11-27-2021, 04:07 PM
I thought I did not have 78 tubes.
Also I realized one of the 78 tubes was replaced with a 77 one.
When I damaged one 78 in the beginning, I thought I did not have any in stock and now I even thought of buying some. Then I looked at my bench plastic bins, and I have a whole bin-full of them.
So I picked three that tested like new.
Also on the photo you could see a 77 tube's (the one right under the two IF cans) grid wire is outside the shell; I am sure it should be inside.
So I put all the tubes in, made sure it started rectifying at about 50VAC, and then went to 110VAC.
There was hum in the speaker and it reacted to the volume pot wiper being touched.
I could hear aerial noise, but rotating the tuning cap at where the local station is did not result in reception, so I will have to look at the RF circuit.
But so far no smoke and AF working is a good sign.
PS. Of course it works. I came down to see why there is no reception and then it occur to me to check the band switch posiition. Sur'nuff, it was on some SW band. Put in the BC position, the radio clearly receives the local station.
PPS. Putting the heat shield to the wire-wound resistor in the back proved to be a bit of a challenge. When taking that off I did not feel like taking the resistor out, so I bent a side. Putting it back was not possible without taking the resistor out, so I straightened the bent side, took the resistor out and then the insulating washer that is in between the holder and the resistor's end (probably to stress-relieve the ceramic) disintegrated, having been burnt over the years. And I do not have a fibre washer in the house. So I searched far and wide and found a fibre bushing which was exactly the right size and the internal diameter, so I saw off a piece to make a washer, and then spent some 15 minutes hand-sanding it to the right thickness. Eventually it went in. So the under-chassis is done.
I turned the speaker towards myself when playing (the cone facing the bench top obviously affects the sound) and was pleasantly surprise by a good clean base.
Now to alignment.
Also I realized one of the 78 tubes was replaced with a 77 one.
When I damaged one 78 in the beginning, I thought I did not have any in stock and now I even thought of buying some. Then I looked at my bench plastic bins, and I have a whole bin-full of them.
So I picked three that tested like new.
Also on the photo you could see a 77 tube's (the one right under the two IF cans) grid wire is outside the shell; I am sure it should be inside.
So I put all the tubes in, made sure it started rectifying at about 50VAC, and then went to 110VAC.
There was hum in the speaker and it reacted to the volume pot wiper being touched.
I could hear aerial noise, but rotating the tuning cap at where the local station is did not result in reception, so I will have to look at the RF circuit.
But so far no smoke and AF working is a good sign.
PS. Of course it works. I came down to see why there is no reception and then it occur to me to check the band switch posiition. Sur'nuff, it was on some SW band. Put in the BC position, the radio clearly receives the local station.
PPS. Putting the heat shield to the wire-wound resistor in the back proved to be a bit of a challenge. When taking that off I did not feel like taking the resistor out, so I bent a side. Putting it back was not possible without taking the resistor out, so I straightened the bent side, took the resistor out and then the insulating washer that is in between the holder and the resistor's end (probably to stress-relieve the ceramic) disintegrated, having been burnt over the years. And I do not have a fibre washer in the house. So I searched far and wide and found a fibre bushing which was exactly the right size and the internal diameter, so I saw off a piece to make a washer, and then spent some 15 minutes hand-sanding it to the right thickness. Eventually it went in. So the under-chassis is done.
I turned the speaker towards myself when playing (the cone facing the bench top obviously affects the sound) and was pleasantly surprise by a good clean base.
Now to alignment.
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
