Band switch and tuning cap installed.
More progress.
Note the video on "what to do with an open Candohm resistor.
I am thinking about what to do with mine. They are not exactly open but some sections drifted (I alwasy wonder how a wirewound can drift). Considering paralleling resistors to the sections that drifted.
Well, they will test like they drifted. The problem is not usually with the resistance wire - though it can burn open. Rather with the crimped on connections getting intermittent due to corrosion or other poor contact. This is why people worry about using the terminals to mount a new resistor. They can make contact again. This process insures that will not happen.
Great idea Russ! That's a beautiful restoration on the chassis, I'm sure it will be a beauty when finished.
Great job and the info you provide while doing the restoration is going to be valuable to future restorers.
Russ, I want you to know how much I appreciated you sharing this restoration with us! "WOW" is an understatement!
I have learned a lot from your pictures and write up. Myself, I am still 'new' at restorations, and have a lot to learn. I was (and still am) a 'repair guy', which is quite different from fully restoring. I am trying to finish one of my early restoration attempts, which pales in comparison to that beautiful Zenith! I could go on and on, but more than anything - thanks! Good work!
Thanks guys (& all). Still waiting on a set of NIB tubes getting here prior to alignment.
It is done. Video posted.
Fantastic job Russ! How many hours would you say it took to complete?
Gregb
Very impressive work Russ
(06-11-2017, 01:03 PM)gregb Wrote: [ -> ]Fantastic job Russ! How many hours would you say it took to complete?
Gregb
I don't know. It was certainly, days. But, for sure, much less time than the first one (mine).
While Jeff's radio is on the bench, I have pulled my chassis to make some updates. My chassis had more missing parts(replaced an/or just missing) than Jeff's had. From his I was able to scan the cap boxes and make new replacements of the 4 original ones. Not having to pull all 3 speakers and the power amp makes things WAY easier for testing my chassis.
I also did some measurements on the 45 tubes' voltages and found them running near 400V (plate, against 330V normal) with a 75 volt bias (against 61V normal) but a proper 2.5V filament. The shop's power line transformer has been turned down to 119V. So the voltage is higher most everywhere else. Even with the higher bias, the B+ is too high. I am building two 10ohm 100W line dropping resistors - on heat sinks. My goal is to drop the line to less than 110V.
There are some notable differences between the 2nd run and third run chassis with significant changes not included in the version II schematics (I have never seen a version III schematic).
Russ
What's wrong with a Variac, if only for testing? And then, if this is a problem, you could put in a bucking xfmr? Doesn't even have to be large.
Well it draws 350W so a variac is going to have to be large. And I want something permanent. Same with bucking transformer.
This adjustment will have to be permanent on both installations. I have already tested both chassis at 107V and all is OK.
I have adjusted the dropping resistor to be 6ohms at 100W but I have ordered a 150W.