Procedure for changing CRT Coolant - Page 2

Johnny G,
I need a little info if you can help. I am trying to clean the inside of the crt's in my magnavox which is 10 yrs old. I have checked my web locations for info. I can find nowhere where it tells exactly how to drain and refill the coolant. I mean exactly. I read many places where it is discussed whether to drain in the tv or pull the crt. It seems a toss up. However, I am here to tell everyone....please take the advice of people in this forum..pull the crt! When you pop open the top lense (break the seal) the coolant does in fact basically blow out. I was heading for sudden death any way you look at it but I was to the point of no return. I took off the top lense not knowing all I then had to do was break the seal on the lense and it would expose the fluid. So, I took off the lense first, then started to remove the 4 long bolts that hold the entire fluid chamber to the crt tube. Got them basically loose and nothing was coming loose. So, I proceeded to break the seal on the lense cap and the fluid gushed out. One way or another I was going to get fluid on something.
My question...Some of the fluid leaked down into the wiring that connects to the ring right below the tube itself and right above the adjustment tabs. Can I buy something to spray all the connections to make sure it is very dry before I reinstall in tv? I read this fluid is highly electrically conductive. So you know where I am headed. Please don't tell me I am basically screwed. Any help appreciated on this.
Thanks
Pelogius

Nick,
Hey, Guy...How did you ever make out on this whole project of changing the coolant..

pelogius..

Just FYI, there are a number of very helpful guides for CRT change, coolant change, defungusing that can be found here:

http://www.curtpalme.com/Advanced_Procedures.shtm

Hi,

I'm a newbie to this forum. I'm a retired TV tech. that worked for Sears for many years.

My buddies Mag projo needs the fluid for the 3rd time. I did the 1st 2. Seeing as how the fluid is cost prohibitive, I did a little research on eBay and found a 16 oz. bottle of 100% Pure USP Grade Propylene Glycol that's supposed to used in cigar humidors of all things. Price $6.00. Maybe it's time for experimenting. I asked the seller if it was perfectly clear but haven't heard back yet.

I should have also mentioned that I have changed CRT fluid in these sets dozens of times. The later models with digital convergence were much easier and accurate than the potentiometer method. I almost found it enjoyable!


Jim

It's best advised to change the fluid with the tube out of the set. Some guys in the shop like to do it on-board but personally I can do it just as fast by pulling the tube. Removing the tube is no big deal, after removing the front screens and back cover you'll have to pull the crt socket board off. This is probably the hardest part since Philips puts a glob of RTV between the socket and the tube, as you're pulling down, gently wiggle the board, it will pop off. You'll have to pull the HV anode lead out of the HV block on the LSB board in the back. Unplug the convergence plug for the particular tube you're changing as well as the Yoke plug. There are normally 2 ground wires connected to the backside of the CRT metal shielding. Those have to come out. After removing the 4 1/4" screws holding the crt down, slowly remove the CRT. BE very careful that you don't bang or bump the certering rings when you remove the tube. Those are a pair of rings around the neck of the crt with tabs on them. They're usually RTV'd down but they can be moved. If you move them you'll have to recenter the tube.

You'll find the plug on the top of the coolant chamber, twisting 180 degrees loosens it so you can remove it. Careful, there's a small white washer you must keep and it tends to fall and can get lost. Drain your coolant into a container like a kitty litter container. After the fluid is drained, removed the 4 screws holding the lens on and clean the inside of both the lens and CRT coolant chamber with a rag. Reinstall the lens. Sit the tube upright, begin slowly filling the chamber back up with the replacement fluid until it reaches the very top. Reinstall the cap with rubber gasket washer and tighten 180 degrees. Clean any coolant on the outside of the tube off, you don't want any of this stuff dripping down into the set.

Reinstall tube the same way you removed it. As long as you didn't move those centering rings, any convergence adj. should be very minor. Proceed to do the same to the rest of the tubes.

Normally the blue tube dirties the worst and fastest. The glycol based coolant is extremely sticky and corrosive as well as conductive. If you do the coolant change in the set and you spill any coolant on the PC boards, STOP WHAT YOU'RE DOING AND CLEAN UP THE SPILL IMMEDIATELY! AS I said, this stuff is conductive and will short circuit the boards it's spilled on quickly.

If you're not comfortable doing this call a pro.

MOtvGUY's way is the way I did it for years! I wouldn't even consider changing the fluid while the CRT's are still mounted. If you're doing it that way your going to spill stuff everywhere, and your going to do a crummy job too! I like to take the lens and the CRT and wash all surfaces that come in contact with the fluid under the tap. You want to get as much of that Primordial Soup off as much as possible.

I was told in a Seminar that the red CRT almost never has a problem due to the red spectrum which the little bugs or plants or whatever find lethal. The green gun is worse but not as bad as the blue because green has red in it also. The blue gun has no red and therefore no defense, so the fluid goes noticeably bad after 3-4 years. They also told us that this was happening because some drums of the stuff didn't get Pasteurized, "but the problem has been corrected". Yeah right! Well it was very good job security.

Jim

I have a Hd65w20 RCA Scenium HDTV rear projection. I only have the blue color working on my TV. The red and green does not work. Everything else is working fine. How can I tell If I need to refill my coolant liquid or if it is something wrong with my board that has shorted out? If I do need to replace coolant, what kind of coolant should I get and were could I get it from? thanks in advance for any help you guys could offer.

Perhaps a circuit failure, such as drive transistors, but coolants don't become opaque enough to block light completely, and not all CRT-based RPTV displays use liquid cooling. Needs a repair tech to troubleshoot IMO. -- John

how did you do it? any more pics?

My grandma's TV has the exact same chassis and the horrid coolant problem... but I don't want to work on it and then not be able to put it back the way it was.

hey guys srry to bring up an old thread here but um, i have a philips/magnavox 9P6034C1 crt rptv and the color it shows is more of a red i have adjusted the tint, color and everything i can think of but the main and really only color you c is red when watching tv, theres no green from what i can see and the blue you can some what see, just in darker areas, you dont actually see a picture just random lines, ive taken th screen out and looked at the crts and the red looks perfect you can actually watch tv throught the red crt projector but the blue it looks like has algie all in it looks like the pic posted by nick and the green crt isnt lit, it will come on every now and then but wen looking down in it all you c is a couple of green lines, no actuall picture, like when watching star wars the only time you see a picture on the green is when a lightsaber is swung or something like that.
does the coolant need changed a new bulb or something plz help asap,
i brought this up because the blue tube looked the same as nicks and i was thinking maybe im having the same problem as him just worse. so plz help any would be appreciated.
thnx,
deadlydayne

^^^Reads like you'll need both blue and green fluid replacements. Hard to imagine that much algae buildup in the green. After completing blue/green coolant change in my year-2000 Philips 64PH9905, found all images were too red. Marked the positions of red, green, blue screen-bias potentiometers (see earlier posts here), then adjusted the red bias pot down, which cured the problem. Gray scale tweaking (outlined in general here ) may be necessary after adjusting screen bias pots, and the Philips coolant change instructions I used (under CRT replacement) said gray scale recalibration is recommended after coolant change. Knowing I'd have to adjust gray scale anyway, with your symptoms, here I'd probably adjust the green bias pot somewhat higher (not full) while peering into the lens, but quickly return it to its preset position. A brighter green image during the brief bias adjustment would suggest it's a severe fluid contamination problem. (A search for Philips threads in this forum for ~6 months back points to several fluid-change threads.) Changing a bad green CRT tube is possible, but if fluid contamination isn't the problem, all the CRT-drive and signal circuits, or perhaps even a green signal input cable (the Y in YPbPr), have to be eliminated as culprits first.-- John

so wat ur saying is that i should just have to change coolant in the blue and green and that should be it? if u could plz send some links on a site or sites on where to order this coolant and maybe a bulb for the green thnx ur help is much appreciated

^^^I'd want to pin down whether the green CRT fluid was actually that contaminated. The procedure I outlined might help with that. If you track the Philips/Magnavox fluid-change threads, most have replaced the green/blue fluids but not the red. I and and few others have used this source for coolant, not the factory stuff originally causing the problem (years back at least). Suggest using the forum search feature and study threads on Philips coolant change going back about one year. Good idea to access a service manual, too, that spells out procedures for your model. Philips has transferred parts resupply to andrewselectronics.com (replacement CRT), and Mr. Bob often mentions CRT sources in his don't-dump-CRT-RPTVs thread. Again, it's unlikely the green CRT itself is bad. -- John

just wanted to throw in a comment on changing fluids with the crt's still mounted. I did this on my magnavox a couple of years ago. The procedure is pretty simple. Basically, you syring out the old fluid thru the drain holes that usually are at the top of the lens stack. Then, decouple the lens stack to clean the awful stuff that has coated the tube and lens area. Replace everything and syringe in new fluid. This method saves you from having to so any realignment and "stuff"... which for most DIY's is probably not going to happen easily. Yes, the method can be dangerous if you release the lense stack before you empty it but on the magnavox at least, you can lift away the top elements once you have drained / sucked most of the fluid out, then you can get directly at the fluid cavity with paper towels to ensure that the rest of the fluid is gone before releasing any seals in the lower portion of the stack.

kk cool thnx budwich do you have and pics or instructions or directions on how to do this, cause i really dont want to remove the guns from the tv, but if its the only way ill do it. but if this is an easier way to do it then plz help with that, now in my picture when the tv is on the blue is completly fuzzy, like when adjusting the convergence the red is crisp and clear the blue is fuzzy and there are letters on the screen telling you how to converge and menu options but i only see some dots and lines no actuall words at all, does that mean the green bulb needs changed completly? and that the blue one just needs changed? and what all do i need to changed the coolant, do i need just the coolant or do i need some sealants and other stuff?
thnx for your help

If you search the RPTV forum for Philips, coolant, fluids, posts by those changing coolants and fixing sets professionally, all urge CRT removal before coolant changes. A detailed outline, apparently by Philips, under picture tube replacement , (covering coolant change, too,) describes how to remove CRTs from sets. -- John

dude john ur a beast sorry for all the questions but i just got this tv and i am new at this stuff so thnx

wat is the plug (K) on the crt tube? in these instructions http://www.keohi.com/keohihdtv/brand...placement.html
is it that big black plug sealed to the side of the crt tube? because i dont have any sealant to reseal that if thats it.

My Tv was about 10 years old at the time and not worth a service call to this done and I wasn't going to chance disassembly of the "whole thing". My understanding (from a few posts here) is that "people" use any form of suction to lower the levels of fluid in the lens chamber.... then remove the top elements without decoupling the lens "stack" to remove the rest of the fluid and totally dry things off. They then can decouple the stack (which I did) and totally clean all surfaces. The remount and refill. You have to watch when you refill cause if the stack seal is not completely good (ie. has deteriorated), then a leak, any leak will be a problem. this is one of the reasons for demount the crt's but if you keep an eye on things, I think you can check for leaks over a long period( a day or two) and only initially partially filling the chamber. I don't really have much more of procedure that that. Each TV is probably different so check your drain holes and expansion tube areas.... I personally think it is readily doable by a DIY but as you have been warned by others, if you are not careful, any leaks or mishaps will be a problem. As for sealant, I did not use any as the seals were good on lens stack.

If a sealant is involved, you may be referring to the anode-lead connection on each CRT. It has a thick high-voltage wire. That should stay in place.

The plug (k) seems to vary with RPTV models. These instructions are referring to a small plug where the coolant can be drained.

My year-2000 64PH9905 Philips has a different setup, with a small chamber offset from the main coolant chamber, for heated expanding fluid, with a small hole in its base for emptying and refilling coolant. -- John

BTW, don't partially refill any coolant chamber!!! The coolant protects phosphors from overheating and 'cooking'--permanent damage. Suggest meassuring how much fluid you drain so you know, along with viewing the level, how much fresh coolant to replace.

ok just to make sure i have things correct the small glass tube connected to the circuit board is the well the crt tube and the big bulb end is the expansion chamber correct or do i have it backwards cause i cant find a drain plug anywhere

^^Suggest studying the photos drmax took of his coolant change--and others. The glass CRT stands out--distinctly--from the metal coolant chamber attached (bolted) to it. Fluid in the coolant chamber absorbs heat from the CRT phosphor face. -- John

IF you have trouble identifying the crt, lens asembly and expansion tube... then my suggestion of a fluid change are probably not good... as I do expect a "little understanding" of crt RPTV operation.

As mentioned, do not restart your TV with partially filled chambers... my suggestion was to fill them a bit and check for leaks over a "period of time" ... no leaks, keep filling til you replace the amount of fluid that you took out... use a measuring cup as a holder to measure fluid.

I don't get a good feeling from your question.

nono, coolant change went fine everything works

glad it worked out ok... I assume you didn't remove your crts... right?

Nope I didn't I did 1 at a time and changed coolant I had some probs wen finished like my green wouldn't work but the longer I messed with it the more I fixed it. The greeen crt works fin but I my current problem is I can't adjust the sharpness of it with the dials inside the tv. And my second problem is when multipoint converging all my outside points are fuzzy and look out of focus any ideas?

hmmm... it sounds like you "turned" your lens element/stack (meaning that you rotated the mounting hole...maybe???). They should have stayed "locked" and if they were put back in the same position, your focus should have been unchanged from before.

Glad to hear that your green crt is running better... bonus.

When I did my change, I couldn't believe the color of the old ... like cooking grease that had been used for months.

Hopefully, someone will pipe in on the focus issue.

My old magnovox didn't have any "soft focus" controls... at least nothing that I could get at from the user menus... old manual adjustments on the lens stack... which I was afraid to touch. I wonder if your set needs some sort of "service menu reset" to bring things back from trying to correct "dirty fluid".

Focus should be mechanical (lens position) and electrical (focus pot), with two CRTs covered at a time and ideally a crosshatch test pattern. Outside multipoints would seem fuzzy until they're converged properly. If user convergence isn't adequate, use the service menu convergence.

If you didn't remove the CRTs how did you clean all the coolant-assembly surfaces and CRT face to eliminate the algae multiplying again in the fresh coolant? -- John

http://www.tv-forums.com/forum/TV_Eq...rgence_P50090/

I documented the procedure I did on the link above. For convergence issues try this link:

http://www.tv-forums.com/forum/TV_Eq...issues_P50073/