View Full Version : Motorola 16VF8


EdKozk2
05-26-2017, 08:35 PM
My son spotted this on CL last night. We picked it up this afternoon near Fox Lake, IL. It uses the TS-16A chassis and a 16AP4. Sams' folder 93-7.

EdKozk2
05-26-2017, 08:44 PM
More pictures. The cabinet is wider and taller than my Dumont RA-109 A3 Sherbrooke, but not as heavy.

EdKozk2
05-27-2017, 02:39 PM
These are the pictures the CL lister emailed me of this set before I picked it up. They were taken before the set was put in storage for awhile. The left upper door hinge and cabinet hadn't been damaged yet. Last picture is from an old 1949 Motorola advertisement.

bandersen
05-27-2017, 03:42 PM
Great find! I like the color and design a lot. The chassis reminds me of the 19K1 I work on a few years ago: http://www.videokarma.org/showthread.php?t=248133

Tim
05-27-2017, 03:45 PM
I imagine not many of these survive. Motorola also had a 19" version of the set. Model 19F1 the "Gainsborough". Same cabinet style but possibly even larger.

Eric H
05-27-2017, 05:28 PM
The date code stamped on the base of the CRT means it was probably replaced at some point, hopefully still good.

Electronic M
05-28-2017, 01:04 AM
Nice score, Ed!

That is one of the classier looking 50's combos.

EdKozk2
05-28-2017, 11:02 AM
The date code stamped on the base of the CRT means it was probably replaced at some point, hopefully still good.
I hope the CRT is OK also. The craigslist ad stated " everything works". The HS-211 AM/FM/phono chassis has it's own power transformer with a 6V6 P-P output.

EdKozk2
05-28-2017, 11:33 PM
Took a chance after testing the power transformer AC voltages today. I slowly powered up the set with the two 5U4 rectifiers and a new 1/4 amp fuse in the horizontal circuit. I got a fairly bright horizontal line across the screen. At least I now know the CRT is usable. The vertical was trying expand but,it looks like that won't happen till I do the recap. This set does not use a vertical output transformer, direct drive to the vertical deflection coils.

EdKozk2
03-01-2018, 03:08 AM
Well after recapping three RCA tv's in January, KCS-28,45,and 47 chassis I started on the Motorola TS-16A chassis. This set has turned out to be a great learning experience. The TS-16/16a and TS-30/30a chassis sets from 1949 were the only sets to not use vertical output transformers for a magnetically deflected CRT. This chassis uses a 35Z5 damper tube with a hum control, an audio squelch circuit,and a high voltage regulator circuit for the crt.
After recapping I started testing the set and found I had intermittent HV of 8Kv. This set uses two 1B3s, doubler. It was also red plating in one of the two 6BQ6 horizontal drivers. The problem was the 3 wire horizontal blocking transformer. It had an open winding. I opened up the transformer and was luckily able to re-solder poorly scrapped magnet wire.
With the horizontal oscillator now working, I measured 12KV at the anode lead.
Only trouble was I still was't getting any light or raster of any kind on the crt. I use a 5AXP4 for testing. All the voltage to the crt tested fine except one, the G2. Turned out the B+ boost voltage for G2 was not being boosted. This set used a selenium rectifier to boost B+ for G2 only, I had to replace that too. After the boost fix , I finally was able to get a bright horizontal line, but no raster still. I limit the mains voltage when I first start up a set.
I started checking the vertical oscillator and output tube circuit on the scope. Wave forms were fine even at 6BQ6 vert. output. Now I was worried the problem may be the deflection coil. I unplugged the yoke and found the 2 vertical windings to measure 43k ohms in series. They should have read 920 ohms in series. The horizontal windings were OK. They read 21 ohms.
After doing some checking, I found this chassis seems to have a one of a kind deflection yoke. None of the coil manufacturers' lists a cross of any type.
In a last ditch effort, I decided to cut open the cardboard yoke cover to see if maybe a wire came loose.Some of the vertical coil wires were corroded or broken. I was able to repair one section of the vertical windings but the other was broken some where in the windings.
With one vertical winding section still intact, I took inductance and resistance measurements, with the 36k ohm shunt removed. One section of vertical coil measured 382 mh and 463 ohms. I also measured the horizontal coils. They were 7.24 mh and 10 ohms each. These vertical and horizontal measurements were with an iron core yoke.
Needing a yoke with a vertical inductance of about 800 mh and horizontal of
about 16 mh, left me only a few choices since I wanted to get this set working again. I could re-wire all the vertical and horizontal circuits to match a latter version of this chassis, a TS-67, or try and rewind the vertical coils of the yoke. I decided to try and re-wind the yoke.

EdKozk2
03-01-2018, 02:36 PM
Continued:

I slowly took the coil apart to avoid breaking any coil wires. The original internal tie points were riveted to a paper band. The paper was so dry,it just crumbled to pieces when touched. After taping off the wires and removing some layers of tape I got to the iron core which surrounds the windings. The iron core is nothing but annealed black steel wire. The old core was very rusty and weighed about 6 ounces.
With the iron core removed along with some more tape layers, I reached the now exposed vertical deflection windings. Fortunately the vertical windings are covering the horizontal coils, which I didn't want to remove.I used plastic tools to pry loose the old vertical coil. I didn't want to damage the horizontal coils underneath.
With the vertical coil and iron core removed I re-measured the inductance of the still intact vertical and horizontal coils. The vertical coil has an inductance of about 266 mh. The horizontal coil is 5.5 mh per section. I now had a starting point from which to wind the new vertical coils. I decided to do both vertical coils, since I didn't know what caused the original coil break, stress or corrosion.

AlanInSitges
03-01-2018, 04:06 PM
You're a braver man than I. It never even occurred to me that you could rewind a yoke. Here's hoping it comes out OK, that is an interesting and beautiful set.

Radiotronman
03-01-2018, 04:37 PM
Thatís really a nice looking set. Thatís one of the high end Motorolaís of itís day where both big yellow knobs light up!

kvflyer
03-01-2018, 04:56 PM
Gosh, what a labour of love! I applaud your efforts and sincerely hope it works out. Please continue the pictures and let us know how it goes.

bandersen
03-01-2018, 04:58 PM
I dug up the service info for this chassis and reviewed it. Very cool! I had no idea Motorola had a chassis with innovations like a regulated HV supply.

Unfortunately, that leads to oddball parts like the yoke. Good luck with the rewind. I think it will be worth the effort to bring this set back to life.

EdKozk2
03-01-2018, 05:26 PM
Continued:
I flattened out the defective coil to roughly determine the inside and outside perimeter dimensions. The approximate thickness of the thickness was a 1/4 inch. I cut a 2.125 x 2.375 x .25 plastic form for a bobbin center. Cut some acrylic squares for bobbin ends and screwed it altogether.
I wound a practice coil first with 38 gauge wire. I used enamel wire gauge resistance charts to calculate the amount wire to use for the winding. I based the coil size on the rough flattened old coils' dimensions. After I finished winding the coil, I checked its' resistance and inductance; 345 mh and 725 ohms. This first coil wouldn't work I realized. The inductance and resistance were too great. I was worried about the maximum current the coil could handle also.
I had to order a pound of 36 gauge wire to wind the coil with since it could safely handle 70 ma. I over wound the second coil by 125 percent. Ended up using the extra wire to wind a duplicate vertical coil.
The motor I use for winding runs at 72 rpm. I calculated the average length per turn of the coil to be 10 inches. This gives 720 inches or about 60 feet per minute. The resistance per foot of 36 gauge magnet wire is about 0.413 ohms per foot. With a needed resistance of about 463 ohms divided by 0.413 ohms/ft , I came up with at least 1122 feet of 36 gauge wire. Took the 1122 feet of wire divided it by 60ft/min , comes to about 18-19 minutes of winding at 72 rpm.
In the end I ended up with two coils measuring about 265 mh with a resistance of 470 ohms each.

EdKozk2
03-01-2018, 06:51 PM
Cont:
To set the new coils in place I used some double side tape. I tried to position each coil toward the front of the yoke, to help maintain the vertical deflection angle. I marked center lines on the coil and yoke to maintain the 90 degree magnetic field between the horizontal coils. Next I used plastic tape, vinyl tape,and finally black duct tape to cover the coils. I wound over 8 ounces of 24 gauge black wire over tape. The black wire core is connected to ground.
Tap was wrapped over the black steel wire to prevent shorting of the coil connection tabs. I used some old belt sander fabric to replace the original paper
band for connections. The fabric doesn't burn up from soldering. Wrapped 2 turns of friction tape under the fabric terminal band to keep it from slipping. Friction tape was also taped to the underside of the terminal band.
I soldered all eight coil wires, resistors and capacitor in close to the same positions they were originally found. I cut some flat black pvc? plastic to replace the old cardboard yoke housing. I heated the plastic in a can over the stove a few seconds to reform it into a cylinder.
After I got the coil re-assembled, its' diameter had increased an eighth, but it still fit into its' mounting bracket. I just needed a longer and slightly deformed retaining screw.
With the repaired coil installed I started the testing, monitoring voltages, heat and sounds if any emanating from the yoke. Every seemed OK.

EdKozk2
03-01-2018, 07:11 PM
Some more pictures.

EdKozk2
03-01-2018, 07:45 PM
These pictures are the results of where I'm at so far, image, quality wise. I still have to clean contacts in the tuner, tubes sockets, and pots. I changed the 108 ohm (measure) cathode resistor of the vertical output tube to increase the raster height. I'm able to get almost full crt coverage. I may have to make adjustments to the vertical linearity RC time constant yet. The set does not have a vertical linearity pot.
I may have to make up a new 16 inch diameter plastic insulator for the crt. The old one was cracked, allowing the semi circular steel threaded strap to ground out the 16AP4. Amazing this didn't cook the flyback.
Ed

IsthmusTV
03-01-2018, 07:57 PM
Truly amazing work, Ed. Very impressive! You are giving new life to an unusual set with a yoke made of unobtainium.

Congrats!

Clark

Crist Rigott
03-01-2018, 10:03 PM
Nicely done!

Electronic M
03-01-2018, 10:13 PM
Impressive work! The Zenith vert out transformer I did by hand did not want to work perfectly with the original circuit RC values either...Next time I do something like that I've got to follow your lead and use a motor to wind...18 minutes sure beats my pace.

old_coot88
03-01-2018, 10:18 PM
Words like Amazing, Fantastic, Gobsmacked don't do justice here. Just hafta do the jaw drop thingy. :jawdrop:



:tresbon::banana:

EdKozk2
03-01-2018, 10:55 PM
Thanks everyone for the kind comments.
Now only time will tell how long the yoke will last.
Ed

Tom, I didn't realize you hand wound that transformer.:sigh:
It took me long enough just to unwind the steel core.

Phil Nelson
03-02-2018, 12:07 AM
Zowie! I have never heard of anyone successfully rewinding a yoke.

Thanks for documenting your process with text and photos. Someday, someone else may be able to follow your lead and save another vintage TV.

I'm usually allergic to combos with doors, but I'll make an exception for your classy looking blonde cabinet.

Phil Nelson
Phil's Old Radios
https://antiqueradio.org/index.html

dieseljeep
03-02-2018, 10:42 AM
Thanks everyone for the kind comments.
Now only time will tell how long the yoke will last.
Ed

Tom, I didn't realize you hand wound that transformer.:sigh:
It took me long enough just to unwind the steel core.

The insulation on the magnet wire of today is a lot better than that of 68 years ago. Plus you're not going to subject it to temperature extremes and humidity of years ago.
I've been exposed to old TV sets for something like 60 years, especially Motorolas, but I never seen or worked on one of those chassis. Really some strange circuitry. Almost the same chassis that Bob Anderson worked on.
BTW, that yoke must use the same steel wire core instead of the ferrites.
I only saw one of those. IIRC, it was from an early RCA. :scratch2:

Tom9589
03-02-2018, 01:46 PM
Kudos to Ed. I once wound a yoke for a vidicon camera. Fortunately, I had a buddy who had a coil winding machine he built, complete with a turn counter. I used very thin (3/16") plywood for forms. The counter came in very handy when I wound the focus coil. It had 5600 turns!

Is there a link for the schematic? I would really like to see these interesting circuits.

bandersen
03-02-2018, 02:38 PM
Here are links to sections of the schematic showing the vertical output and the HV regulator.

That 35Z5 damper with hum control is another oddity

https://flic.kr/p/224WWzJ

https://flic.kr/p/23sRc4V

Tom9589
03-02-2018, 03:46 PM
Wow. Thanks, Bob. These circuits look like something from a DuMont set. And 37 tubes between the TV and radio!

Electronic M
03-02-2018, 07:23 PM
Thanks everyone for the kind comments.
Now only time will tell how long the yoke will last.
Ed

Tom, I didn't realize you hand wound that transformer.:sigh:
It took me long enough just to unwind the steel core.

Twas ~100 turns a layer and each layer had an insulative wrap something like onion skin between it and the next layer. I used thick shopping bag strips for the new insulation.

The stupid part was it was a only a primary to secondary short...It may have worked fine if I had the presence on mind to unground the one yoke lead before I started the rewind work.

old_coot88
03-02-2018, 08:40 PM
Here are links to sections of the schematic showing the vertical output and the HV regulator.

That 35Z5 damper with hum control is another oddity

https://flic.kr/p/224WWzJ

https://flic.kr/p/23sRc4V

Wao.:eek: Talk about engineering overkill. Sorta like Muntz in reverse.

Notimetolooz
03-07-2018, 12:53 PM
I'm very impressed!
Although I'm not a fan of duct tape in permanent construction.

EdKozk2
03-07-2018, 11:02 PM
These are a couple of pictures with the rebuilt 16AP4A that came with the set. First is with the focus coil disabled. The second is with the focus coil connected to a separate power supply.
The crt wouldn't focus so I checked it out of circuit. I spent a day going over the focus circuit, everything matched the schematics, even the red and blue focus coil wires to the plug connector. This set I found had the wire connections inside the focus coil itself backwards.
I also used this chassis to test another 16AP4A crt today that came out of a Motorola TS-52 chassis I bought in the late eighties. Those are the last two pictures.
If any one else ever comes across a the TS-16/16a chassis, you can find an entire description of its' circuits starting in Riders Volume 5-8 for Motorola. I used a Teleaides for the schematics, better than the Sams for this chassis.
Ed

Bill Cahill
03-10-2018, 12:29 PM
Does anyone have an extra of that set they'd like to get rid of? That is the niftiest set I've ever seen. Even a hv regulator. Wow!

Bill Cahill
03-10-2018, 01:03 PM
Gee. I've never seen re build work like that in my life. It is utterly magnificent.I couldn't do work like that.

Kevin Kuehn
03-11-2018, 04:20 PM
Hey Ed, nice work on the Motorola. That was a pretty incredible undertaking rewinding the vert yoke coil. I'd probably of had that thing tied in a knot before I got it back on the yoke form. CRT picture is shaping up nicely. :thmbsp: