Does anyone have a Sams 91-A folder 13 they could part with? My Zenith Porthole set has developed a few problems and I need to test voltages. The TV was runnning fine after replacing all paper caps, Micamolds, Lytics and out of spec resistors. A few days ago I started hearing a buzzing sound coming from around the yoke I think. Swapped the yoke with one from a parts chassis but the same result. I've attached a screen shot that occurs when the buzzing starts. The vertical is very unstable and adjusting the vertical hold on the front of the set is very touchy, If I adjust too far one way or the other I lose Vertical deflection. Any help or thoughts would be greatly appreciated.
Thanks
Jim

I may have one. I'll have to look.I seem to remmeber, having set #91, and the suppliment, 91a.

I only have one porthole right now, IIRC, a 22h20, or something, BURIED in onne of my storage garages. It is in a blonde console cabinet.

classicradios,

I just scanned the schematic for you. It is very legible. The only thing is the files are large. One is about 8.5 Meg and they are in a PDF format. E-mail me if you want the scans.

shyone1@sbcglobal.net

classicradios,

I also appear to have the Rider's TV Volume covering your chassis as well. I will try to scan it this weekend.

Ross

Problem Solved.
Had an open 470K resistor under the 1B3 Tube. That solved it, The sets running great again. Would still like to get a Sams Folder on this chassis if anyone has an extra.
Thanks
Jim

Thanks. I'll remember that. I was going to guess something in vertical sync circuit, though, it wasn't really rolling. By the way, found that in 16" Zenith, and RCA tv's, h.v. cap on 1B3 tends to short, and start arcing. I am sure your know, but, in case someone doesn't, these sets ran on a voltage of 115-117 volts a.c. Our present 125 volts makes these sets run extra hot, and B+ is often very high. To cut this, I put an appropriate wattage resistor between rectifier, and first filter. That puts B+ in better ballpark, but, then, of course, tube filaments are usually 6.3, and the higher voltage, depending on set, can put voltage as high as about 8 volts. This could also be what made your hv resistor fail.