CRT Monitor anode cap hissing? (FIXED)

Heinz

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My Mitsubishi XC-3715C 37" monitor was fine when I bought it, I could feel the static on the front of the tube everytime I turned it on. But just recently the static has stopped and a hissing noise was coming from the back of the monitor.

I finally took off the rear metal housing and inspected the monitor and boards for any damage. All boards are clean, little dust but no burning or leaking of caps.

I turned the monitor on with its housing off and got a real good listen to the parts. The hissing is coming straight from the anode cap. Theres no blue ring or anything abnormal looking around the cap but it kind of looks like its stuck down. I'm not sure as it's far too dangerous to poke my fingers into this thing on or off.

Anyone experience this? a solution perhaps?

The hissing is much louder when on a white screen as aposed to a dark one. Picture is fairly perfect for 20 years old, so no distortion.
 
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channelmaniac

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Discharge it then clean the dust off the top of the cap and around the side of the tube.

Don't clean off any sticky liquid looking stuff. That's supposed to be there to prevent the corona discharge you see.
 
Heinz

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channelmaniac said:
Discharge it then clean the dust off the top of the cap and around the side of the tube.

Don't clean off any sticky liquid looking stuff. That's supposed to be there to prevent the corona discharge you see.
Click to expand...

I knew it!

Okay, I know how to discharge tubes but I've never actually done it.

Can I pull ground from the ground socket in my house? or is it better to ground to where the silver braided wire is connected to?

I've got a screw driver with a plastic/rubber handle and sufficient wiring. What precautions should I take? any thing I should look out for in particular?
 
channelmaniac

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Just clip the wire to the monitor frame and to the screwdriver then slip the screwdriver tip under the cap until it touches the metal in the middle.

You may hear a slight sizzle and a crackle when it discharges. It's not a big thing at all. You'll be surprise at how simple it is.

Wait 5 minutes then repeat with the screwdriver to make sure it's fully discharged.

RJ
 
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Alright.

Just as a precaution here is a picture of the inside of the monitor.
2wgaxsn.jpg


I'm thinking the outisde most frame or the one covering the tube. It's a little scary, I really dont want to blow something.

I have found that on the bottom of the monitor, the very bottom which looks like it touches nothing else, has a cable going to it with a ground logo sticker next to it.
 
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channelmaniac

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All of those metal pieces should be connected together for ground so it shouldn't matter.
 
Heinz

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Okay well I went to discharge the monitor but there seems to be some kind of rubber ring ontop of the anode cap with a pretty strong glue in between making it exceedingly hard to get off.

So no shocking myself yet, that's still to come. HOWEVER... the hissing was reasonably quiet after my attempt.

Here is the anode cap with the rubber ring and glue. This shit is the only thing stopping me arrrgg!!

It almost looks as if it has been serviced or something, when I had my Nanao 29" the anode cap had no such thing.

amryjd.jpg
 
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Gunbu

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Yeah that sucks, never seen the rubber cap glued on either. My suggestion would be to try a thin bladed putty knife (with a rubber or plastic handle) and slowly work your way around the cap to release the glue.
Here's a video a KLOV member uploaded a little while back that you may find useful:
http://www.youtube.com/watch?v=WX43sT0hMJk

A couple other things that may be common sense but I'll say them anyway:
- Make sure the machine is unplugged.
- Wear rubber gloves, dishwashing gloves work well.
- When discharging, only use one hand. Put your other hand in your pocket. This is a safety precaution so if you do get shocked by the anode, the charge won't pass through the middle of your body and find ground through your other arm.
- Try not to scratch the glass tube too much when you are removing the cap.

Here's an example of a discharger:
http://www.therealbobroberts.net/sb.html

Good luck!
-Eric
 
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Gunbu said:
Yeah that sucks, never seen the rubber cap glued on either. My suggestion would be to try a thin bladed putty knife (with a rubber or plastic handle) and slowly work your way around the cap to release the glue.
Here's a video a KLOV member uploaded a little while back that you may find useful:
http://www.youtube.com/watch?v=WX43sT0hMJk

A couple other things that may be common sense but I'll say them anyway:
- Make sure the machine is unplugged.
- Wear rubber gloves, dishwashing gloves work well.
- When discharging, only use one hand. Put your other hand in your pocket. This is a safety precaution so if you do get shocked by the anode, the charge won't pass through the middle of your body and find ground through your other arm.
- Try not to scratch the glass tube too much when you are removing the cap.

Here's an example of a discharger:
http://www.therealbobroberts.net/sb.html



Good luck!
-Eric
Click to expand...


Yeah I will be thinking about getting a knife or even a sharper flathead screwdriver to pry it off. The thing I want to know is, was it stuck down for a reason? perhaps a repair? or just that's how it came from the factory.

That youtube video was great, thanks. That discharge tool that bob roberts made, a good way to complicate a simple tool. I've just connected a 3 wire cable to my screwdriver and then taped down with electic tape.

It looks like scratching but most of it is bits of glue.


http://www.youtube.com/watch?v=c4GB1ui8WR4&NR=1 This idiot is a good example of what not to do, I think!
 
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Heinz

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I just got under the glued down part, pushed the screwdriver right up until I felt something metal. Not sure, no sound at all.

I just turned it back on... and now theres a lot more hissing and visible electricity coming from under the anode caps cover/glue that was pryed open by me.

I don't really understand why, I will try and discharge it again and see.

I would really like to get the anode cap off and just clean around the whole thing. But I'm not sure if its fully discharged or not. No sound, pop, crackle. Nothing.

Due to it being 37" will 5mins between discharges be sufficient?



EDIT:

Finally got the cap off, theres no sticky liquid either. It definitely looks like part of the anode cap was torn off and someone has glued it down with a cover.
 
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Heinz

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Alrighty, discharged it. Anode cap off. I then cleaned the cap and the hole with alcohol.

When I put it back together and turned the TV on again. The hissing is very loud and the anode cap is leaking visible electricity, alot of it.

I'm not sure but I think the anode cap had the cover glued over it for a reason. Some sort of leaking problem?
 
channelmaniac

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You'll need to find a new rubber cap if the one you have is torn ANY little bit.

Also, when soldering the cap onto the wire you have to beware that ANY pointed bit of the solder joint will be a source for corona radation, sparks, and noise. The solder joints should be slabbed on and everything rounded.

RJ
 
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channelmaniac said:
You'll need to find a new rubber cap if the one you have is torn ANY little bit.

Also, when soldering the cap onto the wire you have to beware that ANY pointed bit of the solder joint will be a source for corona radation, sparks, and noise. The solder joints should be slabbed on and everything rounded.

RJ
Click to expand...

Ahh I see. So instead of replacing that cap like they should have, someone has glued it down with a cover. It's only torn on the very edge, goes to show what can happen even when the damage is that small.

I'm wondering if just doing the same, gluing it down again, will be alright. I have no idea where to get the same special glue though. It has a rubber/foam squishy texture. But I think repalcing the cap as you've mentioned would be a much better way to fix it for good.

I can use any anode cap right? If I take it from an old monitor or something, it should suffice yes? It's going to be a little tricky soldering a new cap on without taking the anode cable out of the flyback. Can you do that?

Is there any online shop or something that would supply parts like this? or will I be hunting down junk monitors?

At the end of the day, the monitor still works and has a beautiful picture. Hissing or no hissing.
 
channelmaniac

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At the end of the red cable, under the rubber cup, is a set of clips that fit down into the hole on the side of the tube.

When you get it discharged you can pop those right out.

RJ
 
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channelmaniac said:
At the end of the red cable, under the rubber cup, is a set of clips that fit down into the hole on the side of the tube.

When you get it discharged you can pop those right out.

RJ
Click to expand...

Yeah, I've done that a few times testing it. The anode cap is off at the moment.

Just replacing or fixing it is the problem now. I need to know if I can just use any cap from a random monitor. That way I can just pick up a dead pc monitor and steal its cap.
 
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I've gotten a quote from a TV repair shop. Will run me about $150 aud to get it repaired by a tech. Damn thing is so heavy I can't get it to the shop which is bumping up the cost because the tech would have to come to my house.

Is it really worth it getting a tech to do it?

Can you get the anode cap off the red cable without damaging the cable?
 
channelmaniac

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Look and see how the metal clip connects to it... is it crimped or is it soldered?

Can you get the wire to separate from the cup?

Depending on the answer to this... you could find it easy or a PITA. ;)

Hell, you can always try to find a new flyback.
 
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Okay! I found that the red wire has a crimp onit with two prongs. So no solder!

I think getting the wire and crimp out of the cap without cutting the cap off is going to be a little bit hard but I think it's doable with a bit of TLC and patience.

When I replace the cap, can I just clean the cap and anode hole surface area with alcohol and then apply the cap? or will I need some sort of protective liquid?
 
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channelmaniac

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Give it a try and see... sometimes you do, sometimes you don't. The hard part is, I don't know what that gunk is they put on the monitor.
 
Gunbu

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Channelmaniac knows way more than I do, but maybe I can add some support.
To get the glue off the tube, I recommend Goof Off, Bestine, or Zippo lighter fluid. Not sure if you can get the first two where you are, but Zippo (or Ronsonol) fluid works awesome for getting off adhesive. Afterwords you can use some alcohol to get off the remaining residue, just be sure to keep it only on the glue that was on the cap.
Also, could it be the two prongs on the end of the cord weren't fitting into the hole properly? If one wasn't properly inserted maybe it was causing it to act funny?
 
Heinz

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Getting the glue off will be a bit frustrating but won't be too hard. It feels like rubber but softer.

I don't think it was the prongs, those things were well and truly inside the anode hole. Trust me, wasn't easy getting it out.

The side of the anode cup had been torn off so its creating a very easy path for the electricity to escape. and I think over time a hole was created in the glue and that's why it started hissing. Overall the cup was damaged and wasn't replaced when it should have been.

Can I use any anode cup from any monitor? keeping in mind solder/crimp cups.
 
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channelmaniac said:
If it's the same size or a little larger, yes.
Click to expand...

Fantastic, now I just need to find a replacement.

I will try and pick up some dead monitors/tv's and see what I can do. Unless someone here can sell me one.

Tricky part now is finding a way to get the cup off the wire. The crimps are making this hard to do. I need to see if the red cable can be taken off of the flyback.
 
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