Entertainment Center: TVs, Stereos, VCRs and DVDs - Zenith 52" flashing

I am working on a zenith 52" rear projection, model 5255xxxx, occasionally the picture will start to flash, showing very powerful blues, reds,greens.. almost a negative image. if you turn the power off then back on the set will operate normally, this is not limited to just 1 crt, its all 3, it happens randomly. any info is greatly appreciated.

Thank You.

Good evening, Sentry6:

That series of Zenith has, as I recall, a problem with leakage in the High Voltage/focus block. It shoulds like the block is breaking down and causing the high voltage to oscillate.

Not good! Be aware that if you continue to run this set, the problem can damage the projection tubes.


Smokey ;)

smokey, thank you for the reply, yes these sets have alot of problems with the focus devider block!! and suprisingly i replace it a year ago, and i will note the crt's are only 3 weeks old, so on that note i will look to see if i have a spare focus divider block around and see if that isnt the problem. thank you for the advice. by the way, doesnt this set have a module with an adjustment for the volatage oscillation?. also would you be able to recommend any online suppliers for parts for this set, such as the focus block etc, parts are becoming hard to find.

Thank You
Sentry6

Good Morning, Sentry6:

I don't recall an adjustment for oscillations. Oscillations start when there is a feedback loop and this is why I hit on the HV
Focus block. They had some leakage problems.

Best place so far for hard to get parts for Zenith has been
Union Electronics http://www.unionel.com

They have been very helpful in the past and have an 800 number to call.


Smokey ;)

Smokey just wanted to thank you for your help, i just placed an order for that part, good place to start not worth chancing the new tubes.

Again thank you
Sentry6

Thank you for the kind words and thank you for using DoItYourself.com.

And, let us know how you make out.


Smokey ;)

well against my advice the customer (who also is a friend) has been running the set without the new FD block, last night there was a loud pop from the rear, and a very bad smell, the convergence went all over the place, and the green has no focus at the bottom of the screen, and the pin is way off(green). the smell is like a gasoline smell, maybe capacitor or transformer?, the weird part is the smell appears to be coming from the green crt. any advice is appreciated, i should have the FD block very soon. but now im not sure what other damage has been caused.

Thank You!!
Sentry6

Sounds like the HV/Focus block blew. Nasty mess! I don't envy you your job. Check the HV caps in the circuit. When the block goes, they give up their lives in a hurry.

Smokey ;)

smokey again thank you for the reply, ive been checking the HV boards with no sign of damage, again like i said the smell is coming from the green crt, that is what has got me baffled... maybe it overheated the crt?

Thanks again!!
Sentry6

Very possibly a shorted deflection transformer (yoke). I would still back track it to the HV/Focus block.

Very possible that this failure snuffed the green projection tube, also.

Smokey ;)

hey smokey thanks again, i have a spare parts set (front projector), yokes and few other parts are the same, im going to replace the green yoke, install the new FD block if it ever shows up, and put the new green crt in ( good thing i hadnt installed it yet!! :) ). and keep my fingers crossed.

Thanks Sentry6

ok im probably driving everyone crazy by now, almost done with this old clunker!! follow up, finally got my fd block!!. pulled the green tube out, as soon as i slid the yoke off, what do u know!! the tube was leaking into the yoke!! (zenith crt's dont leak do they?? :) ). any how.. i have a set of yokes from a 1 year newer set but its a front projector, the front projector uses the same exact crt's, but the yokes are slightly different in exterior looks only. connections and labels are all the same, the part number are different slightly, can someone tell me if they are just updated (newer) or not. (my zenith distributer said "of course there not, there different part numbers") but......

original rear proj. yoke: 95-4038-01
newer front proj yoke: 95-4038-02

(polls maybe reversed? no... function of the floor/cel. board..)

Thanks again for all your help

Sentry6

Go to http://www.unionel.com

This is Union Electronics and they are an excellent parts source.
Use their 800 number and talk to customer service. They can tell you if the two parts are compatible or can at least offer you the correct part.


Smokey:

smokey thanks again, i called them, they were very helpful and friendly!!. the yokes -00 and -01 are the same except for length of the wires. any how thought i would let you know the set is back up and running!!.

i do have another problem, at the top of the screen there is a 1 inch strip from left to right perfectly straight that has a green tint to it. very noticable on a white background.

and also a question... the mirror, i have tried the dry cloth method.. windex everything, the more i try and clean it the worse i make it.. almost like there is a film on it.. can u suggest the best way to clean it?.

As Always thank you!!

Sentry6

The yoke is out of alignment on the green tube. Try moving it forward or backward a little to correct the purity.

Cleaning the lenses and the screen need a special cleaner. Smokey recommends this stuff:

http://www.tritronicsinc.com/proclean.html

Smokey ;)

i will order a bottle, thank you, and i will try as u suggested on the yoke, i just wanted to note that this is the second yoke on the green and 2nd crt, with either crt or yoke, i have had this green stip at the top... the overscan is also right on the money.,..

Thanks!!
Sentry6

ok guys, back to the original problem, with the new FD Block in the set has been running for a while, it just started to do the original problem!! theres still a volatage oscilation, i wan to ad more info, when this problem occurs, you shut it off then back on again, all is fine, but the blue tube takes alot longer then the others to come back on, i want to ad this set did not have this problem till i replace the crt's, i dont want to think there is a problem with the blue crt, especially sence video display corp rebuilt them and from what i understand they are a very reliavle company. sence i had a shorted yoke (green) and possibly bad FD block, should i again start looking at a bad HV module?

Thanks again guys for your help!! god! i thought i was done with this thing :) im gald you guys have all had patience with me!!

Sentry6

i also want to note i have ALOT of spare parts for late 80's early 90's proj sets front and rear, any of you guys need a part just yell (or e-mail :) ).

Any chance the blue CRT is gassy?


Smokey ;)

please describe gassy, and how i can tell, my experience with tv's is limited please be patient with me :) what i know of "gassy" is that the signs will be poor focus, color bleed through in neck, am i correct?.

im thinking out loud here, when the voltage starts to oscillate out of sync, the picture goes crappy, i turn power off/on and its back to normal, except a 2 - 5 second delay for blue to power up, now would this be a problem in the crt, or the video? could the sweep module may have become damaged? i know there is a sync oscillation circuit on the sweep module. again just thinking out loud.... also when the set is turned on cold, the blue crt comes up the same time as the others

oh and the set is now mine, so its really my problem now :(

again thank you, u guys have been great!!
Sentry6

When I speak of "gassy", I am referring to air in a vacuum area.

I know you said you have replaced the tubes but the tubes you are using may be rebuilt units. If they didn't delete all the air from the tube after it was closed up, you could well have a "gassy" condition.

Smokey ;)

smokey thanks again

is there a test to detect, or a sign of a "gassy" tube? i have a spare blue crt (burnt image in it), works fine... ill put that in and see if it still does it.

also i want to pick your brain some more, the color is a little washed, the g2's are adjusted per instructions in the tech man, and grey scale is perfect, to get good color i need to crank the user color level almost to max.... video drive?

you guys have a great forum! very helpful thank you.

does this site operate on donations?

Sentry6

Good evening, Sentry6:

Let's discuss your last post:
is there a test to detect, or a sign of a "gassy" tube? i have a spare blue crt (burnt image in it), works fine... ill put that in and see if it still does it.
****************************************************
Smokey says: Good choice.
***************************************************

also i want to pick your brain some more, the color is a little washed, the g2's are adjusted per instructions in the tech man, and grey scale is perfect, to get good color i need to crank the user color level almost to max.... video drive?
***************************************************
Smokey say: G2's only set brightness. What you are talking about is "Contrast" or video level. If you want to correct this problem, you have to look at AGC, Video Preamplifiers, and Video Amplifiers (in that order!)
***************************************************

you guys have a great forum! very helpful thank you.

does this site operate on donations?
***************************************************

We thank you for your thank you. And, no, we don't accept donations. We are all volunteers working across the world to bring a better life to the common man needing our assistance.

If you feel the need to offer money, please send it to your favorite charity.

Smokey ;)

oscillation

smokey you nailed that one down!!, I replaced the blue crt, and now the set works fine. been running it for 3 days now, and have not had that same problem. ;)

*************************************

green tinted line

come to find out the source i was using was the problem, changed to dvd from satellite, and its gone, tested satellite receiver on another set... its the problem. :rolleyes:

*************************************
*************************************
:(
question 1

when ever the set is turned on it goes to "new installation setup" its only supposed to do this when the set is new, or has been unplugged for a long period of time, any ideas on how to get rid of it?
**************************************************
You have to get into the menues to disable this function.
Smokey
*************************************

question 2

picture quality does not seem to be all that great, watching a dvd it looks like im watching cable.. alot of noise in the pictute and if u look very closely can just see a slight HORZ. jitter. and there is also a thin line from top to bottom on the left side of the picture, its there no matter what input i use, it apears to be part of the signal.
***************************************************
Sounds like a blanking problem.
Smokey
*************************************

As always!! any help is GREATLY appreciated :)
Thank You
Sentry6
****************************************************
We'll be around if you need us.

Smokey ;)

See answers above.

question 1

thank you, that's easy.

question 2

what would you suggest to fix this problem?

Sentry6

I suggest you check the blanking amplifier and find out if it is clipping sync. The board may be bad and may need replacing. You have found a lot wrong with this old set and could well be another problem.

Have you checked the power supply voltages for ripple? How about regulation? All possibilities here.

Also, this thread is becoming too long so I am going to close it. If you need further assistance, start a new thread. We have to do this because the server space only allows so many entries before it starts to get cranky.

Smokey ;)