I was a kid when these sets were new. It was my job to ride theV and H controls as they drifted. I was totally amazed the first time I saw the TV repair man use his Weller Soldering gun. I have worn out many Weller 140 / 180 guns.
OMG Bob...you and I are following very similar restoration paths! That looks like the exact chassis in my 805! I just finished replacing the yoke on mine to get rid of the trapezoidal picture issue I had and I posted a pic on VK of the successful swap. I think you will find the controls on this TV are a mess and a bear to work on in the compact chassis. I had a bad brightness control and a bad volume control, both of which, unfortunately, were a section of dual potentiometers with concentric shafts. A parts chassis was a must for my restoration. Those boards on the 805 are 3 rails of a floating, B- ground network.
Boy that is really a TIGHT little set! Definitely one of the rougher ones I've watched you do. Makes my 1401 look easy. LOL. Great picture tube anyway, once you get the new coating on it. Really nasty, but once you get it cleaned up, it will start coming together. I'll be watching this one with great interest.
Sometimes you just need to throw things away into the Wild Blue Yonder!!!! So many other Vintage TV sets that are very cool, Art Deco, and worth the time, $$$$ and effort...
Over the years I worked on and restored all kinds of TV sets,VCR’s , Radios and color TV’s. Here in my September years I have settled in on the 1950’s RCA Automatic 45 record changer models. My wife says a cluttered desk shows a brilliant mind. She should see our bench’s , but won’t even come in my shop.
If you want to get mildew off those parts try turning a can of canned air upside down and spraying the parts. Works like dry ice so it should also evaporate quickly. May take a couple of cans if it is thick however. White vinegar on the pot covers should be used first before trying anything else. It won't harm any surrounding parts but it will smell like hell. Steve
Hi Bob, Great information, as always. Just a quick production note: over the past few or so videos, it appears that you are using an auto focus feature that keys on movement. The camera will focus on your hands when you are pointing from some distance closer to the camera which renders the subject set out of focus. It stays out of focus until your hands are closer to the set or until the auto focus times out and reacquires the distance. Do you use a monitor off camera so you can reference the shot continuously without turning around? I am assuming your camera can work that way but it is a more complex setup.
After World War Two, General Electric went into the hyper cost cutting mode with all of their consumer electronics. Given that fact, at first I was surprised to see the use of selenium rectifiers, as they cost more than a rectifier tube at that time. Then, I thought about the reasons why. You would need 2 rectifier tubes with a plate current of at least one amp with an indirectly heated cathode. Since the heater to cathode voltage limit is typically 200 volts, this circuit would need a heater to cathode rating of at least 500 volts, which means an isolation transformer would be needed to power the filament. (I guess some of the later damper tubes could meet this spec) With the costs piling up using a vacuum tube rectifier, the selenium rectifier became the obvious choice.
Emerson used 5x 25Z6 in their earlier hot-chassis sets. I had heard that selenium rectifiers were actually cheaper than tube rectifiers but less reliable. I don't know if this is true or not.
@@eDoc2020 I don't know the actual cost differences between the selenium versus a vacuum tube rectifier. I started TV repairing in 1971 and when a selenium rectifier would fail, they were considered obsolete and always replaced by a "Top Hat" silicon rectifier. The 5U4 was the default standard rectifier tube when the set had a power transformer. Each selenium rectifier plate had a forward voltage drop similar to a silicon diode. The reverse voltage rating was about 25 volts per plate and they had a lot of leakage, which would get worse over time. It was common for selenium rectifiers to fail, making that unmistakable toxic smell. The 25Z6 had a maximum heater to cathode rating of 350 volts so, not really a good candidate for a series string filament hot chassis voltage doubler since the peak voltage available with that type of circuit is 535 volts. Rectifier tubes are very sensitive to surge currents thus, typically have about 30uF cap size limit when the cap is connected directly to the cathode. TVs naturally have a relatively high B+ current demand and need at least 100uF on the rectifier output for ripple filtering. In such cases, a resistor needs to be added in series with each rectifier plate to limit surge currents.
Off topic question. If I have a center tap output transformer that is measuring 16k plate to plate reflected impedance. Is each tube seeing 8k of that? I've seen evidence suggesting that each plate will actually see half that much. 4k per side? I'm trying to plot load lines but this confuses me
There are various googleable audio DIY pages discussing the math and the plotting for this, including whether you want to run as class A or class AB. Wishing you success on your project.
I didn't notice any JAN (joint Army-Navy) war-surplus parts in this early postwar set. Perhaps by the time this television came off of the assembly line the mountain of wartime electronic parts had evaporated.
I'd consider this a late post war set. From 1949/50. The 800A is the early one. Even so, I'm not sure I've seen surplus parts in any TVs. Maybe the low-end brands used them but the big guys (RCA, GE, Zenith etc) used new parts from well known makers.
I see Westinghouse, Sylvania and RCA tubes that look very old. With the replacement capacitors and the replacement CRT this set must have seen quite a lot of use in its day. Hopefully it's not as butchered as the last one.
I was a kid when these sets were new. It was my job to ride theV and H controls as they drifted. I was totally amazed the first time I saw the TV repair man use his Weller Soldering gun. I have worn out many Weller 140 / 180 guns.
Wow. Working on a TV chassis like that could leave a guy scarred for life.
Perfect timing Bob! I have 2 of these which I need to restore! 👍🏻
Yes I have one too. Really looking forward to this.
OMG Bob...you and I are following very similar restoration paths! That looks like the exact chassis in my 805! I just finished replacing the yoke on mine to get rid of the trapezoidal picture issue I had and I posted a pic on VK of the successful swap. I think you will find the controls on this TV are a mess and a bear to work on in the compact chassis. I had a bad brightness control and a bad volume control, both of which, unfortunately, were a section of dual potentiometers with concentric shafts. A parts chassis was a must for my restoration. Those boards on the 805 are 3 rails of a floating, B- ground network.
Boy that is really a TIGHT little set! Definitely one of the rougher ones I've watched you do. Makes my 1401 look easy. LOL. Great picture tube anyway, once you get the new coating on it. Really nasty, but once you get it cleaned up, it will start coming together. I'll be watching this one with great interest.
The compactness reminds me of the Ekco TMB272 9 inch set
Sometimes you just need to throw things away into the Wild Blue Yonder!!!! So many other Vintage TV sets that are very cool, Art Deco, and worth the time, $$$$ and effort...
Golly Lee Sgt Carter, looks all da parts!
The brace on the backside of the crt is normal. I have a set like it, and it is in the same position.
Over the years I worked on and restored all kinds of TV sets,VCR’s , Radios and color TV’s. Here in my September years I have settled in on the 1950’s RCA Automatic 45 record changer models. My wife says a cluttered desk shows a brilliant mind. She should see our bench’s , but won’t even come in my shop.
Bob this was so exciting to watch and really anxious to see the next video Wow what a great treat this Sunday.
I think you'll enjoy the next installment even more. Making good progress :)
If you want to get mildew off those parts try turning a can of canned air upside down and spraying the parts. Works like
dry ice so it should also evaporate quickly. May take a couple of cans if it is thick however. White vinegar on the pot covers
should be used first before trying anything else. It won't harm any surrounding parts but it will smell like hell. Steve
Hi Bob, Great information, as always. Just a quick production note: over the past few or so videos, it appears that you are using an auto focus feature that keys on movement. The camera will focus on your hands when you are pointing from some distance closer to the camera which renders the subject set out of focus. It stays out of focus until your hands are closer to the set or until the auto focus times out and reacquires the distance. Do you use a monitor off camera so you can reference the shot continuously without turning around? I am assuming your camera can work that way but it is a more complex setup.
I switch to manual focus tonight so we'll see how it goes in future videos. Thanks for the feedback.
After World War Two, General Electric went into the hyper cost cutting mode with all of their consumer electronics. Given that fact, at first I was surprised to see the use of selenium rectifiers, as they cost more than a rectifier tube at that time. Then, I thought about the reasons why. You would need 2 rectifier tubes with a plate current of at least one amp with an indirectly heated cathode. Since the heater to cathode voltage limit is typically 200 volts, this circuit would need a heater to cathode rating of at least 500 volts, which means an isolation transformer would be needed to power the filament. (I guess some of the later damper tubes could meet this spec) With the costs piling up using a vacuum tube rectifier, the selenium rectifier became the obvious choice.
Emerson used 5x 25Z6 in their earlier hot-chassis sets. I had heard that selenium rectifiers were actually cheaper than tube rectifiers but less reliable. I don't know if this is true or not.
@@eDoc2020 I don't know the actual cost differences between the selenium versus a vacuum tube rectifier. I started TV repairing in 1971 and when a selenium rectifier would fail, they were considered obsolete and always replaced by a "Top Hat" silicon rectifier. The 5U4 was the default standard rectifier tube when the set had a power transformer.
Each selenium rectifier plate had a forward voltage drop similar to a silicon diode. The reverse voltage rating was about 25 volts per plate and they had a lot of leakage, which would get worse over time. It was common for selenium rectifiers to fail, making that unmistakable toxic smell.
The 25Z6 had a maximum heater to cathode rating of 350 volts so, not really a good candidate for a series string filament hot chassis voltage doubler since the peak voltage available with that type of circuit is 535 volts.
Rectifier tubes are very sensitive to surge currents thus, typically have about 30uF cap size limit when the cap is connected directly to the cathode. TVs naturally have a relatively high B+ current demand and need at least 100uF on the rectifier output for ripple filtering. In such cases, a resistor needs to be added in series with each rectifier plate to limit surge currents.
Off topic question. If I have a center tap output transformer that is measuring 16k plate to plate reflected impedance. Is each tube seeing 8k of that? I've seen evidence suggesting that each plate will actually see half that much. 4k per side? I'm trying to plot load lines but this confuses me
There are various googleable audio DIY pages discussing the math and the plotting for this, including whether you want to run as class A or class AB. Wishing you success on your project.
Does the flaked off DAG need to be replaced in some way? Is there a spray on coating that would be equivalent?
Yes and yes. Spray on graphite products work well like 'slip-plate'.
I didn't notice any JAN (joint Army-Navy) war-surplus parts in this early postwar set. Perhaps by the time this television came off of the assembly line the mountain of wartime electronic parts had evaporated.
...that's hard to say...
I'd consider this a late post war set. From 1949/50. The 800A is the early one. Even so, I'm not sure I've seen surplus parts in any TVs. Maybe the low-end brands used them but the big guys (RCA, GE, Zenith etc) used new parts from well known makers.
I see Westinghouse, Sylvania and RCA tubes that look very old. With the replacement capacitors and the replacement CRT this set must have seen quite a lot of use in its day. Hopefully it's not as butchered as the last one.
Yes, I'm sure it did. I think only one original tube is left. Some caps have been replaced and the circuit breaker bypassed
I remember that series you did, although it was a great, you really burned yourself out and you did radios for a while after
I will admit, I would NOT want to work on that set! Good grief!