV I've done. Also worth quickly checking continuity from the changed component to the surrounding components against the schematic. It will probably save time later.

Good Luck

Ian
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Old 26th Mar 2010, 10:31 am   #27
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Default Re: Tv62

Quote:
Originally Posted by petertheorgan View Post
Hi old Tick Tock
Tomorrow I am off to visit another member of the forum who does not believe in lamplimiters.Peter
Now I wonder who that can be...........Wimps, the lot a yer..Well I suppose if they calm yer nerves... J.
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Old 26th Mar 2010, 10:34 am   #28
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Default Re: Tv62

Hello,

I'll be following this thread with interest. Your first telly is always daunting I was scared to death of the EHT when I did my first old telly (and even more scared with colour). I ended up pussyfooting quite a lot but next time I think I'll just run it up on a variac (no lamp) and look out for smoke as suggested. After a couple of tingles from the EHT I'm now less worried though it really isn't nice! I still tend to wear goggles when handling the tube....I'm pretty clumsy and scared of flying glass.

One thing to mention though is that you will get some smoke probably from the dropper etc so don't panic this can take a few minutes to burn off.

I'd go with Heatercathodeshort's advice. Replace the two naughty caps and try the set...blanket cap changing is expensive and error prone.

Good luck and keep writing this up!

Dom
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Old 26th Mar 2010, 12:17 pm   #29
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Default Re: Tv62

Quote:
Originally Posted by Ed_Dinning View Post
the EHT, it is the connector on the side of the tube. This is the bit that bites and can store a charge for a long time.
The safe way to handle this is to get an insulated screwdriver and connect it to a croc clip through a length of insulated wire and a 10K resistor.
After the set is off, clip wire to chassis and contact the EHT connector with the insulated screwdriver. You may get a small spark. With the screwdriver still in contact remove the connector.
Ed
To clarify a couple of points

The plug on the side of the CRT is the EHT connector. How does it remove, pull or screw?

The plug on the end of the CRT does this just pull out? , is this likely to hold a charge

Chris

P.s Peter checked my box and no adapter if you have a spare one or know where I can get one it would be great.
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Old 26th Mar 2010, 1:22 pm   #30
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Default Re: Tv62

The EHT connector just pulls out. Best to ease a screwdriver under it to avoid pulling the cable out of the connector. If you connect the screwdriver to the chassis via a clip lead it will also drain any charge which can persist for quite a while after switchoff. The resistor suggested by others is a counsel of perfection. This is an all valve set and won't mind a direct discharge. Be aware that the tube is actually a capacitor, the plates are the graphite coatings on the inside and outside. This can recharge itself due to electrical stresses in the glass. Can give you a nasty nip if you're not expecting it.

The tube socket just pulls off but I would recommend using your thumb against the centre spigot to avoid pulling the bakelite part away from the glass. Alternatively lever gently with a screwdriver between tube base and socket. Any charge here should decay quickly after switch off but you can easily check with a meter.

PS: Don't worry about lamps. Take out the fuse, get the heaters running on the variac. When you're happy with them, connect directly to mains and use the variac to run up the HT as I suggested in an earlier post.
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Old 26th Mar 2010, 1:48 pm   #31
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Default Re: Tv62

OK I connected a croc clip to chassis the other end to the tip of an insulated screwdriver and touched the crt around the white circular EHT plug (see pic one above)... Nothing was expecting a spark, did I touch in the right place?
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Old 26th Mar 2010, 2:16 pm   #32
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Default Re: Tv62

If the set hasn't been switched on in years there will be no charge on the CRT. Even when it is charged you will usually need to dig the screwdriver under the insulating cap to get a spark.
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Old 26th Mar 2010, 2:30 pm   #33
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Default Re: Tv62

OK just wary of digging seems unatural when theres glass involved. The owner said last time it was on was 30 years ago.

The chassis layout regarding some components does not match the Trader sheet pictures.

I think C88 is underneath the paxolin strip it is impossible to get at without desoldering about 12 connections.

C79 can't work out which one it is as the components do not match figure shown. According to the figure its the second cap in from R87 (100k). The first component i see is a cap then a resistor of 100k.
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Old 26th Mar 2010, 2:43 pm   #34
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Default Re: Tv62

The hard men of the forum (Steve P and HKshort) would tell you not to bother even with those caps. Just run it up. It's not as if the valves are scarce and expensive or the transformers fragile and difficult to replace. I'm not a hard man, more a devout coward, and actually ran up my TV80 recently without doing anythng bar clipping out the cap across the mains. Just used a variac. Got light on the screen and sound from the speaker. Then switched off to replace the caps.

The cone of a CRT is pretty tough. You'd need to belt it with a hammer to break it. The neck is more fragile but still more than adequate for the job and doesn't give a big bang if you break it.

NB: This advice on CRTs doesn't apply to some very early types, especially prewar tubes, which can look scary even to tough old engineers. Especially as they're exceedingly expensive and/or difficult to replace.
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Old 26th Mar 2010, 2:56 pm   #35
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Default Re: Tv62

Yes those guys have guts indeed, i'm at the other end of the scale.

Can anyone confirm seeing as how the trader sheet does not state cap function like radio sheets, that C98 is the filter cap 0.05 and not C58 or C77.
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Old 26th Mar 2010, 3:05 pm   #36
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Default Re: Tv62

C98 is the mains filter cap which must be clipped out. From the trader sheet it looks like it's just under the volume control/mains switch. It is likely to be connected directly to the tags of the switch. I'm fairly sure the one you have highlighted is C98 but the photo isn't quite clear enough to be certain.

It's not entirely by chance that C77 "that cap" in the audio amp is close by since one end is connected to the top end of the volume control. C58 is nearby because it is connected to the slider of the brightness control. While C58 will need to be changed in due course it can be left alone for now.
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Old 26th Mar 2010, 3:14 pm   #37
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Default Re: Tv62

Thanks Jeffrey C98 i'm sure is the filter cap, I will snip out, typical though I have about 200+ 0.1uF class X's and not one .047 class X.

I have a 1500v .047 yellow poly would that do?

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Old 26th Mar 2010, 3:32 pm   #38
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Did the meter check across the mains pins resistance measured and when valve pulled continuity lost, so that looks ok
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Old 26th Mar 2010, 4:13 pm   #39
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Default Re: Tv62

100n class X will do fine for the filter cap. The value is totally non-critical. Don't even need to fit a cap at all at this stage. Set will work perfectly well without it.

Good news on the heater chain. Pull the fuse and run it up on the variac. That'll burn the muck off the dropper and warm things up a bit.
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Old 26th Mar 2010, 4:20 pm   #40
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Default Re: Tv62

Excellent regards the filter cap, I did wonder why almost all i've come across were .1, just thought it was tellys

There are two fuses, which one left or right?

Do I just run it up to 150V-180V to warm the dropper?

P.S.
Could'nt help but check what was under the fluff, I was very careful and gentle with a fine artist brush, taking on board what HCS said about disturbing wires etc. Quite amazed at the condition underneath it all.
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