Sonora 50s metal portable - Page 5 - Videokarma.org TV - Video

bandersen · #61 12-25-2013, 03:00 AM

I stayed up late troubleshooting and it finally paid off.

First, I found this 8200 ohm power resistor was open. I cracked it open for a look inside and found a break in the wire towards one end.

The flyback was still making horrible squeals though so I fired up a scope. The waveforms are quite odd. There are bursts of 15kHz with long periods on no oscillation. Tweaking the horizontal hold and how wave shape controls improved it somewhat.

Eventually, I tracked the problem down to a bad 1N60 diode in the sync circuit. It was replaced with what I think is a 1N34.

That finally produced some HV so I hooked up the CRT. It took a long time to warm up since it's a .6A filament in a .45A string, but eventually a raster appeared.

Now I know why there was on ion trap magnet on the CRT. When it was rebuilt, they used a straight gun so it has a nice ion burn in the center

Shortly after I got the raster, I noticed a burning smell. Some sniffing led me to this fried resistor. I doubled checked my wiring and found I installed the 10uF capacitor backwards

Replacing those components gave me a stable raster so I hooked up a signal source. Clearly the horizontal is out of whack.

Fighting with the hold and waveshape controls got me a stable image. The burn isn't too noticeable if you don't think about it.

I expect the CRT would be even brighter and sharper with a proper 6.3 @ 0.6A filament supply, but I think that would also make the ion burn worse faster.

Not bad for such a simple set. Next I need to rig up some thing to hold the yoke in place. I think I can get by without the centering rings.

dieseljeep · #62 12-25-2013, 11:53 AM

The horizontal osc, afc circuit is sort of a knock-off of the RCA sychroguide design, even down to the .01 cap across the phasing coil.
I see one of the tube suppliers has "dollar days", where a lot of those odd 450ma tubes that your set uses are a buck each.
A good time to pick up more spares.

bandersen · #63 12-26-2013, 08:27 PM

Quote:

Originally Posted by paulg

I used to use ECHO rebuilt tubes.. He sometimes used the brand PRECISION tube.
He was a one-two man outfit on the Southside of Chicago - somewhere around 63rd and Kedzie I think.
He was very much the expert. The place was a fascinating workplace. Crude but effective. His tubes always turned out beautifully. He prided himself on how broadcasters would bring studio CRTs to him to rebuild.
He would write the date of pickup on the tube. He would give a warranty of "a year, a month and a day. " just to cover the tech's butt if he couldn't get the dud tube back in time... Quite a character. I learned a lot from him.

I wonder why he put a straight gun in this CRT ? Seems unlikely bent guns hard to get in the early 60s. Maybe it was just a mistake ?

I put an ad in the classifieds for a replacement.

Quote:

Originally Posted by dieseljeep

I see one of the tube suppliers has "dollar days", where a lot of those odd 450ma tubes that your set uses are a buck each. A good time to pick up more spares.

Which one ?

dieseljeep · #64 12-26-2013, 08:58 PM

Quote:

Originally Posted by bandersen

I wonder why he put a straight gun in this CRT ? Seems unlikely bent guns hard to get in the early 60s. Maybe it was just a mistake ?

I put an ad in the classifieds for a replacement.

Which one ?

I thought, that's where you ordered the 4BC5's for a buck each. The 6CL8's were $3.00 each.
I mentioned the firm before. ESRC, located in Florida.
In going to order a mess of the dollar specials, myself.

BTW, the prices are only good 'till 12/31/13.

bandersen · #65 12-26-2013, 09:23 PM

Nope, I got my tubes from an eBay seller for $1.25 each. I only have one other .45A set, but I may order more tubes from ESRC anyway. Can't let a good sale go to waste

Thanks for the tip.

http://www.esrcvacuumtubes.com/dollar_days.html

DavGoodlin · #66 12-26-2013, 09:57 PM

Nice troubleshooting.
Funny how an open sync diode (is that the clipper?) can let video in and screw up the sweep so bad it can really throw you off.

6he5tom · #67 01-05-2014, 04:16 PM

I have three of these sets in cream color with the Airline brand on them.

dieseljeep · #68 01-06-2014, 12:20 PM

Quote:

Originally Posted by bandersen

Nope, I got my tubes from an eBay seller for $1.25 each. I only have one other .45A set, but I may order more tubes from ESRC anyway. Can't let a good sale go to waste

Thanks for the tip.

http://www.esrcvacuumtubes.com/dollar_days.html

They extended the offer until 6/30/14. I guess they have so many of these losers, that they're cluttering up the place.

bandersen · #69 01-18-2014, 05:42 PM

Here's an Airline on ebay http://r.ebay.com/P6QsqU

dieseljeep · #70 01-18-2014, 06:54 PM

Quote:

Originally Posted by bandersen

Here's an Airline on ebay http://r.ebay.com/P6QsqU

$200 for that rust bucket!
I'd be hard pressed to pay 1% of the asking. I like the white painted stove handle.
The reason the volume and contrast knobs are so large, as they had to be removed to adjust the service controls. Vertical lin and ht, etc.

sooznd · #71 01-18-2014, 07:36 PM

banderson
My family had two of those metal Admiral TV's when I was a kid, one was red and white and I think the other one was 2 tone brown or copper.
When I got married, I got the red & white one. Wish I still had it.

bandersen · #72 01-18-2014, 09:20 PM

Those Admirals do show up on ebay and craigslist so you might be able to find one.

bandersen · #73 01-22-2014, 04:07 PM

I decided to put the set back together while I wait and see if any parts sets or spare CRTs turn up. Unfortunately, after playing about 10 minutes something snapped inside and the screen went dark although the sound was still OK. I checked in back and the damper was red plating

Eventually I'll get around to pulling it apart, just to satisfy my curiosity if nothing else, but for now it's back to other projects.

bandersen · #74 08-26-2016, 11:56 AM

I was poking around on ebay and stumbled across the Sams for the Airline version.

http://www.ebay.com/itm/1957-AIRLINE...MAAOSw9mFWL~4F

It's a GRX-4030A which lead me to finding it on tvhsitory.tv.

I still haven't gotten around to fixing mine, but at least now I know what the knobs look like. I wouldn't mind finding the Airline version too.

dieseljeep · #75 08-28-2016, 07:24 PM

Quote:

Originally Posted by bandersen

I was poking around on ebay and stumbled across the Sams for the Airline version.

http://www.ebay.com/itm/1957-AIRLINE...MAAOSw9mFWL~4F

It's a GRX-4030A which lead me to finding it on tvhsitory.tv.

I still haven't gotten around to fixing mine, but at least now I know what the knobs look like. I wouldn't mind finding the Airline version too.

I always found it interesting that some of the simplest TV's, radios and phonos get a lot of entries on this forum, which is great with me. I had to reread the entire thread, as it's been a while.