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 Post subject: Re: Arvin 8576, no reception
PostPosted: Aug Thu 27, 2020 12:25 am 
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Location: Palos Verdes, CA
When I got an Arvin 8576, it was completely dead and had seen a lot of use. The printed circuit board needed to be cleaned as I had difficulty in tracing the circuit. After connecting the Arvin 8576 to a 9 volt battery, I used a small screwdriver in order to check the solder joints and was surprised when the radio started to work. I re-soldered one of the connections that is just below the screw hole located at the top of the photo below and was able to tune in 4 stations. I didn't replace any of the components as I wanted to keep the Arvin 8576 original.


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Arvin 8576 PC board.JPG
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Arvin 8576 components.JPG
Arvin 8576 components.JPG [ 306.52 KiB | Viewed 224 times ]
Arvin 8576 components 2.JPG
Arvin 8576 components 2.JPG [ 336.34 KiB | Viewed 224 times ]
Arvin 8576 5 transistor radio.JPG
Arvin 8576 5 transistor radio.JPG [ 357.15 KiB | Viewed 224 times ]
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 Post subject: Re: Arvin 8576, no reception
PostPosted: Aug Thu 27, 2020 1:19 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 543
Location: moreno valley
Removed A4, the two shorts to ground on the traces that shouldn't be there went away. Pin 3 is shorted to 6 & 1, pin 3 to pins 2 & 4 are open. There's no 'can' on this one and the wires are all intact on top so apparently it is shorted/open inside. Well thanks everybody for the help, at least it got narrowed down to where it sure looks like the final problem was and the bad 2n94 is fixed. I'll put this 'dog' to bed for now and hope I can dig up another coil from a junked parts radio or something. Biggest transistor challenge I've had yet!


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118208875_3275017629246980_9003562537094029918_n.jpg
118208875_3275017629246980_9003562537094029918_n.jpg [ 157.52 KiB | Viewed 210 times ]
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 Post subject: Re: Arvin 8576, no reception
PostPosted: Aug Thu 27, 2020 1:28 pm 
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Location: Utica, NY 13502 (USA)
Congratulatons! I would never have expected that.

Dave


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 Post subject: Re: Arvin 8576, no reception
PostPosted: Aug Thu 27, 2020 3:38 pm 
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Two things that you could try...

Find another dead transistor radio that you have no desire to repair and scavenge the Oscillator coil (typically has a tuning slug painted red) and use it for repair of this radio. You will have to determine which wire goes where since they may not match the pin configuration. Alternatively there are people who sell the JW Miller 8813 transistor local oscillator coils but once again you will have to make sure which pin goes where because it may not match the pin configuration. Unfortunately I could not find a drawing of the 8813 pin configuration.

Best of luck,

Curtis Eickerman

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 Post subject: Re: Arvin 8576, no reception
PostPosted: Aug Thu 27, 2020 4:46 pm 
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Location: Palos Verdes, CA
Member Matt (50sTransistorRadios) mentioned in his youtube video that he had a parts Arvin 8576 and you may want to contact him to see if he still has it:

viewtopic.php?f=4&t=261487


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 Post subject: Re: Arvin 8576, no reception
PostPosted: Aug Fri 28, 2020 2:11 am 
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Location: Utica, NY 13502 (USA)
Here are the dimensions and pin connections for the Miller 8813. I added the red labels for emitter injection which your radio has.

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Miller 8813 Outside Dimensons.JPG
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Miller 8813 Pin Locations.JPG
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Miller 8813 Schematic.JPG
Miller 8813 Schematic.JPG [ 63.27 KiB | Viewed 186 times ]


Dave


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 Post subject: Re: Arvin 8576, no reception
PostPosted: Aug Fri 28, 2020 11:05 pm 
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Posts: 543
Location: moreno valley
So that Miller one would definitely work? Are those available new somewhere, a common part?


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 Post subject: Re: Arvin 8576, no reception
PostPosted: Aug Fri 28, 2020 11:19 pm 
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Location: Palos Verdes, CA
There are two sellers on eBay who have Miller 8813 coils and here is the one with the cheapest price:

https://www.ebay.com/itm/2-PCS-8813-JW- ... Swbb5eFOAH


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 Post subject: Re: Arvin 8576, no reception
PostPosted: Aug Fri 28, 2020 11:38 pm 
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Eickerman wrote:

Find another dead transistor radio that you have no desire to repair and scavenge the Oscillator coil (typically has a tuning slug painted red) and use it for repair of this radio.

As usual, Curtis gives excellent advice. I'll go a step further; if you are going to get into collecting and restoring Transistor radios, get several of the same era as what you'll be working on cheep, and keep them in your junk box for parts. Other than the Electrolytic's, everything else, antenna ferrite bar and coil, tuner and volume control, Transistors, resistors, disc capacitors, osc and IF cans, are spare parts.

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 Post subject: Re: Arvin 8576, no reception
PostPosted: Aug Sat 29, 2020 12:26 am 
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Location: Utica, NY 13502 (USA)
frenchmarky wrote:
So that Miller one would definitely work?
I don't know...I've never tried one. I merely stumbled on a site that had the pinouts.

My red labels are based on the fact that applying feedback to the emitter instead of the base would theoretically require a lower impedance as suggested by how your original coil is connected. Seems like swapping the ground and the variable cap connections on the 8813 would accomplish this. Maybe Curtis will chime in to confirm or debunk my thinking.

Dave


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 Post subject: Re: Arvin 8576, no reception
PostPosted: Aug Sat 29, 2020 4:55 am 
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I think I agree with the suggestions about 8813 coil connections with one exception. I think you would have to experimentally connect the un-tuned feedback link one way or the other to see which way provides the proper phase shift for oscillation (i.e. which terminal goes to the collector versus the IF transformer). Below is my understanding of how the 8813 pin numbers would correspond to the radio coil pin numbers.
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file.jpg
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Unfortunately this would mean some kind of adaptation would be necessary to use the 8813 coil since you could not just plug it directly into the existing holes of the circuit board and have it work. Remember to look at the 8813 drawing with regard to its pin numbers and the schematic with regard to the radio pin numbers (they are not the same).

If you use some other coil then resistance tests would have to be done to try to determine which wires go where (still the un-tuned link might have to be tried the other way around if it doesn't work initially).

I apologize if I am not explaining this very well.

Curtis Eickerman

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 Post subject: Re: Arvin 8576, no reception
PostPosted: Aug Sat 29, 2020 7:44 am 
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3Transistors wrote:
There are two sellers on eBay who have Miller 8813 coils and here is the one with the cheapest price:

https://www.ebay.com/itm/2-PCS-8813-JW- ... Swbb5eFOAH

For less than the cost of those two osc coils, you can buy a complete Chinese six Transistor radio kit, and use the osc coil out of it. If you look at the print, the osc coil connections appear to be the same.
Image

https://www.ebay.com/itm/Superheterodyn ... 0290.m3507

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 Post subject: Re: Arvin 8576, no reception
PostPosted: Sep Tue 01, 2020 9:41 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 543
Location: moreno valley
Thanks for the ideas. The chinese kit one, can't really tell if the pin positions would be in the right position for this radio just as with the Miller one. I do have a few scrap AM and FM radios, I'll take a look at them. Might yank a coil out later and sort of hook it up temporarily just to see if I can get the radio to start up.


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 Post subject: Re: Arvin 8576, no reception
PostPosted: Sep Thu 03, 2020 7:43 pm 
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Joined: Aug Sat 16, 2014 2:19 am
Posts: 1783
Location: Palos Verdes, CA
The Silvertone Model 8204 is similar to the Arvin 8576 and you might find a parts radio one day that may have the components you need:

https://www.radiomuseum.org/r/sears_roe ... _8204.html


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