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 Post subject: Webster Chicago Model 80-1 Recording Problem
PostPosted: Jan Tue 19, 2021 3:02 pm 
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Joined: Dec Mon 21, 2020 10:30 pm
Posts: 5
Hoping that there is a Webster Chicago Model 80 expert on line here.

I have one that is eating my lunch. It plays well, but trying to record the sound is muffled badly or squealing.

I have done a recap and changed out resistors that are out of tolerance and replaced an open volume control.

I notice that only in record C7 gets so hot, it has shorted a new 400v cap. The oscillator coil measures 13 ohms across it so I don't think it's shorted.

I have 400 volts in record on pins 3 and 4 of the 6V6 and -15 volts on pin 5. The neon light is lit at all times.

My circuit differs from the 3 different schematics I have. This one has a 220K 1/2 watt resistor between pin 4 of the 6V6 and the red lead to output transformer and R10. It also has a .47uf cap from pin 4 of the 6V6 to ground.

Any ideas or suggestions?

Maury


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 Post subject: Re: Webster Chicago Model 80-1 Recording Problem
PostPosted: Jan Tue 19, 2021 11:12 pm 
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Joined: Nov Wed 30, 2016 7:35 pm
Posts: 11100
Location: Sunbury, Ohio 43074
Probably best to post up the schematic of the area in question. :)

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Preserving the hist. of electronics, one boat anchor at a time! :)
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 Post subject: Re: Webster Chicago Model 80-1 Recording Problem
PostPosted: Jan Thu 21, 2021 12:18 am 
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Joined: Dec Mon 21, 2020 10:30 pm
Posts: 5
The schematic is attached. My concern is with problems recording and C7 getting so hot it shorts out in record mode.

Thanks


Attachments:
Webster Chicago 80-1 schematic.pdf [1.01 MiB]
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 Post subject: Re: Webster Chicago Model 80-1 Recording Problem
PostPosted: Jan Fri 22, 2021 2:47 pm 
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Joined: Dec Mon 21, 2020 10:30 pm
Posts: 5
I've decided that I have invested enough time on this and will part out the recorder. If anyone needs parts, contact me by email: w5io@sbcglobal.net.


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 Post subject: Re: Webster Chicago Model 80-1 Recording Problem
PostPosted: Aug Tue 17, 2021 3:46 am 
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Joined: Jul Wed 14, 2021 8:51 pm
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I never know if it is appropriate for me to respond to a post like this with my own problems, rather than trying to help the original author with his. But it seems he has moved on, so hopefully not stepping on any toes here.

I have a Webster-Chicago model 80 that seems to be in pretty good shape. I have not done any re-capping yet, because I wanted to see if there was enough life left in it to bother. So I decided to power it up on the variac. The unit never pulled more than .75 amps. The 1 amp fuse was good.

I did hear some buzz or hum, but not terrible. I turned it on, and it seemed to be working. So I loaded up a spool of wire, and I could hear it on the speaker. I could also hear it out of the output jack. Everything seemed to be working except the microphone. When I tried to record, all I got was a screech. I tested the microphone on another recorder, and it works fine.

I am pretty much new to electronics. I am trying to proceed slowly and carefully. I know a complete re-cap is called for, which I plan on doing asap. I am just wondering what is causing the screech? Of the 4 schematics I have found, none completely correspond to what I am seeing in mine. So I am doing a bit of head scratching.


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 Post subject: Re: Webster Chicago Model 80-1 Recording Problem
PostPosted: Aug Tue 17, 2021 3:59 am 
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Joined: Nov Sun 29, 2020 5:59 pm
Posts: 279
Location: Northeast Illinois 60188
Just like in tape recorders, make certain that the record-play switch is clean and operating properly.
This switch completely changes the operation of the circuit, and any connection that is not solid can and will cause all sorts of strange problems including squealing and feedback.


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