what or how to check CRT HV anode wire repair ?

Turn it on in a dark room and look for corona, smell for ozone, listen for sizzling, and pull the plug if anything bursts into flames :)

Ahhh!!! why deny us the pleasure of a nice bonfire????? (have a video capable phone ready please!)

"robb" wrote in news: snipped-for-privacy@corp.supernews.com:

I'd allow a sufficient time for the silicone to cure FULLY. Otherwise,it becomes a leakage path.

Better to wait too long than too little.

the

Hello Jim,

Thanks for help.

I created a mock up cap and silicon seal on a piece of glass just after the repair cap and seal so that i could check in 24 hours to see where the mock up was in the curring cycle.

I was planning to wait 24 hours, check the mock up curring and then see if i should wait another 24.

Thanks for the help , robb

the

listen for

Haha.... I may eat my soldering iron if it bursts into flames. (after it cools down... the soldering iron that is)

thanks, i think, robb

the

ozone, listen for

Ok, so i will start he video camera before i turn it on the next uTube hit :{ robb robb

An AM radio nearby can give a good indication of corona discharge. You get a sort of a 'whining' noise. Breathing on the area with a good "HAAAAA" will also show up any tendency for corona, which takes place more readily when the air surrounding any potential discharge site, is made moist. With the AM radio on, wave a screwdriver around the area. Again, this will provoke any potential sites, and you should hear it. Eveness of the outer 'dag coating should not be of any consequence.

Arfa

discharge. You get a

"HAAAAA" will

readily when

moist.

Hello Arfa,

Thanks for reply.

Breathing with a HAAAAA ? is this going to be one of those the HAAHAHA, the jokes on me kinda of suggestions ? where my ears buzz, i see flashes of light and my eyebrow twitches for the rest of the day. :)

Sounds suspiciously like one of those suggestions the Senior engineers give to the new rookies to amuse themselves and the other senior engineers.

provoke any

'dag coating

as long as it does not provoke a zap on me then i will give it a try.

Thanks for the help Arfa, robb

No, it's quite genuine. You need to "HAAAA" like a giant sigh, rather than blow like putting out a candle. This shifts a large volume of slow-moving and moist air into the area. Any spikes on the soldering or poor insulation on the HV, will discharge much more readily into moist air, than dry air. It represents no danger to you, as nothing is going to jump that distance, unless your 'scope tube has a PDA with about a 100kV on it ...

The metal shaft of a screwdriver with a plastic handle, held in your hand, will draw a good arc from a high voltage supply, without you feeling a thing. In the good old days of valve (tube) only TV sets, it was a standard test to pull an arc from the top caps of the boost rectifier and HOP valves. Also, from the cap of a DY87 or the wires of an EY86 HV rectifier valve. You couldn't do it in later sets, because of those new-fangled transistor things, that would just expire if did anything like that within about 2 yards of them ! Anyway, the point is that if there is anywhere that has a predisposition to corona discharge, a metal screwdriver blade waved in the vicinity, will likely help it along. I'm not talking a big long spark jumping out at you, just some ozone, or maybe a discharge that you can hear.

Trust me ! No dangerous suggestions from this quarter, ever ...

Arfa

Related: Check your car's high tension (spark plug) wires. On a dark night, away from ambient light; open the hood with engine running. Leaky HT wires will be readily apparent.

I had an AH Sprite that 'accidentally' introduced me to this technique, which I've seen published since. I opened the hood for some reason...blue sparks were dancing all over the engine. I replaced all the HT leads toute suite....

jak

This reminds me of an incident many years ago in a TV repair shop. Several of the engineers had been feeding a mouse and it had become quite tame, running down the back of the benchtop. Anyway one day someone managed to zap it with a loose anode cap lead. I'de never seen a mouse glow blue before.

Silicon cured, CRT installed and tested.

Sorry no fireworks or shooting flames :D

thanks to Arfa, Jim, James, Sjouke etc...for the help.

Installed the new CRT and watched for all the symptoms and signs people mentioned in the (sci.electronic.$$$$$) groups

No HV problems. But now the scope needs display adjusting to suit the new CRT.

Problems: ========== The display is skewed and the intensity and focus are off.

I was not expecting te new CRT to have hyper-intensity troubles. That is... from no visible trace to oversaturated CRT brightness is a very small range of knob motion maybe a 1/4-1/3 of he full turn .

And the focus is very sensitive, touch sensitive ? was not before.

And the internal probe calibration signal (.5 V @ 1 kHz) produces a trace with fuzzy band for peaks ( 20 - 30 mV) or so wide. This was not the case before maybe more like (5 mV ripple before CRT swap)

So hopefully i can sort these problems out.

thanks for all the safety advice, robb

"robb" wrote in news: snipped-for-privacy@corp.supernews.com:

It needs a complete calibration,not just a "display" adjust. Adjusting vertical and horizontal gains affects freq.response.

trace rotation,geometry and astigmatism adjusts.

That doesn't sound very good. That CRT may NOT be a usable replacement.

What model scope,and what CRT part numbers,old and new?

It sounds to me like this replacement CRT might not be quite as 'compatible' as you had hoped ... :-( Maybe that's part of the reason that the PDA lead was not long enough to fit in your chassis i.e. to stop such a substitution taking place. As far as the trace being 'skewed' do you mean that it is not perfectly horizontal, or that it is trapezoidally distorted ? If the former, then most decent 'scopes have a trace rotation control somewhere. As far as the brightness / focus issues go, that is likely to be quite difficult to resolve, and will probably require changes to be made to the component values in the resistor chains providing the biasing voltages to the various electrodes. I would suggest that you will not get too far with that, without having schematics for both the 'scope that you've put the tube in, and the one that it came out of, so that you can make comparisons of values and expected voltages. Just as a matter of interest, are the quoted deflection sensitivities for both tubes the same ?

Good luck with it - I think you'ree going to need it, but it's nice to see that a sense of experimentation still exists out there - it's the sort of thing that I would have been playing with 30 years ago ...

Arfa

troubles.

brightness

full

'compatible'

the PDA lead

substitution

that it is not

If the former,

somewhere. As far as

difficult to

component

the various

that, without

in, and the

values and

deflection

nice to see

the sort of

Hello Arfa, It is a Tek scope. There are lots of pots for adjusting the CRT params.

The CRT was replaced with its **reverse** compatible replacement P/N.

That is, typically one replaces the earlier model CRT with the newer model and i have done the reverse. I replaced the newer model with the earlier model. Unless it was a "one way compatibility" then technically it should work.

The HV lead was longer in newer models because of physical change to the Flyback/HV multiplier transformer and orientation. The earlier model machines had an HV Jack on an 3" HV lead coming off the Flyback the newer models have te HV Jack on the Flyback directly.

So you need just 1" (2.5 cm) more HV lead to make it there.

Hopefully i can cure problems with the adjustments, as I do not really want to modify the original PCB /schematic values.

Thanks for help and ideas Arfa, robb

Hmmmm. Sometimes, compatible substitution *is* a one-way street. If the parameters of the two tubes were sufficiently similar, I would not have expected there to be a huge difference in the external setups, or for the operation of the user controls to become 'bunched' as you described. There are a couple of Tek 'scope experts who pop up on here from time to time who would be much better qualified to advise you on the specifics of your problems than I, so hopefully one of them will dive in to help you shortly !

Arfa

"Arfa Daily" wrote in news:CO%qj.6412$ snipped-for-privacy@newsfe5-win.ntli.net:

it would help if he said WHAT MODEL Tek scope,and maybe the part numbers of both CRTs.

part numbers of

Hi Jim,

apologies , i thought i had already mentioned model and P/N. I know you are just trying to help and i am making it difficult.

The scope is a Tek 2232. The bad CRT with P/N: 154-0861-10. The replacement CRT has P/N 154-0861-00 .

I still in process of completing the suggestions/advice you made earlier with astig/geom/gain etc. i planned to revise the operation ststus when completed. thanks for your help Jim, robb

"robb" wrote in news: snipped-for-privacy@corp.supernews.com:

IMO,the 861-00 should work in place of the -10.

Of course,you may have a problem with the new -10 tube.

Don't overlook the CRT socket itself;a bad connection on one pin could cause what you are seeing.Even a pin-corrosion problem on the CRT pins could be the problem;TEK used to make an abrasive-rubber CRT pin cleaner,it's material similar to a Kratex polishing burr. The pin cleaner had a hole in the end and you slid it over the CRT pin and rotated it to clean the CRT pin. (no,I don't have a p/n for it)

I've also seen loose CRT socket connectors,and replaced CRT sockets for similar problems.