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Well, the lack of HV turned out to be the 6Y6. I put in a new one and I got a solid 11KV. Maybe there's something to this cathode stripping theory after all. I hope not, I like to listen to the radio on this set and that biases the 6Y6 with the heater off.
With the higher HV the horizontal width is marginal. I have to turn the width control to the end. I tried the NOS 6BD5 that I thought killed the B- supply. I turned the width to minimum first. It gave me a raster, then as I turned the width up it would soon start to collapse. Eventually, even at a reduced width bad things started to happen. I wasn't sure if it was Barkhausen or breakdown. It caused static in the audio and looked scary enough that I immediately shut it off. The tube tests at 100% when it should test 70% if new.
I can improve the width by going to a 6BQ6. It's an easy change, but it would make it a bridge code B18 instead of B17. I'm not sure if I want the bridge to be different than the version stamped on it.
This and the 12AU7 are two bad tubes in one lot from AES. I can't blame them, but the next time I order any tubes I'll test them in circuit immediately upon receipt. I have a small stock of bottle shaped 6Y6's. I have two really good ones from eBay. Looks like I'll need to obtain a few more.
The focus is better, but when using a dot pattern it's clear that it's an astigmatism. I can correct it with a weak external magnet. The next time I have the CRT out I'll try degaussing the yoke support and play around more with the location of the focus magnet. If that doesn't work I guess I'll resort to mounting a weak magnet.
The photo is the plate of the horizontal discharge 12AU7 tube. The service manual shows a rounded sawtooth and it doesn't have the dip between the teeth that mine shows. Is this a problem?
John
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