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 Post subject: Reversed electrolycs from factory??
PostPosted: May Thu 14, 2020 3:27 am 
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Joined: Dec Tue 12, 2017 11:51 pm
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Location: Jackson, NJ
Working on a new project here. I have 4 caps where the + side is going to a common buss strip that is connected to the battery ground through a 1k resistor. I have worked on positive ground radios before, but this is not the case, (or is it????). Please explain!
It also has an unusual battery setup. Label say battery=3v. Takes 2 flashlight cells. Well, the clips do not hit a AA right, & it is too tight a squeeze for two side by side. AAA are too short. Was the another size used back in the early 60's? This is a genetic Japanese made Hi Fi Deluxe. (seems I'm drawn to these things!). I do believe the label is correct stating 3v, because that's the rating on the caps. They certainly didn't leave any room for error! Thanks!
Bill


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 Post subject: Re: Reversed electrolycs from factory??
PostPosted: May Thu 14, 2020 4:09 am 
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Location: Panama City, FL 32401
Maybe you could post a pic of the capacitors you're referring to. AA batteries have in fact increased in length by a fraction of an inch, but enough to be a tight fit in many devices. I've found that myself.
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 Post subject: Re: Reversed electrolycs from factory??
PostPosted: May Thu 14, 2020 4:38 am 
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Joined: Jan Thu 16, 2020 12:29 am
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One reason why AA's got a little longer was many of the early zinc-carbon types did not have a metal disc over the zinc casing at the negative end, it was just the zinc case. When the discs were added, they started to cause trouble with a high resistance connection with oxidation of the zinc. This resulted in motorboating in some transistors radios and not uncommonly in AA operated pocket Hearing Aids. To address this Eveready supplied "hearing aid batteries" with a bare zinc case end, they had a white label with blue writing.

The +ve terminal hardly ever gave any trouble as it was a pressed metal cap over the end of the carbon rod.

So if your AA's are tight (zinc carbon types this refers to) simply remove the metal end disc.It also pays to clean the zinc surface with some 1000 grade paper.


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 Post subject: Re: Reversed electrolycs from factory??
PostPosted: May Thu 14, 2020 3:01 pm 
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Joined: Dec Tue 12, 2017 11:51 pm
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Location: Jackson, NJ
Here's a picture of the caps; positive side going to a central buss. Then goes to negative battery lead. Positive side of battery goes to volume / on-off switch as normal.
A standard AA seems to be too wide because the clip does not reach to the center of the battery, and pops it out of place.


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 Post subject: Re: Reversed electrolycs from factory??
PostPosted: May Thu 14, 2020 3:42 pm 
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ACORNVALVE wrote:
One reason why AA's got a little longer was many of the early zinc-carbon types did not have a metal disc over the zinc casing at the negative end, it was just the zinc case.

Metal disc on neg end was added by late '50s, still batteries didn't "grow".

I suspect the reason they are now longer is for bragging rights, squeeze in another 5-6 mah to beat competition. Of course everyone has now figured out that game, so all are longer.


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 Post subject: Re: Reversed electrolycs from factory??
PostPosted: May Thu 14, 2020 4:26 pm 
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Joined: Dec Tue 12, 2017 11:51 pm
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Location: Jackson, NJ
If this was designed to be a positive ground circuit (I read PNP transistors could be), wouldn't battery positive go to the common + side of the caps?


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