Monitor II on the fritz

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CWJ_Wilko's picture
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Monitor II on the fritz

Hi there,

Hoping someone can help me out. My Monitor II has been working almost flawlessly ever since I replaced the line capacitors, but lately it's making a noisy hissing noise for the first 15 minutes of operation. This noise descreases in volume before disappearing almost completely, however I can still hear very faint pops and crackles coming from inside the case.

I'm familiar with electronics but haven't been brave enough to discharge the monitor and clean around the anode cap, most posts online about this issue with other CRT monitors point towards a buildup of grime and dust being the main cause. It's not really that dirty inside, however I'm sure after 30 years of use, every part of it probably needs a clean.

Can anyone think of anything else I can try before I attempt to discharge and clean?

And additionally, is there anyone in Sydney Australia that can recommend a professional to do this for me? Perhaps a hobbyist that wouldn't mind helping me out?

Cheers
Chris

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Re: Monitor II on the fritz

Hard to say, but you might try cleaning all the connectors. Mine recently blew it's fuse and I never found any issue, but reseating the connectors reduced current draw by half. There is a SAMS service manual posted online, which will give you nominal voltages at many locations.

regards,
Mike Willegal

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Re: Monitor II on the fritz

So I've pulled the Monitor II apart again today, all connectors look clean and the mainboard looks pristine. My previous work on the line capacitors looks fine as well.

I did manage to discharge the flyback using a screwdriver, but I was concerned since there was no sparking, even though I definitely hit the metal anode prongs. I still couldn't get the cap off even after I was brave enough to get at it with my fingertips.

I covered a tiny tear in the anode cap with some tape which is by no means permanent. I just want to see if it makes a difference over the course of 24 hours as to whether the hissing becomes louder again. I also adjusted the position of the anode cap as much as I could so that it's seated better but not much I can do.

Monitor II is back together and working. There is a small hissing noise currently but nothing too loud. It's bearable but not ideal. Will have to wait 12 to 24 hours to see if it becomes loud again after being turned off.

A few high resolution pics are included below for inspection. I think the Monitor II could still use a proper service so again, if anyone is in the Sydney area and wants to help a guy out, there's a case of beer in it for you.

http://i59.tinypic.com/8x0d2v.jpg

http://i58.tinypic.com/xktxqa.jpg

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Re: Monitor II on the fritz

CWJ_Wilko,

I'm sorry that I cannot help you with the monitor problem
as I have never had to work on one.

The closest I made it to Sydney was Adelaide in 1982.
My ship spent a week in Adelaide, one in Hobart, and one in Newcastle.

And as for beer...
It's a Fosters for me, mate. lol

Steven Smile

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Re: Monitor II on the fritz

No problems Steven. Still hoping that someone may have an idea or two left. At least it hasn't died completely (for now).

And just to dispel any misconceptions straight away, we rarely drink Fosters here (but I think it was prolific in the 80s). I would possibly drink more of it if it wasn't so hard to find locally! It's not a bad drop, but I think I'm in the minority on that one.

Still thinking that putting some money away for a professional to look at the Monitor II, but even they are hard to find these days.

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Re: Monitor II on the fritz

Is the noise changing if you connect/disconnect the video signal to the monitor? Most likely yes and most likely the noise is produced by the flyback transformer. Nothing critical by itself, the monitor will work for many more years, the sound could be annoying to you and people that still hear noises around 16kHz and above...

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Re: Monitor II on the fritz

I know the noise you mean, I've heard it on a lot of CRTs before. More of a high pitch electrical whine. While that's present on my monitor, the current noise is more of an electrical hiss that is only recent.

It sounds like (and probably is) thousands or millions of tiny electrical sparks happening every second.

From what I've read online it's electricity escaping from underneath the anode cap and into the open air where they fizzle and spark. On some old CRTs you can actually see this happening, the back of the TV can glow in the dark! But mine isn't that bad.

I'll be heading home from work momentarily to see if the hiss is back after a day, not holding out for a result after my fiddling from earlier.

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Re: Monitor II on the fritz

No dice. Still quite a loud hiss.

Although I did run an unintended burn in test after I forgot to turn off the Apple //e for over 12 hours. Still works! Didn't burn the place down.

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Re: Monitor II on the fritz

... but I was concerned since there was no sparking, even though I definitely hit the metal anode prongs. I still couldn't get the cap off even after I was brave enough to get at it with my fingertips.

Although we all hear the warnings about CRT's holding a lethal charge, the fact is that most will discharge safely soon after being shut off. So it is certainly not unusual that you did not see/hear any spark when grounding the anode clip. But of course that is what you should do if you are going to work around the HV. By the way, the clip prongs need to be squeezed together from the top to remove from the tube.

As for the hiss, it definitely could be a breakdown of the insulation around the cap or in the anode lead. You are correct that sometimes you can even see the arcing by turning down the lights. You might even get the telltale smell of ozone as well. Electrical tape probably would not fix. Best solution would be to get some glyp insulating varnish ( 4228 Red GLPT ) and coat the area where you suspect the problem.

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Re: Monitor II on the fritz

Jeff that sounds like just what I need, thanks. Last night with all the lights off I did indeed see some brief flashes of purple sparks coming from around the anode cap, so think that's where the problem lies. The back of the Monitor II stinks of ozone as well (or at least what I assume is ozone). The lead between the flyback and the anode cap looks intact so don't think that's the issue.

Looks like time itself has degraded the grip that the anode cap had against the monitor itself. I was thinking about using some kind of high voltage high temperature glue as suggested elsewhere, and as Jeff suggested. I'll go from there and report back next week.

Should the anode cap be sealed to the monitor? Should there be any gap between the monitor and the rim of the anode cap?

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Re: Monitor II on the fritz

I was thinking about using some kind of high voltage high temperature glue as suggested elsewhere, and as Jeff suggested. I'll go from there and report back next week.

Should the anode cap be sealed to the monitor? Should there be any gap between the monitor and the rim of the anode cap?

I don't think I'd be using any glue here. Just remove the cap and inspect around the hole where it enters the CRT. Clean both the cap and the CRT and see if there is possibly a small chip or crack in the glass around the hole. This can be fixed with the glypt varnish. If the metal prongs keep the cap from coming off without squeezing then there is probably nothing wrong with the connection. It will have a little play but the rubber "suction cup" around it should keep it tight against the tube.

If you fix the problem, you should also be able to test the connection with the power on. Just take a wooden ruler (make sure it's not one of those with a small metal edge!) and gently move the HV wire around. If you don't hear any arcing you're good to go.

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Re: Monitor II on the fritz

Thanks Jeff, made some progress this morning.

It took a lot of poking and prodding but finally managed to get the anode cap off. Those prongs were in there tight, so don't think there's anything wrong with the connection there, as you said.

Haven't made it to the store yet so couldn't get that varnish, but couldn't see any chips or cracks in the hole anyway, everything looked really good. I cleaned up the entire area with isopropyl and wiped it dry.

Wiped off a lot of the blue stain around the anode - I heard from another source that this may be insulation, so didn't want to get rid of too much, is this true?

I also patched a small tear in the cap with some electrical tape until I can find something better. I've heard that Araldite can be good for sealing a tear like that, however I may still go get the whole cap replaced by a professional who knows what they're doing.

It was just about impossible to get the clips back in the hole but got there. So far the hissing definitely is quieter, but not gone completely. If it stays like this I can probably live with it!

Thanks very much for your help, I'll let you know if I have any further progress.

Chris

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Re: Monitor II on the fritz

Hissing has come back again. I'm really starting to think about sealing that anode cap to the tube with some epoxy or some kind of high temperature glue. I've seen Araldite thrown around as a possible glue to use, or some kind of silicon sealant.

Does anyone have a good reason not to try this? It's definitely a problem with the anode cap. I could use the glue to seal up the small tear in the rubber and then to make a seal against the glass.

I've gone off the idea of getting a professional to look at it, as I could spend that money on something else, like more peripherals or even just a new-old Monitor II or Color Monitor.

I will never have the opportunity to replace either the flyback and anode cap, or the actual tube itself, so I feel like permanently sealing the anode cap to the glass is the way to go.

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Re: Monitor II on the fritz

Don't think it's an issue with sealing cap to glass. Must be some discharge path near the anode connection. I still think it might be somewhere on the glass itself. You mentioned some blue residue there; could possibly be due to the arcing.

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Re: Monitor II on the fritz

The blue material came off easily with some isopropyl, still not sure what it was.

But it has been almost perfectly applied to the monitor in a circular pattern, perhaps some kind of insulation that was sprayed on. Wiping some off may not have been the best idea.

But at least sealing the cap down would rule out arcing from underneath the cap itself, right? As long as I can still get underneath if I really need to for discharge.

BUT... First, I could try wrapping the HV lead with a few extra layers of electrical tape to see if there is any difference.

I'm pretty sure I've seen purple static discharge from underneath the anode cap itself, which is why I'm so convinced that it's trouble.

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Re: Monitor II on the fritz

If you've seen the discharge from under the cap, then I see three possibilities.

1. The connection between the HV lead and the anode prongs is bad.

2. The connection between the prongs and the CRT is bad.

3. There is some discharge path from the anode connection to some other part of the CRT.

You can easily check for the first two conditions by gently moving the HV lead while the monitor is on. If there is no change in the hissing sound when you do this then I would rule them out. That would leave the third possibility which is actually an arc on the tube itself. So sealing the cap down will not actually have any effect. You need to insulate the glass itself around the anode connection. Maybe the blue material was doing that and developed a small hole. In any case the glypt should be able to fix this quite nicely. I don't think electrical tape would work either.

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Re: Monitor II on the fritz

Thanks as always Jeff. Thinking the varnish is something I'll try soon. Having a hard time sourcing it locally in Australia though, would prefer not to have it shipped in.

I see your point about sealing the cap down: if there's a path for electricity to arc along the glass, it doesn't really matter how well sealed the cap is. Which is why insulation would seem to be what I need.

Or maybe I'll just have to live with the smell of ozone...

EDIT: This is pretty much the same stuff, right? Still more than I would want to pay but might have to do: http://www.ebay.com.au/itm/RED-AIR-DRYING-VARNISH-ELECTRIC-MOTOR-COIL-INSULATING-VARNISH-100ml-/141191484871?pt=LH_DefaultDomain_3&hash=item20dfab15c7

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Re: Monitor II on the fritz

The product you linked looks like it would work too. Of course, you COULD try a few coats of nail polish (non-glitter!) or something similar. Nothing really to lose.

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Re: Monitor II on the fritz

Isn't nail polish flammable? Definitely would be a good insulator but with the arcing already present it might be a bit risky, I would have thought.

I might head down to my local electronics store and get some of this, might be an option too? http://www.jaycar.com.au/Service-Aids/Tapes/Electrical/Liquid-Electrical-Tape---Tube---Red/p/NM2838

EDIT: Wow!!!! I will have to take a photo of the electric discharge surrounding the anode cap in the dark. Looks extremely deadly. It escapes about 5mm out underneath in every direction. Looks sci fi.

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Re: Monitor II on the fritz

Kinda like a Tesla Coil?

Steven Smile

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Re: Monitor II on the fritz

Kinda like a Tesla Coil?

Steven :)

Or a Borg alcove...

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Re: Monitor II on the fritz

I've coated the area around the anode hole in liquid electrical tape and have had minor success, the hissing noise is softer but still not gone. It takes a shorter amount of time to 'settle' as well, where the hissing noise eventually goes away nearly completely. But otherwise, still the same problems.

Not really sure where to go from here, the glypt recommended seems to be similar to the liquid electrical tape as far as insulation and consistency go, so thought I would at least change something - even for the worse or the better! I might try another coat of the liquid tape and may even try and seal the cap on using the same goop. Nothing to lose at this point. Quite frustrating.

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Re: Monitor II on the fritz

You might also try pushing the HV lead into the cap. This should push the prongs out so you can inspect the connection between the two. You could even attach the prongs to the CRT (now that you are probably quite comfortable working with the anode connection) and turn it on. This might help you figure out where the arcing is coming from. Be just a little more cautious!

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Re: Monitor II on the fritz

After leaving it for 24 hours I've tried it again this morning and found that the hissing has almost disappeared completely, probably about 97% gone. Good enough for me! I'll keep an eye on it over the next few days to see if it plays up at all.

Thanks everyone for your patience and tips, I've learnt a lot about these old CRTs which I'm sure will come in handy again some day. As these monitors get older and TV repair becomes less common, I'm sure I'll be needed again!

For the record: In my case, the HV lead seemed to be fine, and visual inspection at nighttime showed the electricity escaping from underneath the anode cap.

First you would try to simply reseat the anode cap to make sure it's a firm fit, but failing that, my recommendation would be to use liquid electrical tape to insulate the area surrounding the anode hole, from the lip of the hole and at least two inches beyond the lip of the anode cap. A decent clean of all internal surfaces isn't a bad idea either. Glpyt varnish or other similar products are probably a better choice but the liquid tape worked for me this time. Do not use regular electrical tape, must be applied in liquid form.

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