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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Zenith model 1203 "Tombstone" radio, (1938 I think)
I'm helping a friend with this. I was over to his house the other night and he was showing me this beautiful old console radio. He told me that he had paid someone to restore it some years ago. He said that among other things they recapped it. The radio sounds great with a surprisingly really hot front end. The only problem is that the volume will only go down so far. In looking at the schematic as I had feared the volume control R12 is a 2 Meg ohm part and looks like a tapped control with four connections on it. Where exactly they'd tapped that thing is anyone's guess.
We haven't pulled the chassis yet but I'll bet that either the control is bad or some homyok changed it, either eliminating the tap or Rube Goldberg'd another one. From the sound of it somehow that wiper, which goes through a cap to the control grid of the 1st audio is not seeing ground when the control is turned fully CCW. If I need to I'm sure that I'll be able to come up with a control in my junk box with an audio taper somewhere between 500K and 2 Meg that would work, however the question is that tap. Can anyone venture a guess as to how far up from the low side of the wafer, (or down from the high side of the wafer) that tap would be? Thanks, Lenny |
#2
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Zenith model 1203 "Tombstone" radio, (1938 I think)
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#3
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Zenith model 1203 "Tombstone" radio, (1938 I think)
On Tuesday, May 27, 2014 9:31:51 PM UTC-4, wrote:
I'm helping a friend with this. I was over to his house the other night and he was showing me this beautiful old console radio. He told me that he had paid someone to restore it some years ago. He said that among other things they recapped it. The radio sounds great with a surprisingly really hot front end. The only problem is that the volume will only go down so far. In looking at the schematic as I had feared the volume control R12 is a 2 Meg ohm part and looks like a tapped control with four connections on it. Where exactly they'd tapped that thing is anyone's guess. We haven't pulled the chassis yet but I'll bet that either the control is bad or some homyok changed it, either eliminating the tap or Rube Goldberg'd another one. From the sound of it somehow that wiper, which goes through a cap to the control grid of the 1st audio is not seeing ground when the control is turned fully CCW. If I need to I'm sure that I'll be able to come up with a control in my junk box with an audio taper somewhere between 500K and 2 Meg that would work, however the question is that tap. Can anyone venture a guess as to how far up from the low side of the wafer, (or down from the high side of the wafer) that tap would be? Thanks, Lenny One end of the pot,(it seems like it must be the low side) looks like it does go through a capacitor then through what I think is a tone switch and then through a small value of a multi section resistor to ground. I wonder if that section of the resistor was open if that could cause my problem? Lenny |
#5
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Zenith model 1203 "Tombstone" radio, (1938 I think)
On Wed, 28 May 2014 04:56:29 -0700, amdx wrote:
...snip.... If you go to this Antique Radio forum, there are many there that will have the info you need. You will need to sign up to post, but it is harmless. Very good forum! It covers more than antique radios. http://www.antiqueradios.com/forums/index.php Mikek Thanks for that URL! I still have the FIRST radio I ever fixed, one of those 5 band console pieces of furniture. So it's good to know I have a place to go ask for help to keep it a bit like it was made. ...right now there's a 1 inch hole cut in the speaker [had to] but you know those old speakers. You could nibble away at tears and they still worked pretty well. I always hated the bass boost sound, but my grandfather was so used to that sound that he asked to borrow the radio and kept it for years until his passing. He loved his 'farm reports' news stations. Never liked listening to them through a modern sound system. |
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