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 Post subject: Ferrite ring memory
PostPosted: Feb Mon 26, 2018 8:25 pm 
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Joined: Feb Fri 16, 2018 11:01 pm
Posts: 13
Location: Maryville, MO
Working on an old jukebox. I is mostly tube amp and mechanical record selection with the exception of the record select memory.
It uses ferrrite rings with 2 windings for memory. Best I can figure, it magnetizes in one direction (vertical) for a "1" and the other direction (horizontal) for a "0".

I think the magnetizing pulse voltage is missing but my vintage o'socpe crapped out and I haven't replaced it yet. I can't capture the pulse on a DMM but it may simply not be pulsing.

Anyone have any experience?


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 Post subject: Re: Ferrite ring memory
PostPosted: Feb Mon 26, 2018 8:32 pm 
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Joined: Jul Mon 26, 2010 8:30 pm
Posts: 23374
Location: Annapolis, MD
Fix or replace scope.

Seriously, it's pretty much impossible to trouble-shoot pulsed circuits without a scope.

Can you post the relevant section of the schematic?....or better, a link to the whole thing.

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 Post subject: Re: Ferrite ring memory
PostPosted: Feb Mon 26, 2018 8:59 pm 
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Joined: Jan Fri 06, 2012 8:47 pm
Posts: 6422
For what it's worth here is a description of the Tormat type of memory used by Seeburg for their jukeboxes https://www.flippers.com/Seeburg-tormat.html . Interestingly Joernone on Youtube (badrestorer around here) is currently working on a Seeburg and has not yet achieved having it select records just yet.

Curtis Eickerman

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 Post subject: Re: Ferrite ring memory
PostPosted: Feb Wed 28, 2018 1:53 am 
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Joined: Jun Sun 15, 2014 11:04 pm
Posts: 928
Location: Coos Bay, Oregon
I do have experience with the tormat type memory, however, the circuitry is a bit complex and difficult to diagnose by message, especially since the model is not known. If it is a Seeburg, they were pretty good about providing comprehensive data on their core memories. Get your hands on a complete repair manual. It has all kinds of diagrams, troubleshooting charts, and adjustment procedures. In addition, I strongly recommend replacing all capacitors in the selection unit, and checking all tubes and voltages on them. If yours is a hybrid (tube and solid-state), you'll need testers for both kinds of elements. Cheers, Russie Ofria


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 Post subject: Re: Ferrite ring memory
PostPosted: Feb Wed 28, 2018 7:44 pm 
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Joined: Mar Tue 03, 2009 11:12 pm
Posts: 1444
Location: Hutchinson KS
If the thing uses tubes the last time I worked on one of those about 30 years ago, replacing several high ohm resistors repaired the unit for me.


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