Westinghouse H14T17 Restoration/Questions
 

Picked this Westinghouse 14 inch "portable" set from 57'
Few questions as I'm still new to the field of television repair (patience appreciated):D

There's a 4.7 ohm resistor placed right before the half wave rectifier that's gone bad. According to the datasheet, it should be 1/2w although it looks like a much higher wattage resistor. Is this a typo or am I reading this wrong?

Datasheet and resistor(R82)
http://i50.photobucket.com/albums/f3...psiponvcba.jpg

Looks to be in the 5-20w range. Word to the wise Sam's are full of typos, and even the good ones are not the last word... There were often many production changes throughout the life of a chassis... Sam's are usually a snapshot of one. Whether it was the first, last, best, or worst is not usually known.

When you restore a set it is best to go by the original parts instead of the schematic... granted if someone has worked on it before you and hacked up the wiring or made questionable replacements, or if the originals are damaged beyond identification the schematic is your best guide.

That resistor is probably for current limiting the selenium rect. Resistance is not critical ( wattage will be though) and may be increased to compensate for the reduced voltage drop across the diode that you're presumaby replacing the selenium with.

The preceding was a message from your friendly neighborhood insomniac TV restorer.

You'd be correct in assuming that, is it just trial and error to see what gets the proper voltages? I had heard that each plate on the selenium drops somewhere between 1 and 2 volts. Is that a good ballpark?

Also, the 4.7ohm resistor was before the selenium, could the value be added to the resistor or would it have to be placed after the new diode?

That is a fusable resistor and they act like a slow blow fuse. You can sometimes find them on the auction site or replace with a fuse and a resistor. I would use a 10 watt resistor if it were mine.

Gregb

4.7 ohm 5 watt

So I replaced the 4.7 ohm resistor with a 10watt resistor of the same value. Unfortunately it's blowing the resistor, any recommendations on how to isolate the problem?

Blowing the resistor or just getting really hot? Hot would be normal, burning it out would probably indicate a shorted filter cap.

It burned out, I checked the caps prior to putting them in, and now they've fried as well. So the real question is why did the filter caps burn out when they're brand new? Is this something I should troubleshoot further before putting in new caps?

Check that you had the polarity to the filter cans correct, backwards or too many volts is about all that could kill them.

Did they smoke or get hot?

New diode?:saywhat: Did you shunt the selenium with a Si diode? If so, is the polarity correct? (Banded end goes to the 'downstream' end of the selenium, usually marked '+'.)

When using a Si diode, the selenium can be left in place but with the 'upstream' end disconnected so the selenium's out-of-circuit.

Well that'll about do it, in my excitement to install it I flipped the whole mount backwards, diode and all.

Once I purchase new caps, I'll do a power test and see how it goes. Stay posted for updates and likewise, more questions.

Thanks all,
Zach

If the 4.7Ω 'fuse' resistor popped quickly enough, there's a chance you didn't kill the caps.

Good idea to replace at least the first one anyway, since it wouda took the hardest hit.

Well success, replaced the diode and filter capacitors. Set warmed up with no problems, still no raster, although I can hear the flyback's distinctive whine.

Found that the 1X2B was faulty and replaced it with a working tube.(thought I had tested all of these :dunno:) Alas, still no raster. Checked the damper tube along with surrounding connections, and main voltages appear within 1-2 volts.

Finally pulled out my capacitor checker and tested the single 4kv 160pF ceramic capacitor in the flyback circuit just to find that it had failed. Well, time to order parts, it's always one thing or another

Anyone know where I can purchase caps like this?
Cheers,
Zach

Are you getting any high voltage to the top of the 1X2? Just touch the tip of a (well insulated) ungrounded screwdriver to it and you should draw an arc.


I have this same set by the way, it's a Raymond Lowey design.

http://www.vintagetvsets.com/images/lowey1.jpg

Yes, it does arc though not very far, and it's a fun set, good learning process for me

So the brightness control that's supposed to be 100k ohms is now about 800k, any idea where to find a replacement as it is also connected to the vert. hold and vert. linearity pots?

Well, I tested the CRT, which produced good emissions after a long warm up from it's 50 year nap. The HV section is producing the needed 10kv for the annode, but still no raster nor indication of life. Any ideas?

Thanks,
Zach

Does it have an Ion trap on the neck of the tube? It might need adjusted.

Would this Ion trap work? It didn't have one but I had a spare from a salvaged crossly TV (10BP4)

Attachment 197062
Attachment 197063

What is the crt number?

jr

It's a 14NP4A

The tube does require an ion trap:

https://frank.pocnet.net/sheets/201/1/14NP4.pdf

I have never seen one that looks like the one you pictured... guess it can't hurt to try it. :scratch2:

jr

It requires a single field trap and that's a double. Still might work enough to give you something, you could also try removing one of the magnets from that trap.

It's theoretically possible to damage a tube by running it with a misadjusted trap, keep the brightness control turned down about halfway while experimenting with the trap.

If you get a raster adjust the trap for the maximum brightness and focus.

Great News! After finding an ion trap suitable for the TV, I hesitantly powered the set on and hooked up my DAC hoping for the best. After adjusting the raster for maximum brightness, I then proceeded to mess with all the controls and received this picture.
Attachment 197064
Thanks for everyone's help with this, this has been a fun first TV repair.
Now to just fix the sound problems, Vertical Compression, and reverse the yoke

Thanks all,
Zach

Quick question, the image appears to be shifted downwards, making it difficult to see the bottom text, and a black bar at the top. I've checked all the resistors in the vertical Linearity circuit, replaced two but still no solution. The raster fills the screen, but TV programs do not. Any ideas where this could be stemming from?

Attachment 197069
(The rest of the screen is fine, my camera picks it up weird. Picture is also upside down)

Does the yoke have positioning tabs at the rear like those shown in the Marconi TV thread? ( shiny tabs @ 11 o clock and 9 o clock position on the rear of the yoke).

http://www.videokarma.org/attachment...7&d=1526186137

Rotate the two tabs together to change position... change the distance between the two tabs to adjust the strength of the position magnet.

jr

Have you heard of Letterbox movies/TV shows? All newer HD shows are 16x9 aspect ratio and most sources convert them to 4x3 aspect ratio by letterboxing the content...It is a fact of life when trying to fit a rectangular show into a square hole these days.

Yes, thanks, I was able to properly center the image, although the part that covered the yoke is almost disintegrated.


Yes, although I adjusted this tv so that there isn't any space surrounding the newer pictures, I figured that a few cut off areas aren't gonna hurt my viewing experience.

Thanks all,
Zach