1961? Zenith C845Y HI-FI AM-FM Tube Radio Issues

[vortalexfan]

Greetings everyone, I just acquired a 1961 vintage Zenith C845Y AM/FM tabletop radio that I had replaced almost all of the paper caps in it except 2 of them because they were in difficult to reach/access locations in the radio, and the radio tuner is extremely out of alignment, especially on the FM Band because stations that should be on the lower end of the tuning dial are showing up on the middle of the dial and stations that should be in the middle of the dial are showing up on the top of the dial and the stations that should be on the top of the dial are non-existent, also the audio quality coming out of the speakers isn't quite up to snuff to where i would expect the audio quality to be on this radio. What could be causing these aforementioned issues with this radio? I was thinking possibly the IF Alignment is way out of adjustment but I'm not sure if that would cause the lackluster audio quality issue, and more the dial alignment issue.

Any help would be appreciated.

Thanks.

[Electronic M]

Local oscillator alignment is usually what causes off frequency tuning, though if this has AFC try turning it off to verify local oscillator doesn't snap back to normal.... AFC takes detector voltage and uses it to pull the local osc to peak signal... If the AFC bus is wildly wrong it might be able to feign a non-existent local osc alignment issue.

Not a bad idea to atleast check IF pass band with a generator too.

[vortalexfan]

Originally Posted by Electronic M

Local oscillator alignment is usually what causes off frequency tuning, though if this has AFC try turning it off to verify local oscillator doesn't snap back to normal.... AFC takes detector voltage and uses it to pull the local osc to peak signal... If the AFC bus is wildly wrong it might be able to feign a non-existent local osc alignment issue.

Not a bad idea to atleast check IF pass band with a generator too.

Yes this radio does have AFC but it acts like its not working (or non-existent), The pointer itself also looks like it might be slighly off because when I turn the tuner knob the pointer at the bottom seems like its in the right spot but then at the top its way off, the weird thing about this radio is that it seemed like it might of been virgin (never touched electrically except to change some tubes.)
But then I saw that the retaining nut that fastened the tuning dial to the cabinet was missing which tells me that the chassis was removed at one point in time, but I don't think it was for component replacement (as all of the capacitors and resistors were original) I think it was to attempt an alignment (also the tuning string was broken going from the tuning knob to the pulley.)

So quite possibly someone attempted to do an alignment on this radio but didn't know what they were doing and screwed something up with the local oscillator adjustments and also the AFC circuitry.

I'm going to attempt to look into what you suggested and also the alignment as well, I'll need to see if I can find a service manual for this radio so I can find the alignment instructions.

[vortalexfan]

Does anyone have any experience with getting a broken diddle stick out of a IF Can Tuning Core? I'm asking because I was trying to do a realignment on this radio following the instructions in the Beitman's service data and everything was going good until I got to the third IF Can for the AM Section and then my diddle stick decided it wanted to break on me inside of the IF Can tuning core and I can't seem to get it out with just shaking the radio chassis. Do I need to disassemble The whole IF can to get it out? Or is there something easier to do?