Motorola 16VF8

[EdKozk2]

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.