Zenith Projector 1985

[radiotvnut]

I have increased the heater voltage to bring back old tubes, especially ones that had not been used in years. The normal filament voltage is 6.3. I usually use around 8 volts. Most TV parts suppliers sell brightners that can be soldered between the filament winding of the flyback and the CRT filament that will boost the filament voltage.

Before you buy a brightner, connect an 8 volt source to the filament and let it cook for a half hour or so. Then, remove the power source and connect the CRT for normal operation and see if it looks better.

[JesusJones]

Ok so your saying to just let it cook with no image showing or anything??

I've never done this and I wanna do this properly so help me out here with the fine details just a bit. Please.
So let me know witch of these two mothods is correct....


#1
Hook up an 8 volt source.
then just let it "cook"

Or

#2
Turn the unit on with the heater supply changed to 8 volts. And see if the image warms up?
If I do #2 I'm pretty sure all 3 heaters are hooked up in paralel to the voltage source.
So if I disconnect one heater. And leave the other 2 running. Will there voltage go up because of the drop of current, or is there a voltage regulator most likely?

Thanks for helping me out
Rudy

[radiotvnut]

Just disconnect the CRT board and connect an 8 volt source to the filament pins. Leave the set off and let it cook for 30 minutes or so. Then, remove the 8 V source, reconnect the CRT board, and see if the green tube is brighter.

[JesusJones]

ahhh Thanks very much
I will do this and report back later
Rudy

[mbates14]

Idea #4. Replace the CRT.

Take a flashlight and look at the end of the tube. youll see the filimetns going up into the cathode. if the cathode is very discolored from white, the CRT is deemed shot and needs replaced.

[JesusJones]

yea yea yea new tube I know. Easier to say than do

I'm just havin some fun with what I got.
If anyone wants to join in on the fun. Well then....

Should I ZAP it with a cap
Or Zap it with a light bulb???

Thanks
Rudy

P.S. I did the heater "cooking"
I set up a half wave rect and got 7.2-7.3 volts on the heaters. For about 25 minutes.
I tested it after and it seemed a little bit brighter.
Should I bump the voltage to 8 and try again. Or move on two some more brutal stuff.....

And I have a new tube coming but I may destroy the gel coolant when I put it in. SO I'm more than happy to do whatever to the tube already in there.

[andy]

000

[JesusJones]

There may be this resistor. But each crt neck does not have it's own resistor.

All three crts heaters are paralelled then connect to the Hv sweep board. On that board there is most likely a resistor that if bypassed would bump up the voltage. But it would do so to each crt. Causing the two better tubes to get worse alot faster.

I wanted to try powering the green crt with my homemade heater supply and then turning the projector on.
But running the other two crts would draw less current. Possibly bumping the other two tubes heater voltages much tooo high. Unless it is regulated??

As for old Tv's I do like them. But cannot store anymore than what I already have, and I only find TV's and other things in the garbage or at Garage sales. And since it's finally snowing today. I doubt I'll be picking anything new up till next year. So a CRT tester for me at this point would not be a very wise investment.
Rudy

[radiotvnut]

CRT testers will probably get even cheaper by next year. I will agree that if you plan to fix TV's, it would be well worth you buying one. I can't tell you how many TV's I've brought back to life by rejuvenating the CRT. These sets would have otherwise gone to the trash heap.

[JesusJones]

Ok I have read about this a fair bit.

I plan on using a 250 volt source and a 5 K resistor to make a 50 ma surge across the cathode.

Apparently 40 ma is the lowest used and it goes all the way up to 110 ma.

Two, Three second burts of this should do some sort of trick.

Sound good?

[JesusJones]

Ok i tried blasting it using the 250 volt power supply.. Heres how things went.

I hooked up the cathode and G2 when I did this.

I used my ammeter to veiw current and well...

Not much happened...The tube took the 30 ma. There was no purple glowing in the crt neck or anything. I gave it a couple shots of this then set it back up.

The green was still the same

I tried again! This time with only 2 k inbetween. Should have been nearly .125 amps. Current reached maybe 50 on my meter and that ended that.

The green is still the same no better or worse.

Anyone have some suggestions
thanks
Rudy

[JesusJones]

D'oh!

I shocked the wrong pin! I'll be back when I get the real results

Tried shocking what definatley must have been G2 an no current flowed at all. I'm confused to say the least...
Also how can I tell witch pin is wich. I know you actually have to look at where the wires go but I am not to familiar with what and where all the parts are.

_____
____ |
| x | |
| x | |
| x | |

Not that my picture makes much sense but here it goes....The xxx's are the heater. The iner cyclinder Which I cannot see (I assume it's there) Is what I am using as cathode(A fine wire goes between the larger outer shell and the heater wires). And the large outer shell I was using as G2. Sound right?

P.S. The picture is drawn with the left side cut off so it would be easier to draw.

Thanks
Rudy

[JesusJones]

Oh by the way

THE GREEN IS WORKING
IT"S WORKING
IT'S WORKING

HA!

[markdi]

very kool

I am happy with you.

[radiotvnut]

I'm glad you got it working. Just be aware that rejuvenation is a "hit or a miss". It may run for a year or more; or, it may crap out tomorrow. At least you know for sure that the tube was the problem and you can buy some time before having to replace that tube.