Replacing Rectifier Disks

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Replacing Rectifier Disks
Posted by gottcent on Tuesday, October 09, 2018 5:32 PM

Does anyone know where I can get instructions for replacing the old rectifier disks in smaller postwar transformers with a new electronic diode? I'm especially interested in instructions for 1033 and LW transformers. I have a new diode but it came without instructions.

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  • From: Austin, TX
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Posted by lionelsoni on Tuesday, October 09, 2018 7:00 PM

Here is a link to a schematic diagram for a 1033:  http://pictures.olsenstoy.com/cd/transfmr/ps1032a.pdf

The label "RECTIFIER" is just above the component symbol for a "crystal rectifier", now commonly called a diode.  It looks like an arrow touching short bar perpendicular to the wire.  Ordinarily the arrow points from the "anode" to the "cathode".  But it is shown backwards here and in all the postwar manuals I have ever checked.

The diode component you have may be marked in various ways.  Sometimes the diode symbol is printed on the side of the diode.  Plastic-cased diodes have a band painted around the cylindrical case at the cathode end.  Generally, if one terminal is marked in some way, it is the cathode.

So put your diode into the circuit with its arrow pointing the other way from the diode in the diagram.

Actually, a postwar whistle will blow no matter which way you put the diode, but modern whistles use the signal polarity to distinguish between whistle and bell.

 

Bob Nelson

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Posted by Michael6268 on Tuesday, October 09, 2018 7:04 PM

This might help.  Its procedZW but basically the same procedure...

www.tranz4mr.com/ZW_Whistle_Diodes.html

 

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Posted by northernpike on Tuesday, October 09, 2018 10:00 PM

Great topic.

My disks need replacing also.  What are the pros and cons of repro disks and the new diodes?  Run postwar conventional on kw, rw, sw and 1033.

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Posted by rrswede on Tuesday, October 09, 2018 10:06 PM

Here is a tutorial from OGR.

https://ogrforum.ogaugerr.com/topic/diode-conversion-for-lionel-1033

swede

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Posted by lionelsoni on Wednesday, October 10, 2018 11:46 AM

Pro:  The silicon diode is more robust than the copper-oxide.

Con:  It's not a big deal; but an ordinary silicon diode has a higher forward voltage than the original copper-oxide and therefore is a slightly less efficient rectifier.  A Schottky diode is a closer match.

Bob Nelson

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Posted by northernpike on Wednesday, October 10, 2018 7:18 PM

Bob

Thanks.  Very interesting.  Might have to try a diode on one of my transformers to compare.

Tom

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    January, 2006
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Posted by gottcent on Thursday, October 11, 2018 8:53 AM

Thanks, guys. Those tutorials look especially helpful. I'll give it a try.

John

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