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I'd start by changing the filter capacitors. Sometimes they make a set sound garbled like that, as if the speaker was torn and "blowing in the wind".

Now if I only knew what a filter capacitor was and what it looked like!

It's the big ones :)

If those are bad, it will almost sound like the set has a putt-putt sound coming from it, commonly referred to as "motorboating".

Value of them will be somewhere around 30-50 uF @ 250-350V

Not a tube? It's got big square metal things sticking up sorta around the tubes. Is that them?

Quote:

Originally posted by dsk
Now it sounds like crap (it may have before, I really didn't listen to it). It sounds like a speaker is blown, although I don't think that is the case, I'm just trying to describe the distorted sound. Could it be a tube?

The first thing I'd check would be the electrolytic filter caps, if you're hearing hum with the sound. However, since you didn't go into specifics about how your C845 "sounds like crap", I can't say a whole lot more. One of the speakers could have a jammed voice coil, but if it were open you wouldn't hear anything at all from it. I would also make sure the speaker cones aren't torn or otherwise damaged; this can and often does cause distorted sound in radios (and TV sets as well).

The audio output tube could be gassy or shorted; if the latter, however, your set wouldn't work at all, since a shorted tube in a series filament string will remove filament voltage from all tubes following it and will cause every tube before the shorted one to glow brighter than the rest (as they are now being forced to operate with more voltage than that for which they were designed), and one of them will burn out if the set isn't shut off in a hurry.

Quote:

Originally posted by dsk
Not a tube? It's got big square metal things sticking up sorta around the tubes. Is that them?

The square metal things probably house your IF transformers. Stay away from these. The filter capacitor is usually contained in a cylindrical metal or cardboard canister mounted atop the chassis. It will have from two to four sections -- I.E.: 40-40-60 mfd. It's usually best to disconnect this multi-section unit electrically (leaving it mechanically intact), and replace it with several modern individual electrolytic capacitors, beneath the chassis.

I had a Zenith 7H920 that was sounding a lot like the way you are describing. It turned out to be a defective tube: a 19T8 AM-FM detector/audio amp. I would definitely check out the tubes before going too far.

Paula