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 Post subject: Admiral 19A11S & Faudell & White's brilliant circuit.
PostPosted: Jan Fri 17, 2020 12:49 am 
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Posts: 482
This circuit may be of interest, as it is found in the 19A11S and some Motorola sets using the 7JP4 crt.

It is quite a story, I came across it many years ago in the Admiral 19A11S set that had the horizontal transformers missing, so I redesigned the transformers, but to do that I had to figure out how it worked, there is nothing about this circuit in the standard USA textbooks such as Grob & Fink.

It turned out, after searching for 40 years or more, I found it was designed by Faudell & White.

It is a very clever idea, to chop up a sinewave resonant circuit (with voltage magnification) to produce a very high voltage linear sawtooth wave for electrostatic horizontal deflection, so from a mere 250V DC supply, one triode & two transformers you can acquire two 450V pp linear anti-phase sawtooth waves for horizontal scanning.

One of the arguments favoring magnetic deflection over electrostatic was that as the CRT's got bigger (and the required EHT increased) the high voltage deflection demands increased and linear amplifiers, to get the required deflection voltage ,would have to run off very high HT voltages. In electrostatic deflection the amount of deflection is inversely proportional to the EHT voltage. In magnetic deflection the amount of deflection is inversely proportional to the square root of the EHT voltage (all other things equal).

Anyway, I was so impressed by Faudell & White's solution I wrote an article about it. It is interesting that this configuration never appeared in any British TV I know of.

http://worldphaco.com/uploads/Admiral_TV..pdf


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 Post subject: Re: Admiral 19A11S & Faudell & White's brilliant circuit.
PostPosted: Jan Fri 17, 2020 2:07 am 
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I remember reading this, and was similarly blown away by the cleverness of it.

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A collector of TV signal boosters and UHF converters -- God help me!
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 Post subject: Re: Admiral 19A11S & Faudell & White's brilliant circuit.
PostPosted: Jan Fri 17, 2020 9:46 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Crystal Bay, NV
Wow! You are to be congratulated for your knowledge, craftsmanship and artistry. I look forward to any other projects you may be interested in.
=======
Ron


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 Post subject: Re: Admiral 19A11S & Faudell & White's brilliant circuit.
PostPosted: Jan Sat 18, 2020 11:45 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Phoenix, Arizona
Very Interesting!

I have one of those sets and it works quite well. I paid little attention to the H-sweep circuit.

When I got the set it it was missing the knobs, the mounting plate for the tuner, had a big crack in the Bakelite cabinet.

It is now restored, complete and working from a trashed set for parts.

The biggest problem is the plastic window over the CRT is warped and hard to see through. I have a better one I salvaged form the junk set but I have fear factor trying to remove those clips without breaking the Bakelite.

I have a NOS 7JP4 installed.

I will say the picture quality is much better on an RCA 621TS which uses electromagnetic deflection but electrostatic focus.

Jim


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 Post subject: Re: Admiral 19A11S & Faudell & White's brilliant circuit.
PostPosted: Jan Sun 19, 2020 12:38 am 
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jimmc wrote:
Very Interesting!

I have a NOS 7JP4 installed.

I will say the picture quality is much better on an RCA 621TS which uses electromagnetic deflection but electrostatic focus.

Jim


Where did you find the NOS 7JP4 ?

My experience has been that the focus in an electromagnetically focused CRT maintains a better and more stable state with changes in beam current, than an electrostatic focused tube, especially with the earlier design CRT guns. I was less concerned about the deflection method affecting the focus, but its a good point.

I had the opportunity to compare 3 TV sets, all 1939 and 5" diameter CRT's:

The Andrea KTE-5 (uses a 5AP4 CRT, which was a shortened 5BP4 designed for Andrea by National Union)
The Meissner 5" TV Kitset (uses a 5BP4)
The HMV 904, Uses an Emiscope 3/1, but I did not have one so I fitted RCA's 5FP4 (designed by RCA for the TK-30 camera viewfinder). Magnetic focus.

All running of a similar EHT voltage around 2400V

The 5FP4 has substantially better focus that is stable with changes in beam current (contrast and brightness) compared with the two other electrostatic focused CRT's.

It might depend on the gun design with electrostatic focus, I agree the 7DP4 in the 621TS (I have one of these too) does maintain a good focus over a range of beam currents, so it might just be that the guns in the other electrostatic focused CRT's were not as well designed. Though the gun structure in the 7JP4 is fairly elaborate.


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 Post subject: Re: Admiral 19A11S & Faudell & White's brilliant circuit.
PostPosted: Jan Mon 20, 2020 3:09 am 
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Another possible difference in the comparison of the 5KP4 to the 5BP4 and similar types, is that the 5KP4 was likely designed by RCA specifically for TV monitor service. As such, it didn't have the cost constraints of mass produced home TV CRTs, so gun structure, phosphor makeup and production care could be optimized for picture quality.

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 Post subject: Re: Admiral 19A11S & Faudell & White's brilliant circuit.
PostPosted: Jan Mon 20, 2020 3:03 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1687
Location: Phoenix, Arizona
Back in my younger years I acquired a NOS 7JP4 which I had moved around several sets ending up in the Admiral 19A11 It never got use other than an occasional test.

I hardly ever turn on the Admiral because of the wavy plexiglass. Without it the picture is fine.

I tried to find the SAM's for the Admiral just to study the sweep circuit, I'm guessing I have the Riders somewhere.

Maybe I will try to remove the Plexi now that I am motivated and try not to destroy the cabinet.

Jim


Last edited by jimmc on Jan Mon 20, 2020 9:24 pm, edited 1 time in total.

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 Post subject: Re: Admiral 19A11S & Faudell & White's brilliant circuit.
PostPosted: Jan Mon 20, 2020 4:23 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1687
Location: Phoenix, Arizona
The article on the Flyback sweep circuit in this TV is extremely amazing. One more winding on the transformer and you would have High Voltage.

Here is a pic of my Admiral 19A11S viewing the trusty B&K Analyzer.

As seen, the resolution is hampered by the foggy, wavy plastic window over the CRT.

I did dig out the service details in Riders Vol 3.

The good features of the set are; Power Transformer, Turret tuner. stable High Voltage. Ratio Detector for FM audio, and Intercarrier audio

This second pic is the actual transformer (T-4) that does the H-sweep.

The safety glass pictured is better than the glass (plastic) in the set and the four clips are what keep it in place.

I bought a box of Admiral parts on ebay to get the mounting plate for the tuner. included was a tuner and all the transformers and coils that were parted out of one of these sets. I also got a bakelite cabinet that was better than mine. I salvaged the plastic window and managed to bust off all of the studs these clips slide over. They are extremely brittle. As that cabinet had a big crack in the top I sent it to the after life.

The salvaged window is still quite wavy and distorted but clearer, but still foggy. It is in the plastic and I have tried to polish it out but it is not surface.

Jim


Attachments:
Admiral 19A11S.jpg
Admiral 19A11S.jpg [ 144.31 KiB | Viewed 1946 times ]
Adm-1.jpg
Adm-1.jpg [ 155.42 KiB | Viewed 1926 times ]
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 Post subject: Re: Admiral 19A11S & Faudell & White's brilliant circuit.
PostPosted: Jan Fri 24, 2020 3:14 pm 
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Joined: Jan Mon 28, 2013 9:35 pm
Posts: 1600
Location: Santa Rosa, CA
Nice write up, thanks! My TV collection consists mostly of electrostatic
sets and I've had to troubleshoot this section many times so had
an idea of how it worked but your presentation fills in a few blanks.
Steve

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 Post subject: Re: Admiral 19A11S & Faudell & White's brilliant circuit.
PostPosted: Jan Fri 24, 2020 5:11 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1687
Location: Phoenix, Arizona
I don't get credit for the wrightup but I agree it is very good information.

I had generally assumed all sets used about the same sweep design which used a 6SN7 or 6SL7 amplifier with the plate voltaged derived from the High voltage supply bleeder circuit.

I reduced my TV collection down to four 7" sets one 3" set and one 21" Predicta. After reading the wrightup I dug the Admiral out from under my desk and turned it on and fed the B&K analyzer in and marveled at how linear the picture is.

Most sets that use the standard circuit are quirkey about capacitor values and the accuracy of the phase inverter.

As I understand the circuit, The triode is turned on for about 9 microseconds which is most of the Horizontal Blanking interval. The tube then is turned off by the blocking osci;llator feature and Trace is then at the mercy of the T-2 inductance for the 63 microsecond active video interval.

One tube, a couple of transformers, and a handfull of cheap parts. No drain on the high voltage supply (until the HV caapacitors get leaky).

I have a small box of parts which include a tuner all of the centering pots, all of the IF coils, which I will be happy to share.

I have a better safety glass (plastic) window and I may get brave enough to try and replace it.

Jim


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 Post subject: Re: Admiral 19A11S & Faudell & White's brilliant circuit.
PostPosted: Jan Sat 25, 2020 10:37 pm 
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Joined: Jan Thu 16, 2020 12:29 am
Posts: 482
The cloudy plexiglass can be improved significantly on the 19A11S by using the three grades of Novus plastic polish sold by Antique Electronics supply. If its surface bad, crazed and very marked, it might require 2000 grade paper prior to the first coarse grade of the polish.

On mine though, even when the surface was restored to a high gloss, the thickness of the material is suffering from some clouding. It is not noticeable over the area where the gold paint is. My ultimate plan is to CNC route the central area out and replace it with a replica clear instert. When that is done I will publish the article on in it.

I did a similar thing with the cloudy knob on this radio:

viewtopic.php?f=4&t=370796


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 Post subject: Re: Admiral 19A11S & Faudell & White's brilliant circuit.
PostPosted: Jan Sat 25, 2020 11:51 pm 
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Joined: Jun Mon 24, 2013 3:00 pm
Posts: 1453
Location: Champaign IL 61822
If you are worried about damaging the posts that those clips push on, then
what you need to do is gather up some patience and actually file through the metal on both sides so they fall off.

Why not make a new Plexiglass plate?


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 Post subject: Re: Admiral 19A11S & Faudell & White's brilliant circuit.
PostPosted: Jan Sun 26, 2020 12:42 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1687
Location: Phoenix, Arizona
I tried a couple of tricks to get the clips off to no avail. I am going to try grinding through with a Dremel tool.

I have a much better window and the four clips from the broken cabinet I discarded. This window has weird stress lines in the plastic and has some deep scratches in the front. It takes about 10 db of light. This set looks plenty good without the cabinet.

There is also a thin foam rubber surround which is plenty soft and can be saved.

I tried polishing it out with some Met-All polish and finished with Meguires 20. I may try 2000 grit sand paper and finish with my chemicals (above). After Dremel time.

As I looked through the SAM's for other Electrostatic sets I see versions of this H-sweep circuit. Motorola VT-73 is close.

Anyway time to fix this old girl (or boy).

Making a new window could be challenging, it is a molded item with a large flange. Maybe a 3D printer.

Jim


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 Post subject: Re: Admiral 19A11S & Faudell & White's brilliant circuit.
PostPosted: Jan Sun 26, 2020 9:54 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1687
Location: Phoenix, Arizona
I succeeded in re-windowing my Admiral 19A11S TV set.

It was a challenge but the new window is in and is nice and clear.

The Story:

I used a Dremel tool to cut the corner off each of the four clips that keep the window and a foam rubber mask in place in the deep front panel of a Bakelite cabinet

I salvaged the new plastic window from the original cabinet that came with the set which had a serious crack in the top. When I tried to remove it without further destroying the cracked cabinet I found the four studs cast into the Bakelite snapped off easily and can't be glued back

My set is now made up of parts from at least four other TV's; Knobs from a Knob dealer, Tuner parts and mounting, Cabinet and back and safety glass from my original cabinet.

The new glass is slightly foggy but the set is very watchable. The foam rubber mask is in one piece and survived. I did not put the four clips back so far but I may later. The CRT keeps the window in place.

I recapped most of the set, resistors are original. Most of the tubes say Admiral. I did replace the Contrast pot using a better one from the junk parts I bought on ebay to get the tuner plate.

The Horizontal linearity and available width is quite flawless. The Vertical is slight egg shaped and this set has a vertical Linearity pot on the far left back where I expected brightness to be.

Jim


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 Post subject: Re: Admiral 19A11S & Faudell & White's brilliant circuit.
PostPosted: Feb Sat 01, 2020 3:31 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1687
Location: Phoenix, Arizona
I was inspired by the Hugo Holden article to dig out my little Bakelite Admiral 19A11S.

In the post above I wanted to replace the safety glass window for which I had a spare I had removed from a destructed Bakelite cabinet.

I did succeed in removing the push-on clips that kept the glass (Plastic) in the cabinet. There is a foam surround that is fragile but still intact which I was able to recover in one piece as well.

The Bakelite Cabinet is molded in one piece, the clear window fits through the front of the cabinet and is kept in place by the four clips.

In this picture the view of the screen is clear (except for glare of overhead lights).

I haven't put the clips back yet as the CRT keeps the window and foam piece nicely in place.

It requires surgical skills to get in with a Dremel tool with a cutting disk and saw through the spring-steel clips and then unstuck them from the four fragile posts formed in the Bakelite cabinet. The clips were stuck in the foam rubber surround which is becoming petrified.

In this set the foam rubber is not as important as some set as the CRT is secured to the chassis, and the rubber is fairly thin.

Hugo Holden is known for his highly elaborate TV restorations and detailed circuit analysis. My favorite is for the RCA 621TS.

My set also has a vertical linearity control which is not in the Riders version. I would like to find a schematic that shows that.

I did not originate this thread, but thanks!

Jim


Attachments:
Ad 19A1-3.jpg
Ad 19A1-3.jpg [ 135.97 KiB | Viewed 1608 times ]
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 Post subject: Re: Admiral 19A11S & Faudell & White's brilliant circuit.
PostPosted: Feb Tue 04, 2020 4:53 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1687
Location: Phoenix, Arizona
After replacing the plastic safety window, I have had the set in the morning news watching position for the past few days.

I felt the picture was a little dimmer than it should be. I was reading through the detailed service notes in Riders 3 and there is a paragraph of production changes.

They say that some power transformers were manufactured to be used with a 5U4 and not a 5Y3. This is noted by a red dot on top of the transformer. My transformer has an orangish-red mark on top so I poped in a 5U4 and the tv picture now looks as good as that color photo in the ad at the satart of ths thread. My chassis is stamped 5Y3.

A 5U4 has a 3 Amp filiment and a 5Y3 has a 2 Amp filiment. The service notes say the B+ will be 30 volts low with the 5Y3 instead of the 5U4. There is also a resistance measurement however I have a spare transformer with a dot, it actually measures lower the the service notes say. I checked the temperature of the transformer and it hit about 118 F after a couple of hours.

While watching Impeachment for a couple of hours yesterday, the contrast started jumping around like an AGC problem. It finally failed dim. I found the 6AG5 in the tuner to be failed so I pulled the chassis and replaced it and I'm back to perfection. I substituted tubes as I had previously replaced all the paper capacitors in the set.

I have a some spare parts which include a power transformer so I'm not worried about 5U4 overload, I plan to pull the chassis and I will measure voltages and transformer resistance. The power supply is very straight forward, 250 volts of B+, a filter choke and a couple of electrolytics. There is a 130 volt B supply derived from the cathode of the Audio output tube.The 130 volts is actually regulated by the audio out tube, this powers the tuner and IF amp.

The horizontal sweep circuit (The original intent of this thread) is very linear and has plenty of headroom for width. When I last worked on this TV about 7 years ago, I hand selected the 1B3 and 6V6 to get as much EHT as the circuit could deliver. Didn't ever try a 5U4.

Verticle sweep works fine noting the V output 6SL7 gets its plate voltage from the EHT supply. My set has a linearity pot to the left of the brightness pot. I have not found a schematic showing this.

Jim


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 Post subject: Re: Admiral 19A11S & Faudell & White's brilliant circuit.
PostPosted: Feb Sat 08, 2020 11:11 pm 
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Location: Warren, Ohio, USA
jimmc wrote:
I was inspired by the Hugo Holden article to dig out my little Bakelite Admiral 19A11S.


My set also has a vertical linearity control which is not in the Riders version. I would like to find a schematic that shows that.

I did not originate this thread, but thanks!

Jim


Attachment:
AdmiralTelevisionChassis19A1Schematic.pdf [607.9 KiB]
Downloaded 48 times


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 Post subject: Re: Admiral 19A11S & Faudell & White's brilliant circuit.
PostPosted: Feb Mon 10, 2020 4:34 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Phoenix, Arizona
This link produced a schematic with the Vertical Linearity control.

Thanks!


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 Post subject: Re: Admiral 19A11S & Faudell & White's brilliant circuit.
PostPosted: Feb Tue 11, 2020 2:41 pm 
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Location: Warren, Ohio, USA
jimmc wrote:
This link produced a schematic with the Vertical Linearity control.

Thanks!


You’re welcome! Now, if only I could figure out why the picture in my set isn’t tall enough.

Steve Chambers


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 Post subject: Re: Admiral 19A11S & Faudell & White's brilliant circuit.
PostPosted: Feb Tue 11, 2020 4:53 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1687
Location: Phoenix, Arizona
My set has the Vertical Lin control which happens to be the left most pot (from back) which tripped me up as I was trying to adjust brightness.

Since the vertical output derives its plate voltage from the high voltage supply I would check or just replace those high value resistors in what they call the bleeder string.

Another problem I have had is the capacitors that couple the sweep to the CRT need to be the proper value (.005 mfd vertical) and not old and leaky. I have ceramic capacitors in my set for the horizontal side (.001 mfd), but people have had trouble getting ceramic to work and I go for the ASC high voltage cap's which are available. The ceramics seem to have trouble with lower frequency signals.

I have also had trouble getting good sweep and linearity from the verticle circuit getting good capacitors in the phase inverter part of that Balanced amplifier circuit Usually the mica cap is OK.

When I got my set about 10 years ago I replaced most of the paper capacitors and I had it working. It seemed a little dim and I hand picked the 6V6 and the 1B3 to get the best high voltage. I have always had plenty of Height and Width on this set. While reading through the service notes they point out that some power transformers were made to use the 5U4 rectifier and not a 5Y3. I put in a 5U4 and everything looks much better. I should still check the voltages and measure the transformer winding resistance.

High voltage can affect height and width but since the vertical plate voltage is obtained directly from the high voltage it could have an effect if something has changed value.

I can overscan by at least an inch and a half both vertivcal and horizontal now and with the 5Y3 in.

The beauty of the horizontal circuit is it works very good from the 250 volt B+, and doesn't need plate voltage from the HV supply.

I have been watching morning news on my set for the past couple of weeks and the set is running stable. The bigest improvement was replacing the plastic safety glass window (which I just happen to have).

I need to clean up the electrolytic capacitors which are scabbed in used tubuler type from my junk box. Then I will have to find something to tinker with.

Jim


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