kvflyer
07-05-2010, 08:46 AM
Well, I got this set in about 2008. Somewhere, a gentleman that collects televisions found out that I was looking for a replacement of the first TV I had as a teenager. It was an Admiral 26R12. Big brown Bakelite cabinet with an odd square corner 16" CRT. We agreed on a price and I bought it, and picked it up from his home. It was reported to be working and unrestored. I didn't try it because all of the parts were there. Now I know that there are many differing opinions about what to pay for an item, what it is worth etc. Some will not touch a TV unless the CRT is in good condition, not to mention the knobs, flyback, yoke and power transformer. I am of the opinion that cosmetics are first followed by completeness.
So, this guy sat for about a year and one day I thought since it was "working", let me give it a try. No, I did not use my variac since it was downstairs. I kept my hand on the power cord. It worked! So, this would be an excellent candidate for restoration because I had a very good starting point.
The TV:
http://www.streitsonline.com/don/26R12_1.jpg
You will notice that the volume knob is from a different color set since it is a mahogany color instead of the brown that matches Bakelite. It is an original knob, not an aftermarket replacement. I have been assured by other "Admiral Experts" that they did use that color as well.
The chassis before restoration:
http://www.streitsonline.com/don/26R12_Before.jpg
As you can see, it is very unmolested. One of the power supply filter capacitors must have been bad in the past because you will see the large yellow cap mounted below the chassis. I started at one corner of the chassis and worked my way across to the other side. All filter capacitors were removed, pried open and new individual capacitors mounted inside of the cans to preserve the original appearance. I can usually do a cap in an hour. It takes that long to mount terminal strips and move wires below so that is my preferred method. In one situation, I had all of the correct values but they would not fit inside of the can. I think it was 20µFD @ 450VDC. But two 10µFD caps would fit so that is what I did. What luck!
http://www.streitsonline.com/don/26R12_after.jpg
It did work after the new caps were installed. Resistors were checked and several were high so they too were replaced. Random checking of mica caps found them to all be good as new. So they were left in place.
http://www.streitsonline.com/don/before.jpg
The picture above was how it looked with the original CRT. The CRT had a booster on it so I put in a NOS RCA 16TP4 that I had. Initially, it worked well for about 2 hours. Then I heard a pop, not unlike the sound of discharging an electrolytic cap with a screwdriver!
Now it looked like this!
http://www.streitsonline.com/don/after.jpg
I fooled with it for a while. Voltages looked good except for the plate of V401A. Should be 100V and it was 175V. The brightness control did not affect the reading (Major Hint there ;)) I tried substituting another vertical oscillator transformer and output transformer from a donor chassis that I have. No dice.
http://www.streitsonline.com/don/VertVolt.jpg
Well, other things came up, I was tired of fooling with it and put it back into the case. That was April 2009!
I was reading another thread by wa2wise about his 24R12; essentially the same set with a 14" CRT. He mentioned a bad cathode bypass electrolytic capacitor on the 6S4 Vertical Output tube. I put the chassis back on the bench and tried that first. Not to be! But remember now, it is about 15 months later and I have a clear mind (If you can believe that!). Since I knew that I had substituted parts, not just tested them, I started fresh.
The key here is the voltage not being varied by the height control. I pulled the control and unsoldered the wire to the end lug, not the wiper lug. Measuring the control, I got erratic readings at first. (Elapsed time, maybe 45 minutes now) Then, it settled down and started reading close. It is a 2.5MΩ pot and it read about 3MΩ. Yes, too high but remember, it is used as a variable resistor, not a pot; one side is open.
Put it back into the chassis and now, it works! I could not believe it but one of the members on ARF suggested tin whiskers on the pot, possibly shorting it out. Now I know that there really are such things as tin whiskers. NASA had problems with them in their satellites years ago. So, most likely, I must have wiped them away and the control now works.
So far, the TV has been on for 2 hours and then 5 hours. I am using a Blonder Tongue BAVM-Z agile modulator, set to CH 7 and broadcasting within the home. It just works!
More to come when I have more time...
So, this guy sat for about a year and one day I thought since it was "working", let me give it a try. No, I did not use my variac since it was downstairs. I kept my hand on the power cord. It worked! So, this would be an excellent candidate for restoration because I had a very good starting point.
The TV:
http://www.streitsonline.com/don/26R12_1.jpg
You will notice that the volume knob is from a different color set since it is a mahogany color instead of the brown that matches Bakelite. It is an original knob, not an aftermarket replacement. I have been assured by other "Admiral Experts" that they did use that color as well.
The chassis before restoration:
http://www.streitsonline.com/don/26R12_Before.jpg
As you can see, it is very unmolested. One of the power supply filter capacitors must have been bad in the past because you will see the large yellow cap mounted below the chassis. I started at one corner of the chassis and worked my way across to the other side. All filter capacitors were removed, pried open and new individual capacitors mounted inside of the cans to preserve the original appearance. I can usually do a cap in an hour. It takes that long to mount terminal strips and move wires below so that is my preferred method. In one situation, I had all of the correct values but they would not fit inside of the can. I think it was 20µFD @ 450VDC. But two 10µFD caps would fit so that is what I did. What luck!
http://www.streitsonline.com/don/26R12_after.jpg
It did work after the new caps were installed. Resistors were checked and several were high so they too were replaced. Random checking of mica caps found them to all be good as new. So they were left in place.
http://www.streitsonline.com/don/before.jpg
The picture above was how it looked with the original CRT. The CRT had a booster on it so I put in a NOS RCA 16TP4 that I had. Initially, it worked well for about 2 hours. Then I heard a pop, not unlike the sound of discharging an electrolytic cap with a screwdriver!
Now it looked like this!
http://www.streitsonline.com/don/after.jpg
I fooled with it for a while. Voltages looked good except for the plate of V401A. Should be 100V and it was 175V. The brightness control did not affect the reading (Major Hint there ;)) I tried substituting another vertical oscillator transformer and output transformer from a donor chassis that I have. No dice.
http://www.streitsonline.com/don/VertVolt.jpg
Well, other things came up, I was tired of fooling with it and put it back into the case. That was April 2009!
I was reading another thread by wa2wise about his 24R12; essentially the same set with a 14" CRT. He mentioned a bad cathode bypass electrolytic capacitor on the 6S4 Vertical Output tube. I put the chassis back on the bench and tried that first. Not to be! But remember now, it is about 15 months later and I have a clear mind (If you can believe that!). Since I knew that I had substituted parts, not just tested them, I started fresh.
The key here is the voltage not being varied by the height control. I pulled the control and unsoldered the wire to the end lug, not the wiper lug. Measuring the control, I got erratic readings at first. (Elapsed time, maybe 45 minutes now) Then, it settled down and started reading close. It is a 2.5MΩ pot and it read about 3MΩ. Yes, too high but remember, it is used as a variable resistor, not a pot; one side is open.
Put it back into the chassis and now, it works! I could not believe it but one of the members on ARF suggested tin whiskers on the pot, possibly shorting it out. Now I know that there really are such things as tin whiskers. NASA had problems with them in their satellites years ago. So, most likely, I must have wiped them away and the control now works.
So far, the TV has been on for 2 hours and then 5 hours. I am using a Blonder Tongue BAVM-Z agile modulator, set to CH 7 and broadcasting within the home. It just works!
More to come when I have more time...