Philips DPTV305F

[DavGoodlin]

I know this may be curb material, but I'll ask if its possible to rejuvenate the CRTs in this rear projection set. If I have a correct CRT socket and someone gives the pin-out, I can do the rest. The set functions well otherwise but the green CRT is mush and blue not much better.

[DavGoodlin]

Friend of mine got this a few years back, got some convergence IC kit online and I soldered it in for him. It fixed THAT probem, but the color has been looking worse. I told him I never worked on these but would try so he could go flattie shopping with no regrets.

. Got the pins figured and hooked each color tube up to the CRT tester.
One funny thing is the heater draws so little current that it runs at 8V when the rheo is at minimum.

These CRTs don't quite cut off and all colors show strong emissions despite the green picture looking like a total fuzzy gas-bag CRT.

Tried the clean (AC between cathode and G1) and then said F*** it and hit the REJ, noting a bit of current. No visible changes when we fired it up.

My prognosis, don't bother with these. This set is over 10 years old and was used at a gym, so hours killed it. I always see these at the curb for a few days then the urban urchins destroy them. No loss, just had to find out for m-self.

[ctc17]

Pull the mirror, magnifying glasses off the crts and speakers before you curb it. Maybe its not the crt, maybe I has mold or whatever in the cooling fluid

[ChrisW6ATV]

Projection CRT sets were always run at or near their limits, so I doubt rejuvenating would ever help one for long if at all.

[daro]

Originally Posted by DavGoodlin

Friend of mine got this a few years back, got some convergence IC kit online and I soldered it in for him. It fixed THAT probem, but the color has been looking worse. I told him I never worked on these but would try so he could go flattie shopping with no regrets.

. Got the pins figured and hooked each color tube up to the CRT tester.
One funny thing is the heater draws so little current that it runs at 8V when the rheo is at minimum.

These CRTs don't quite cut off and all colors show strong emissions despite the green picture looking like a total fuzzy gas-bag CRT.

Tried the clean (AC between cathode and G1) and then said F*** it and hit the REJ, noting a bit of current. No visible changes when we fired it up.

My prognosis, don't bother with these. This set is over 10 years old and was used at a gym, so hours killed it. I always see these at the curb for a few days then the urban urchins destroy them. No loss, just had to find out for m-self.

Sounds like the coolant has gone off & require replacement to fix the problem, This was a quite common problem with the CRT's on those units.

[Geoff Bourquin]

I agree that it's likely to be cloudy coolant. I hate that job. It can get very messy.
Seems like the blue is worst, then green. I think whatever that crud is, red light kills it, or at least doesn't encourage its growth, so the red is usually clear. These days I turn down all repairs on these sets; nobody is happy with the results.

[DavGoodlin]

Thanks, I think the set was curbed with a notice posted on CL.
They just disappear then.

[Jeffhs]

Originally Posted by DavGoodlin

My prognosis, don't bother with these. This set is over 10 years old and was used at a gym, so hours killed it. I always see these at the curb for a few days then the urban urchins destroy them. No loss, just had to find out for m-self.

I agree 100 percent. Projection TVs are out of date these days anyway. I would never have one in my apartment. Flat screens -- LCD, plasma, OLED, etc. -- are the sets to have nowadays. If you want to try to get an old projection set working "just for the heck of it" and don't mind spending a lot of time and money doing it, or if you have one that still works (like miniman82's), OK, but always remember that these sets are and have been out of date for some time. When a projection set goes bad and develops a serious problem, best just to put it out for the trash and get a modern LCD or plasma flat screen.

[jr_tech]

I agree that CRT based projection is history, but a DLP front or rear projector is still about the only economical method of producing a really large picture, like 6 feet diagonal or larger. I use a small inexpensive DLP projector that I can just place on top of the printer in my computer room on rare occasions when I want to watch TV there. Not all projection sets are "out of date".



Large, current production DLP rear projection set:
http://www.amazon.com/Mitsubishi-WD-...eywords=dlp+tv

Current model DLP front projector:
http://www.amazon.com/ViewSonic-PRO8.../ref=pd_cp_e_1

Not affiliated,
jr

[Electronic M]

Most schools these days have around 1 of those front projectors per classroom.

[Jeffhs]

I didn't mean to imply that all projection TVs are outdated. The ones using three CRTs, one for each primary color, are well out of date these days (as well as projection sets from the late '90s, such as Zeniths of that era -- I have a full-page ad for one of these sets somewhere around here), but not sets that project images onto an external screen, such as a movie screen.

I can imagine these sets being around for some time to come; in fact, I think they will be. The first DLP sets, with their cooling fans, liquid coolant for the CRTs, and spinning color wheels were just that -- the first generation of a technology still in its infancy at the time. Then the front projectors came out; I'm sure they were much better than those first DLPs, since the front projectors did away with the three items I mentioned (coolant, color wheel and its motor, and the cooling fan[s]), as well as a fixed screen in the cabinet. I can envision these front-projection sets still in use five or more years from now; they just might outlast some current off-brand LCD or plasma sets.

BTW, one other advantage front-projection sets have over rear-projection ones is the former may not use liquid coolant for the image tubes, thereby eliminating the mess inside the cabinet when the bladders containing the liquid eventually start to leak. I was reading on another site recently of just such an incident, where one of the bladders leaked and made a grand mess inside the cabinet. I do not think such a problem can occur with front-projection TVs, since the image tubes are not enclosed in the cabinet and therefore do not require coolant. I could be wrong, but after seeing pictures of some front projectors, I think a small fan would do just as good a job of keeping the tubes cool, with no fluid leakage to worry about.

[jr_tech]

Jeffhs...

Here is an article describing DLP projectors. Both front and rear DLP units use essentially the same types of imaging components. The light path in a rear projector is "folded" by the use of mirrors, so that it "fits" into a small box behind the screen, rather than projecting across the viewing room. They do not use CRTs or "tubes".
http://en.wikipedia.org/wiki/DLP_projector
jr

[Einar72]

Nothing says look at spreadsheet in meeting where personal production numbers are discussed like a video projector. Ugh.

[DavGoodlin]

That was a great wiki page on DLP. I just became interestd as I need to repair one

I just got this one (DOA) from a friend who upgraded to a new Samsung Attachment 176219

The power-on circuit is reputed to have a few bad electrolytic caps I need to find.

[Jeffhs]

Originally Posted by jr_tech

Jeffhs...

Here is an article describing DLP projectors. Both front and rear DLP units use essentially the same types of imaging components. The light path in a rear projector is "folded" by the use of mirrors, so that it "fits" into a small box behind the screen, rather than projecting across the viewing room. They do not use CRTs or "tubes".
http://en.wikipedia.org/wiki/DLP_projector
jr

"Tubes" is a term I used so that I would not repeat "CRTs" twice or more.