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 Post subject: Webster Chicago Model 80-1 Schematic vs. Installed Component
PostPosted: Jan Sun 26, 2020 11:52 pm 
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I'm looking for some help in trying to determine some components I'm finding in my 80-1 wire recorder that are not showing up in the schematic I downloaded. The schematic is a Sam's Photofact from 1948 and it's labeled "Webster 80-1". However, one of the issues I have is that coming off pin 6 of the 6SJ7 tube is an 18k resistor to ground. Installed in my 80-1 was a 47k to ground, and based on the soldering, it looks original to the unit. Next, I have a third can cap installed that's labeled "1.0uF 300vDC" but I can't find that cap listed anywhere in the schematic. Oddly, there are 2 leads coming from this cap, and I'd expect to see the cap labeled something like "1uf 300vDC x2" if both leads went to two 1uF caps inside the can. One lead of the cap goes to pin 3 of the 6J5 tube, which then has a 39k resistor to a 15uF electrolytic to ground. I'm not seeing a 1uF anywhere. The schematic I have shows a 1.73mmF connected to pin 3, but that comes out to .000001uF... certainly not 1uF!

Anyway, the second lead of this 1.0uF cap goes to a pin on the "Listen/Record" switch.

Can anyone shed some light on this for me? I've been going over this schematic and comparing it to my 80-1 for almost two hours and I'm getting bug-eyed.

Thanks very much.

Aaron


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 Post subject: Re: Webster Chicago Model 80-1 Schematic vs. Installed Compo
PostPosted: Jan Mon 27, 2020 2:07 pm 
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Joined: May Sat 06, 2006 4:03 am
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Location: ZIP 23831 South of Richmond, VA 25 miles down the pike.
SAMS number?

Bill J.


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 Post subject: Re: Webster Chicago Model 80-1 Schematic vs. Installed Compo
PostPosted: Jan Mon 27, 2020 2:40 pm 
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Joined: Dec Sat 17, 2016 5:47 am
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There's no number indicated. It just says "Webster 80-1" in the upper right corner. At the lower-left corner, it just says "A Photofact Standard Notation Schematic, Howard W. Sams & Co, Inc. 1948." I've attached it to this post.
Thanks.
Aaron


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Webster-80-1.jpg
Webster-80-1.jpg [ 367.73 KiB | Viewed 2028 times ]
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 Post subject: Re: Webster Chicago Model 80-1 Schematic vs. Installed Compo
PostPosted: Jan Mon 27, 2020 3:35 pm 
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That 1.73 mmf is a typo. There was a discussion here: https://www.antiqueradios.com/forums/viewtopic.php?p=2108795


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 Post subject: Re: Webster Chicago Model 80-1 Schematic vs. Installed Compo
PostPosted: Jan Mon 27, 2020 4:01 pm 
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Joined: May Sat 06, 2006 4:03 am
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Location: ZIP 23831 South of Richmond, VA 25 miles down the pike.
I took a look at Model 79 on Nostalgia Air which claim is same as Model 80 just to compare. But it's different beast. It indicates a 6SN7 instead of 6J5. Sorry, no help there. I would stick with the wiring as it is if you can be assured it's factory.

Bill J.


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 Post subject: Re: Webster Chicago Model 80-1 Schematic vs. Installed Compo
PostPosted: Jan Mon 27, 2020 4:04 pm 
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Location: Lawrenceville, Illinois 62439
Might be Sams 37-26 (mine is missing from my 37 folder :oops: )
Dan


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 Post subject: Re: Webster Chicago Model 80-1 Schematic vs. Installed Compo
PostPosted: Jan Mon 27, 2020 4:28 pm 
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Thanks for the reply. I did indeed see that original post. But unless I missed it, I didn't see anywhere the fact that the 1uF/200vDC can cap has TWO leads coming from it. I hate to assume anything, but it looks like I need two 1uF caps in order to make this right.

Finally, are there any thoughts on the 18k resistor shown in the schematic, but there's a 47k actually in the unit? I'm referring to resistor number 20 on the Sam's schematic.

Aaron


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 Post subject: Re: Webster Chicago Model 80-1 Schematic vs. Installed Compo
PostPosted: Jan Mon 27, 2020 7:16 pm 
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In the link I posted above, there's a picture that's posted - it looks like a 47k going from pin 6 to pin 1 (ground). It might be the same as yours?


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 Post subject: Re: Webster Chicago Model 80-1 Schematic vs. Installed Compo
PostPosted: Jan Mon 27, 2020 7:33 pm 
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Yes. Exactly the same. But since it's been an established fact that the "1mmf" cap is a typo, is the "18k" resistor at number 20 in the Sam's schematic a typo as well? One of the biggest reasons I'm trying to be as accurate (and thorough) as possible is that whenever I restore something like this, I always keep careful notes and annotated photos to accompany the notes. In this way, anyone who may work on the unit well into the future will know of any updates or modifications I made. If the schematic is showing an 18k but there's a 47k installed, I want to make sure folks will know why and the schematic I have is updated accordingly.


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 Post subject: Re: Webster Chicago Model 80-1 Schematic vs. Installed Compo
PostPosted: Jan Mon 27, 2020 7:44 pm 
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There's another strange cap in there - with a lead soldered to its metal shield. Maybe that's the one you're talking about? There's been discussion about that one. Do a search for webster shielded on the forum.
I have an 80-1 myself and it's not restored yet and I can't access it right now.


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 Post subject: Re: Webster Chicago Model 80-1 Schematic vs. Installed Compo
PostPosted: Jan Mon 27, 2020 8:55 pm 
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Yes. I came across two of those on my 288-1 Webster wire recorder. It's simply a .01 cap (if I'm not mistaken) with a shield around it. I was able to remove the old wax cap from the metal shield and insert a new .01 inside the shield. I put heat-shrink on both of the leads, then filled in the empty space at either end with hot glue since the new cap is much smaller than the original. I replaced two in my 288-1 and they seemed to work perfectly. I did the same with the 80-1.


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 Post subject: Re: Webster Chicago Model 80-1 Schematic vs. Installed Compo
PostPosted: Jan Mon 27, 2020 11:05 pm 
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Looking around in my files I found a service manual for models 79, 80.
There is note in there about changing that resistor to 47k. There's also a note about that cap value being changed to 1.0 mfd, 200v.
You can download it here (you have to play the I'm not a robot game). https://elektrotanya.com/webster_79_80_wire_recorder_huzalos-magnetofon_1947_sm.pdf/download.html


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 Post subject: Re: Webster Chicago Model 80-1 SChematic vs. Installed Compo
PostPosted: Feb Sun 09, 2020 11:37 pm 
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I made the mistake of starting a new thread rather than keeping this one going. Now that the service manual I now have in my possession shows the typos I was seeing in my Sam’s schematic, I was able to recap the 80-1 and replace most of the resistors.

However, now that everything is finished, and it's working perfectly mechanically, there is not a single trace of sound coming from the amp; not even the slightest bit of hum. I tested the unit on my DBT and variance before going into the rebuild even though several of the caps clearly showed signs of failure. Even though the quality of the audio out was awful, it was there nonetheless.

I checked the speaker by feeding it independent of the amp and it's fine. I performed the two "amp tests" in the service manual and found that the amp IS working if I feed audio into the grid side the 68k resistor on the 6V6 tube. It's as if the amp is completely muted and I can't figure out where the problem could be. I've been over the schematic and compared my work dozens of times but I just can not find my error. The only possibility I can see, because it's a connection I removed and forgot to document, is the yellow wire that runs from the motor control switch. I have it going to the "RUN/LISTEN" switch, but I'm not sure if I put it back on the right terminal. I know what you're thinking; if I removed the wire from a terminal on the switch, why not just put it back on the one that's clean and missing solder? Simple, I removed a lot of the old solder on the switch because of the caps that needed to be replaced, and also because three of the terminals barely had any solder on them in the first place. I think this unit had been worked on once before. The bottom line is that I’m having a very difficult time trying to determine what I’m seeing on the RUN/LISTEN switch in the amp to what’s indicated in the schematic. Is the yellow wire the one shown coming off the “safety switch on mechanism” pictorial in the schematic?

I also removed the original output plug on the unit and replaced it with a 1/4” jack.

Finally, I checked the voltage and resistance measurements indicated in the service manual. About the only values that are spot on are the 3vAC readings on all the tubes. Everything else is WAY off from what is indicated. For example, I’m supposed to be getting 127vDC on pin 3 of the 6J5; I’m getting 144.5. On pin 3 of the 6V6, I should be getting around 300vDC but I’m getting 333vDC. Pin 5 of the 6V6 should be reading around -45vDC but I’m getting -8.1vDC. On pin 3 and 5 of the 6X5, I should be getting 350vAC, but I’m reading 308vAC. The RECORD/LISTEN switch is in RECORD when I’m making these tests.

As far as the resistance measurements are concerned, they’re all over the place. The measurements on the 6J5 tube are all reading 0... not what the service manual says I should be getting across the pins to ground. I tried four different meters and got the same results.

Sorry for the long post. I’m going in for surgery on my hand Friday morning and unless I can get this unit working sometime this week, I won’t be able to touch it again until autumn.

Thanks for any help.

Aaron


Attachments:
D0F5B067-AD2B-429C-AF0A-FF12D4D946AF.jpeg
D0F5B067-AD2B-429C-AF0A-FF12D4D946AF.jpeg [ 195.07 KiB | Viewed 1909 times ]
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 Post subject: Re: Webster Chicago Model 80-1 Schematic vs. Installed Compo
PostPosted: Feb Mon 10, 2020 6:48 pm 
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Looks like the yellow wire needs to go one lug over clockwise. Here's a pic of my 80-1


Attachments:
Webster 80-1 Run-Listen switch.jpg
Webster 80-1 Run-Listen switch.jpg [ 500.77 KiB | Viewed 1859 times ]
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 Post subject: Re: Webster Chicago Model 80-1 Schematic vs. Installed Compo
PostPosted: Feb Wed 12, 2020 3:05 pm 
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Thanks for sending the picture as it really helped. I moved the yellow wire to the proper pin but it didn't help. Still no sound coming from the amp. One thing I did notice is that with the RECORD/LISTEN switch in "record" mode, I get a hiss coming from the speaker. Switching between the two modes brings up a noticeable "pop" in the output to the speaker, but still nothing whatsoever in "listen" mode. I think, at this stage, I'm not going to have any choice but to remove the amp from the framework of the unit and attach some extension wires to the motor start switch and the pilot lamp socket. Working on the amp when one of the chassis rails is in the way makes troubleshooting very difficult.

Regardless, this is driving me nuts because I can't find any error in the placement of the caps and resistors I replaced. As I said earlier, the amp is working, but it's completely muted. I checked the leaf switches on the motor start switch assembly and they are making contact and are aligned as they should be according to the service manual.

Aaron


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 Post subject: Re: Webster Chicago Model 80-1 Schematic vs. Installed Compo
PostPosted: Feb Wed 12, 2020 5:12 pm 
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Sorry I can't be of much help. Any chance that when you replaced the output jack that the two wires were switched?


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 Post subject: Re: Webster Chicago Model 80-1 Schematic vs. Installed Compo
PostPosted: Feb Thu 13, 2020 4:44 pm 
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No worries at all. Thanks again for the picture you sent.

I checked the modified output jack and it is installed correctly. One thing I never considered is the head of the unit. Since I'm not completely familiar with how these wire recorders actually work from a sound point of view, I'm wondering if the amp relies completely on a signal passing through the oscillator coil in order to do anything. So even if the unit is running, if the head is damaged in any way (be it the wiring from the head to the amp or the head itself), would ANY audio be coming from the amp if there's no input signal to it? I'm thinking similar to how you can gently touch the needle of a tone-arm... and if the turntable isn't muted, you'd hear the noise of touching the needle through your amp. What's the best way to test the oscillator coil?

One thing I tried last night was to feed a signal from my audio generator to the input terminal at the amp where the shielded cable from the head unit connects to. I didn't hear a darn thing... which struck me odd, but again, without completely understanding the operational theory behind these wire recorders, I have no idea if that's an acceptable test.

If any other experts want to chime in, I'd really appreciate it.


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 Post subject: Re: Webster Chicago Model 80-1 Schematic vs. Installed Compo
PostPosted: Feb Fri 14, 2020 4:08 am 
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Good news. Just wanted to let everyone know that the 80-1 is now working. It turns out that the original component layout on the amp, compared to the actual “CORRECT” schematic was the tripping point. C3, the 1uF cap, has caused a great deal of confusion due to the typo in the SAMS schematic. The original 1uF metal can cap that was installed on my 80-1 actually had TWO leads on it. One was connected to a terminal on the RECORD/LISTEN switch which then went to a .05 cap on the OUTPUT switch; in this case, C5, according to the Webster Chicago schematic from the service manual.

The trouble is that I had this cap installed (C3), but one end was connected to ground. In order to duplicate what I thought was correct based on the old can cap, I installed a SECOND 1uF cap from pin 3 of the 6J5 to another pin on the RECORD/LISTEN switch. Basically, I thought I was duplicating what was already installed in the unit from the old can cap.

The problem came from that first 1uF cap to ground. It was shorting out the amp. I removed BOTH of the 1uF caps and installed a new one from pin 3 of the 6J5 to the terminal on the RECORD/LISTEN switch with the wire going to C5. Once I did that, the amp ROARED to life.

I hope what I described made sense, but for anyone who works on one of these in the future, don’t be fooled like I was by that 1uF metal cap. From what I’ve figured out, there are NOT two 1uF caps in the can; just one, but they’re connected together inside the can. One terminal on the can goes to pin 3 of the 6J5, while the other terminal is connected to C5. The case of the can is connected to ground, but the cap itself has NO ground connection.

Problem solved.

Aaron


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 Post subject: Re: Webster Chicago Model 80-1 Schematic vs. Installed Compo
PostPosted: Feb Fri 14, 2020 4:39 pm 
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Good to hear you got it working. I saved your post above for when I re-do my unit. Have fun with your hand surgery!

Mike


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