01-04-2017, 08:31 PM
Well, it has been a year now since I finished the radio.
Now I have a problem with it. It blows the mains 2 1/2 amp fuse. I pulled the chassis and the speaker and put them on my bench. I hooked it up to my Variac which has a voltmeter and ammeter. When I get to about 50vac the ammeter starts to climb slowly. At 60 volts it goes past 1 1/2 amps and then I shut it down. Then I pulled the 5Z3 rectifier tube and then I can go to full voltage with out any problems. I checked the 5Z3 and it checked good. They way the ammeter operates, it almost seems that a capacitor is breaking down and slowly conducting to ground. I pulled all the other tubes just in case it was a tube, but it still does the same thing.
The radio played well for about 9 months. Then one day it blew a fuse on turn-on. OK, I replaced the 1 1/2a fuse and a week later it blew it again after playing for a while. OK, in goes a 2 1/2a fuse. It played for about 30 seconds and blew. This is about how long it takes for the ammeter on the Variac to get up to 2 1/2 if I left things go.
I pulled the cans off the main filter caps, 103 & 104 and they look OK. I then tried it again with the 5Z3 installed and sure enough after about 30 seconds and 50 to 60 volts, the ammeter slowly climbs and I turn it off at 1 1/2 a. I checked the power transformer, the choke, the electrolytics to see if anything felt warm. Nothing.
So I'm asking what would be a good method of trouble shooting this thing. I do think it is a capacitor that is going bad, but that is just a hunch. Would disconnecting an electrolytic, one at a time cause any harm? Maybe I can find a bad electrolytic that way. Any pointers would be appreciated.
Thanks.
Crist
PS. The thread on restoring this console ended up in the Restoration Notebook Section. If this post is incorrect then please delete it moderator.
Now I have a problem with it. It blows the mains 2 1/2 amp fuse. I pulled the chassis and the speaker and put them on my bench. I hooked it up to my Variac which has a voltmeter and ammeter. When I get to about 50vac the ammeter starts to climb slowly. At 60 volts it goes past 1 1/2 amps and then I shut it down. Then I pulled the 5Z3 rectifier tube and then I can go to full voltage with out any problems. I checked the 5Z3 and it checked good. They way the ammeter operates, it almost seems that a capacitor is breaking down and slowly conducting to ground. I pulled all the other tubes just in case it was a tube, but it still does the same thing.
The radio played well for about 9 months. Then one day it blew a fuse on turn-on. OK, I replaced the 1 1/2a fuse and a week later it blew it again after playing for a while. OK, in goes a 2 1/2a fuse. It played for about 30 seconds and blew. This is about how long it takes for the ammeter on the Variac to get up to 2 1/2 if I left things go.
I pulled the cans off the main filter caps, 103 & 104 and they look OK. I then tried it again with the 5Z3 installed and sure enough after about 30 seconds and 50 to 60 volts, the ammeter slowly climbs and I turn it off at 1 1/2 a. I checked the power transformer, the choke, the electrolytics to see if anything felt warm. Nothing.
So I'm asking what would be a good method of trouble shooting this thing. I do think it is a capacitor that is going bad, but that is just a hunch. Would disconnecting an electrolytic, one at a time cause any harm? Maybe I can find a bad electrolytic that way. Any pointers would be appreciated.
Thanks.
Crist
PS. The thread on restoring this console ended up in the Restoration Notebook Section. If this post is incorrect then please delete it moderator.
Crist
