Westinghouse TV no picture : Strip or fix?

[electroking]

Hello again,

Maybe the cathode resistor is correct after all, but if you only measure 0.5 V across
it, it means current is only 4 mA, definitely low.

(What I meant here is that sometimes component values are changed in production).

The jumper you see at the CRT pins connects the focus pin (6) to either pin 2 or
10, as selected for best results when installing the CRT. This is no problem.

I think I will call it quits for today, don't give up hope, the diagnosis will come up,
and the cure will follow! Let me know what you find out, but as I just said I won't
be replying until tomorrow. If anyone else wants to join in, I trust you're welcome.

[JesusJones]

Yea if any one has ideas or things for me to check just say it. Nothing sounds stupid to me and it's all worth checking.
And ElectroKing your help is greatly appreciated. And yes we will tackle this problem another day still

Oh and if anyone is having trouble reading the schematic open it in paint and invert the colours. It helps.

New Info: The damper tube produces 350 some odd volts. Then it goes down through a 270k resistor(that reads 350k on my meter) and goes directly to G2(pin 10) of the CRT. At the Crt the voltage on G2 is 250 volts.
Tell me what you guys think. I must have fudged my first test.

[electroking]

Two more ideas, and I promise I close Audiokarma for the night!

1 - Capacitor C-440 (0.068 mfd, 600 V) just below the damper tube on the
schematic is a filter for the boost voltage rectified by the damper. If
it leaks, it may lead to the loss in voltage observed. This capacitor
has a low capacitance here because the frequency is high (15 kHz, not
60 or 120 Hz as in the power supply).

2 - With power off, the main winding of the flyback could be tested for continuity.

From top to bottom, the terminal numbers and resistance values are:

7 (cap of HV rectifier)
460 ohms
6 (cap of H ouptut tube)
24 omhs
5 (cathode of damper)
4 ohms
9 (end of winding in deflection yoke)
31 ohms
3 (end of C-440 not connected to plate of damper)

Note that the first section has higher resistance because it has many turns;
it is the part of the transformer that generates the high voltage pulses
to be rectified by the 1X2.

If the readings are approximately OK, the transformer is probably still good, even
though there may have been some arcing in the past.

Good night.

[nasadowsk]

Do you hear a raspy low frequency sound? Like a little motorboat motor in there? If so, the vertical is working and you no doubt have at least functional horizontal.

Don't overlook the obvious - the brightness might be down on the TV

You can't, unless you can easily (safely!) see up into the HV rect, see it glow normally. BTW, if you get an HV *pop* when you discharge the CRT, you no doubt have HV, which is going to be on the order of 12,000 - 16,000 or so. If you've got a hissing - like a gas leak - coming from the HV box, you have HV, and a good amount. Shut the set, discharge it well, and CLEAN THE HV BOX. Dirt might cause leakage, arcs, flashovers, and scary things that can be bad for the set.

Don't ever measure the horizontal output tube's plate - there's a big pulse riding on it.

BTW, sounds like you're gonna need an oscilloscope - get one that can go over 10mhz. They're cheap and a great investment.

[JesusJones]

Ahhhh I was checking those resistances earlier. They seemed alright but I did not check from 7-6 or the nine one. So I will do this.

And this has been driving me nuts. On the schematic you sent me v-2 is on the left and v1 is on the right.
But on the back of the TV in its tube diagram V1 is on the left and v2 on the right. SO I checked the tubes and surley enough they were as the schematic you sent me v2 left v1 right. BUt on the back of the tv (Which had to of been right for this model) It is reversed. SO if the tv's original cover does not lie. These tubes are reversed. And need switching.
I will put a picture of the tv's diagram momentarily.
Also one of these tubes was a weak one. And if they really are in reverse maybe it is because the heater voltages were different causing earlier melt down.


Hmmmm... no motorboat noises. But I will listen harder.
Haha I also thought the brightness might be the cause. So I fiddled with all the controls and it just wouldn't work.(Bummer)
But cleaning it sounds like a good idea. It was very dusty. I'll blow it out tomorrow when I am checking the coil resistances

Pictures in 2 minutes

[JesusJones]

check it out

Its blury but you can still see my point. It is reversed. Should I switch these tubes around?

The other schematic showing how my tubes were installed is on page 4 of this forum.

[electroking]

Picture 2 in post 16 shows a big hole in place of the tuner in the upper left corner
of the chassis, because the tuner is mounted on the front panel in your particular
set. The 5AT8 is the tube that goes nearest the tuning knob. So I assume there
is some kind of discrepancy between the rear cover and the actual layout. Tell
me if this sounds OK.

All the tubes use the same heating current (600 mA), so reversing them is
unlikely to have caused damage.

[JesusJones]

Yes you are dead on. Its mounted near the front with all the knobs. And it was in correct. I tried switching them and no sound. So I guess that solves that.

Oh and after letting it warm up in the dark there was one tube with a blue cloud. But it went away(very bottom right) And I smelt something burning. Not burning insanley. But I can smell it. And I noticed a resistor that has black goo near the leads that come out of it.(This was near where I thought the smell was) Its bands were green blue brown. And it has 650 ohms of resistance instead of 560.

I will turn it on and smell some more...

The smell is definatley coming from the middle. And this resistor is almost the only thing there. It is hooked up between the two large upper capacitors.
I also tried a trick some one mentioned at the beggining of this forum. A fluorescent bulb near the ht line that goes to the side of the CRT. The bulb did not glow

[electroking]

I should have thought about it, if you had sound, the tuner could not have the
tubes installed wrong!

By all means try to identify this resistor: to what tube pins or other points is it connected?

P.S.: there's much more fun in troubleshooting than in demolishing, don't you think?

[JesusJones]

Ha ha ha yes. This is definatley more fun that putting another pile of junk aside for me to use in the future. I can hardly sleep trying to figure this thing out.
In other words. "I just can't get enough, just can't....."


and more specifically the resistor goes from 30 mfd to the 200mfd. These are the larger ones at the top.

[electroking]

Hello again,

Regarding this 560-ohm resistor, could that be R-451, connected to L-400,
at the right of V-15? If C-443 (an electrolytic) is leaking, it may cause
the resistor to heat up.

How many hours has it been since I told you I was quitting for the day?
Good night!

[electroking]

So it is R-451, but the parts on the schematic are far apart:

The 30 mfd is C-443 as I told you.

The 200 mfd is C-502, the upper capacitor at the output of the filter choke
in the power supply. You can follow the long wire marked 264 V running at the
bottom of the schematic.

[JesusJones]

Tooo many. hahaha I am quiting to. And I will have something to say tomorrow. I think about this stuff in my sleep.

More tomorrow folks!

[Boobtubeman]

hehehe a tech pow wow... love it

Steve

[JesusJones]

So I was trying to look up if the crt could be dead. And have no glow, picture or anything. I never found my answer, but saw some stuff on LCD repair. And I remembered a 5 inch LCD I bought in gr. 7-8. Of coarse though it stopped working. Much too soon of coarse(maybe in a year or two). And it cost 200$. I tried my best to asses the problem at the time. Blown backlight dead something else expensive(and probably non existent for that lcd).
It was a bummer. I begged my parents for it. And they spent that 200$ for me. And then one day it just didn't work.....
(I didn't even own a ps1)

Well today I was still in the fixin mood. So with all my new knowledge since gr 8 I went to tackle it again. This time I did not assume it was broken. I assumed something simple had blown like a diode that blows when you hook up polarities backwards. Nope all diodes good though.(This is also all surface mount stuff...way waaaay smaller than tubes smaller than these letters you are reading) And then I saw it. Something not called R-37 or C-12 or T-1 (Resistor Cap and Transformer) THERE WAS AN F-1, A FUUUSE!!! I shorted it out with some metal and it came back to life.And I almost s@!T my pants.

So the moral of the story is. Don't throw stuff away you think is done for. You might just figure it out with all your new tricks and knowledge.... 5 years later....

AND I FIXED IT BOOYAH!
made me feel good

now back to 60's technology

I found a perfect (Wire wound I think) 560 ohm 2 watt resistor. This is pure luck. But I'm gonna put it in there tomorrow.
And also I need reassurance that the picture tube is not dead. Even with all the progress so far a dot will not even show up on the screen....?

New Day,

Also I thought for sure I had H.V.. But after putting a fluorescent bulb near the H.V. And trying to discharge it twice and hearing no spark as I did it. I'm guessing the HV is gone. I checked all the resistances ElectroKing had mentioned they check out fine. So the problem does not lie there.

I'm going to replace all the film caps near the HV area and also that one 560 ohm resistor AND then check that the 1ax2b is properly connected to its socket. AAAANNND does anyone think a dirty faulty button connection (The little cap that connects to the top of the tubes) could be causing such a problem.

And the results of that were:

The 560 ohm resistor IS burning up. Something drawing current from that resistor is either underbiased or just not working right. But from the schematic I see it is hooked up to the plate of the vert d/f tube and this tube is not biased in any way, its cathode is just grounded. Any ideas?

HA! HA! HA! more news: The vert deflection tube is the same one I saw glowing blue yesterday night. In the bottom right. If that helps any