Having trouble

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Re: Having trouble

Post by Bill Cahill on Wed Dec 19, 2012 10:43 pm

Sounds like either a bad tube, a dirty tube socket, a dirty band switch, or, silver mica disease in I F transformers.
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Re: Having trouble

Post by Wildcat445 on Wed Dec 19, 2012 10:51 pm

Do you have a schematic for this radio?

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Re: Having trouble

Post by Patrick on Wed Dec 19, 2012 10:56 pm

What options are open to me to get this radio repaired? Do you think a novice could replace the capacitors in the IF transformer? How do I know which IF is bad? If I fail the radio has little value anyway. Right? I have the schematic but it is a little unsure as to what values are on which caps in the IF.
Wildcat445 - I have a VOM and a capacitor meter.

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Re: Having trouble

Post by Bill Cahill on Thu Dec 20, 2012 2:45 am

I still need to know the answersw to my questions. You are jumping the gun. I need to know more.
Got a model nuimber??
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Re: Having trouble

Post by Bill Cahill on Thu Dec 20, 2012 2:50 am

Are you sure the model is 823B??
This model isn't listed.
May I see a picture? What types of tubes does it use??
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Re: Having trouble

Post by Patrick on Thu Dec 20, 2012 9:26 am

Emerson 823 Series B is on the case. A picture can be seen at:
http://www.radioatticarchives.com/images/e/Emerson_823B.jpg
Emerson 641B uses the same chassis and schematic. Uses a 50C5, 12AT6, 35W4 and 4 - 6BJ6 tubes.

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Re: Having trouble

Post by Wildcat445 on Thu Dec 20, 2012 1:11 pm

This is a seven tube AM only radio? The 4-6BJ6's are used like maybe an RF amp, seperate oscillator and 1st detector and an IF amp?

I would suggest starting to measure B+ in this radio. Ahead of the volume control (from the antenna to the volume control). Another possibility is that something is going on in one of the 6BJ6's. Like an open when the tube heats. If you have a known good 6BJ6, subbing them one at a time and noting the effect might help. Measure B+ when the radio quits. If you suspect the IF transformers, measure the resistance on the primary and secondary windings with the radio off. Be sure these measurements agree with the service literature. Then measure B+. Find out if you have positive voltage on the tube grid following the IF transformers.

I agree with Bill. You are getting ahead of yourself. You have no information to work with yet. The only thing you know for sure about this set is that the tubes light and that the audio section works.

Regards

WC

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Re: Having trouble

Post by Patrick on Thu Dec 20, 2012 5:13 pm

Voltage measurements on all pins of all tubes seem to be reasonably close to what they should be. Subbing with a NOS 6BJ6 into all 4 sockets made no improvement. Resistance on both primary and secondary windings of both IF transformers with the radio off was a consistent 18 ohms. I don't know what they should be in the service literature. Voltage on the tube grid (12AT6) following the IF transformers was negative as it should be. Tubes have been subbed and tested, sockets have been de-oxidized, volume and tone potentiometers have been cleaned and there is no band switch.
It will be a shame but I'm getting closer to salvaging parts and shoving this radio into the garbage.

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Re: Having trouble

Post by Ben Delk on Thu Dec 20, 2012 6:01 pm

Patrick I call those paper weights. I have few but the guys here keep encouraging me to keep after them so I put them on a shelf until I feel froggy and want to jump back on them. I've only scrapped 2 and I bought them as parts anyway. When I get in the mood to scrap one I just put it on the shelf, find a quick fixer like "fiver" so I can feel good about what I'm doing and move on. I'm still a novice at this but most of my repair day are very enjoyable. Keep after it, it does get easier......somedays....

Ben
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Re: Having trouble

Post by Bill Cahill on Thu Dec 20, 2012 6:42 pm

You are measuring the wrong thing. In fact, in most cases, an ohm meter isn't sensitive enough to read that high a leakage.
The problem in the IF transformers is corosion that migrates between the capacitors on the primary to secondary.
That will cause no reception, then, loud static. When bad enough it goes to a hum.
At it's worse, I've heard a loud pop, and, fire shot out of the transformer.
I had that happen on a 1948 Philco.
When I was a teen someone gave me an old Admiral 1950 radio phono in a bakelite case. No. Actually, it was 1953.
I was going to plug it in, and, I saw a big burned streat on the copper plated chassis.
I looked, and, one of the IF transformers had caught on fire.
I junked the set.
Get Photobucket. It's easy to use. We can talk you through how to load the pictures from there to here. It's actually very easy.
Pictures can mean alot in helping you out.
Bill Cahill

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Re: Having trouble

Post by Patrick on Fri Dec 21, 2012 10:06 pm

Ben - that is probably the best advice I've had so far. With over 100 old radios in my house to renovate I think I will move on. Thanks to Wildcat and Bill for trying to solve my problems. I know I have at least learned more about this hobby.

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Re: Having trouble

Post by Ben Delk on Sat Dec 22, 2012 10:39 am

Patrick....there is a wealth of knowledge in this group but what you will find is it is difficult to translate what you are being advised to do when you have limited knowledge yourself. When you are trying to resolve an issue on something you are just learning about, one's ability to properly explain the issue is the key to that success. So, try to explain as well as you can what your issue is, follow the info these great provides give and then reply on each item. Bill has blog somewhere on this forum that gives a step by step process on how a radio receives and process a broadcast. I’ll try to find it but in the meantime look around for it.
Merry or Happy whatever one chooses to call it Holiday,
Ben
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Re: Having trouble

Post by Wildcat445 on Sat Dec 22, 2012 11:24 am

Patrick, if it makes you feel any better, it took me over 20 years to fix my Philco 116-B. I would work on it for a bit, get aggravated, push it to the end of the bench. Then I would work on it a bit, need an unobtanium part, and the search was on. But I got it all done, re-veneered the cabinet, refinished the cabinet. I have five times the money in it that it will ever be worth. But I fixed it. That fact alone made the project well worth the effort. I would highly recommend that you find a place on your bench for "problem children." Then as you gain experience or have a moment of great inspiration, you will fix it. Junking a set just because I cannot fix it is a practice that I early on would avoid like the plague. The tough cases are the ones you learn the most on. Hang in there, the fix is out there, and, eventually, you will find it.

Regards

WC

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Re: Having trouble

Post by Bill Cahill on Sat Dec 22, 2012 12:39 pm

And, I totally agree with Wildcat. Set it asside, go onto something else. That's what I do with my tough projects.
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Re: Having trouble

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