Westinghouse TV no picture : Strip or fix?

[wa2ise]

Originally Posted by electroking

You're right, and this brings a question. A transformer type set designed
for 25-Hz will work fine on 60-Hz, with only improved filtering. What about
a voltage-doubler set like this one?

It would also have improved filtering, as the filter caps are approx twice the size needed.

[electroking]

Originally Posted by JesusJones

Damn wish I had looked here an hour ago hahaha.
I just ordered all the caps by tediously looking inside and turning them and what not. But it's all good. And thanks for the schematic. Hopefully most of the voltages are near spec. I can't wait for those caps to get here. I'll tell you guys what happens as soon as I do.
And I"m pretty sure this set has two Chokes. And it also says on the back it's meant for 60hz.
I can't wait
Rudy

Hello again,

Hope the schematic is readable. I can read the posted images on my screen,
but printing yields marginal text for me. Il you look at the chassis layout
(second image in post 57 above), you will see the chokes on the left
side, L-500 and L-501, the latter for 25-Hz only. On the picture you posted
earlier, I can only see L-500. By the way, you could trace the wiring to
this choke and check with your ohmmeter to make sure it is not open.
The nominal resistance (36 ohms) is given on the schematic.

T-301 near the top looks similar, but is the audio output transformer.
Good luck.

[JesusJones]

I know I have checked one choke. It came in at 39 ohms. The other one is closer to the middle(guess you can't see it in the pic), then yes there is a small trans for the audio output.

Tomorow it's all getting checked and the caps I ordered should be in. So the final word on this TV should be up tomorow. Exciting stuff

[electroking]

What may look like a choke is the vertical output transformer (T-400). It is
shown at the right of V-15 on the schematic. Next to it on the schematic is
L-400, the vertical sweep coil assembly part of the deflection yoke on the
CRT neck. The deflection yoke also contain the horizontal sweep coil assembly
(L-401) shown at the bottom right of the schematic.

[JesusJones]

OMG I got 300+ volts. But it scared me to let the tubes fully warm up because this 300 volts was higher than the original capacitor rating. Which was just 300v. Any suggestions on resistors to put in series with the diodes to lower this. I know I have some 25 ohmers kickin around.
I wanna see this thing glow!

[nasadowsk]

If it's slightly higher (say, 320 - 340), and starts going down as the set heats up, it's ok - those caps have a 'surge' rating.

Or, you could get a Variac

[JesusJones]

Well I let it warm up fully(after I put in a 25 ohm resistor). And there was SOUND
Yet still no picture. BUT I could definatley hear it sweeping.( The hissing ringing sound you get with all TV's)
But this is no surprise to me as I've only replaced 2 of the 4 large electrolytics. I was just eager, and I know its bad, but I couldn't resist.

So yea that's about it for now. Just keeping all you guys up to date.

And as for the screen not lighting up. Does everyone still think it is because of the caps or is it possibly dead?

[electroking]

Hello again,

Great progress indeed!

Here are a few things to consider, regarding the picture.

You must have high-voltage on the CRT second anode (the terminal on the
side of the CRT with a funny cable ending in a round piece of rubber-like material).
Testing for high-voltage without a HV probe can be tricky, but there are a number
of simple things you can check. You said you tested most of the tubes. Did
that include the HV rectifier inside the metal cage? With power off, and chassis
DISCONNECTED from the line, you can remove the cover of the cage, undo the
top cap of the 1X2A tube and pull it. Be careful when setting your tube tester,
this heater takes a very low voltage.

Also, in the third picture of your post number 19, you showed the rear side of
the horizontal output (=flyback) transformer. I notice that a big yellow capacitor
has traces of heating on it, it would be a good idea to replace it. There is also
another capacitor, a red tubular one with capacitance unreadable, connected
to the damper tube (12AX4GTA). See the resistor alongside this capacitor?
Il looks like it took a beating, the color bands are unreadable. It would be a good
idea to check this against the schematic and replace if necessary.

You may also want to take voltage readings at the CRT electrodes. If you trace
the wires from the CRT socket to the chassis, you should be able to find in particular
those that go to the cathode (pin 11) and grid 1 (pin 2). On the cathode,
according to the schematic, you should get +113 V, and on the grid you should
have somewhere between roughly 0 and +120 V, depending on the brightness
setting.

Also, be sure to measure the cathode voltage on the 12C5 audio output tube
(point V). This tube operates as a voltage divider to provide plate voltage
to many stages in the receiver. The nominal value shown on the schematic
is 132 V. This will confirm that most of the stages are drawing the correct
amount of current.

Good luck, keep the news coming!

[ALTEC9846-8A]

REmember the crt acts like a capacitor at the h.v. spot.Take a srewdriver and short to gnd that spot to discharge the charge held by the crt.

[electroking]

Originally Posted by ALTEC9846-8A

REmember the crt acts like a capacitor at the h.v. spot.Take a srewdriver and short to gnd that spot to discharge the charge held by the crt.

Good advice, just be sure to slip the tool gently under the high-voltage
insulator on the CRT, in order not to scratch the glass.

It would be best to first attach a jumper to the screwdriver, connect
the other end of the jumper to the chassis, and then touch the HV
terminal with the screwdriver.

[JesusJones]

Wellll I did all the tests electroking told me to do.
The 12c5 at cathode has +122v after warm up.
Pin 11 of the picture tube has 120-140 volts depending on channel.( Tuned or not tuned)
pin 2 goes up to 70 volts then down to zero as you adjust brightness.(not exactly 120v)
The resistor you mentioned I also suspected of being shot. But with very close inspection you can still see a brown then green then brown stripe. JUST BARELY. And the resistor reads 127 ohms on my meter(Which is not the greatest, but it works) so it's kinda close. But maybe not close enough?
The capacitor you saw I will replace momentarilly I did order some of those charred brown looking ones. Also the one paper cap in the tuner circuit.

Oh and I almost forgot. I do think I tested the HV rect tube when i tested all the others. I'm pretty sure it was within spec. And I know that I am always very careful pulling things like that out and putting then back in. SO I'm pretty sure that tube is fine but if you insist I check again I will be glad to.

And the HV is in the thousands I am guessing. So it would probably blow my meter which only goes to 1000vdc.

Could those little paper caps really be stopping any picture from being produced?

I also have one more electrolytic I should change. But I dont have the exact replacement. It is 200 mfd. and I Have 100 and some 30's. I think I may just strap them all together till I get close. It's better than nothing right?

Rudy

P.S. What actually makes the picture tube glow. With these voltages should I at least have a dot on the screen already?

[electroking]

Hello again,

To answer your question, if you have correct voltages on the electron-gun
electrodes, you should get a spot on the screen, but only if HV is present.
Your measurements show positive results, but there are many more things
to check, and because of the distance I cannot think of all of them at once!

In my opinion, the next step would be to measure the cathode voltage
on the 12BQ6 (or 12CU6) horizontal output tube (pin 8). The schematic gives 3.6 V
across the 33-ohm resistor, which corresponds to about 110 mA cathode
current.

It gets hard to go much further without an oscilloscope, but let's see what
you get. Bye for now.

P.S.: for anyone just joining this thread, schematic is in post 56 above. Regards.

P.P.S.: also check voltage on G2 (pin 10) of CRT, this will tell whether the boost
B+ generated by the horizontal ouptut circuit is present. Be careful to use the
highest range on your multimeter.

[JesusJones]

Ineteresting.....Because there is no 33 ohm resistor hooked up to that tube. And the voltage I got across pin 8's resistor was only .5 volts. This is the one that you said looked burnt or possibly dead. and it supposed to be 150 ohms according to it's bands.
I will go look some more and also test the voltage at from chassis to pin 8 and see if i get the 3.6 volts it should have.
And I looked at the screen and I'm not seeing any bright spot. And I can clearly hear the buzz/whinning sound most crt tv's make. Is this a good sign the ht is working?

Cause if so..It brings me back to my original thoughts which is that the pic tube is dead......But I really hope not.

I did the test from pin 8 to chassis . Only .5 volts .....

Little more info: I made the other 200uf and put it in. Then replaced that yellow cap which was burnt. And still no picture.
And this scared me. But every now and then I hear arcing.....!This is during tube warm up and I always shut it off asap! It may be from my shabby work I did putting in the caps but boy was it scary. Usually it doesn't though

[electroking]

Originally Posted by JesusJones

Ineteresting.....Because there is no 33 ohm resistor hooked up to that tube. And the voltage I got across pin 8's resistor was only .5 volts. This is the one that you said looked burnt or possibly dead. and it supposed to be 150 ohms according to it's bands.
I will go look some more and also test the voltage at from chassis to pin 8 and see if i get the 3.6 volts it should have.
And I looked at the screen and I'm not seeing any bright spot. And I can clearly hear the buzz/whinning sound most crt tv's make. Is this a good sign the ht is working?

Cause if so..It brings me back to my original thoughts which is that the pic tube is dead......But I really hope not.

I did the test frompin 8 to chassis . Only .5 volts .....

All right, let's not get confused here. Looking at the schematic around V-18,
I see:

cathode (pin 8) connected to ground through a parallel network of
R-453 (33 0hms) and C-439 (.1 mfd 200 V);

grid 1 (pin 5) connected to PC board through R-450 (150 ohms);

grid 2 (pin 4) connected to width control through R-454 (680
ohms).

If you found a 150 ohm from cathode to ground, that is strange, and
probably the sign of a previous botched repair. But maybe the 150 ohm
resistor you saw was R-450 above. Just as a reminder, the pins are
counted clockwise as seen from the bottom, starting from the indexing
tab.

The buzz means that the horizontal oscillator is running and probably
being amplified by the output tube, but until the circuit is fully functional,
no normal operation will happen. If you get the chance, please do check
the G2 voltage of the CRT. As I told you, this is fed from the boost
voltage generated by the damper tube (V-20), and is an indication of correct
operation of the sweep circuit. I bet this is not OK at present.
Good luck.

[JesusJones]

Sounds good. Gimmi half an hour maybe less

Ok and I have checked checked and rechecked pin 8. It does have a .1 mfd cap but its definatley a cap that has brown green brown bands on it. And it measures in at 126 ohms or so. It doesn't really look like it was put in by someone else, but who knows.

And another side not... There is a wire in the crt pins that connects two of them together. It looks like it is supposed to be there. And in the schem I thought I saw something that resembles this on the schematic so it may be right BUt just thought I'd put it out there. Its from pin 10 to pin 6 of the crt.

And you are onto something here. My meter gave me zero volts at pin 10 of the crt. 0v And the damper tubes seems to go through a variable resistor before reaching the crt, if I am right. This is for adjustment for vertical height located at the back of the TV.

"This brings me back to arcing. It seems the damper tube is connected to the same hv coil as the 1x2b.(I'm guessing that's how it boosts it) When I had the cage off I saw this transformer coil w/e it is. It sorta looked chipped The rubbery coating sorta flaked off. Maybe the arcing happened there somewhere causing some sorta problem with the damper tube causing my 0 voltage at G2. This is just a huge guess but I noticed there connected through this so it could be true. " This is a BIG GUESS