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Originally Posted by old_tv_nut
I dunno - hard to believe you're getting anything with zero volts on all three audio IF plates and screens. Are you sure your meter probe (plus or ground) isn't loose or broken? If not, chase down that 135v on the high side of R213, 234, 218. Fix the obvious first (or find out it's really OK), then look for the mistuning.
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Thanks, I get normal readings from my meter on other tubes, including other 7-pin tubes. I'm using Pomona tube extenders to take the readings with the chassis sitting normally on the workbench. At one point, I thought the extender might have loose pins, but testing other tubes ruled that out.
I will do my best to check out the 135v line. On this set, the CRT is not supported by the chassis, so you can't just flip the chassis sideways and power it up. I carved a piece of stiff foam to support the heavy end while installing the CRT on the workbench. The service manual recommends building a CRT support bracket so you can set the chassis on its back panel and do powered-up tests. Ha-ha . . . maybe later!
I may be able to test some things by sliding one corner off the workbench and crouching underneath with a probe and a flashlight. In a couple of past projects, I went so far as to tack-solder a lead to a test point, turn the chassis back down and reinstall the CRT, then make a test. But that's a lot of hassle just for one reading.
Meanwhile, maybe I can learn something by checking passive components. I'm wishing, however, for one of those wonderful military boatanchor manuals that gives you a complete resistance chart as well as a voltage chart (can you spell SX-28? :-)