# ZW rectifier disc replacement



## ftauss (Sep 18, 2012)

Guy on ebay has 40 and 16 amp diodes to replace the discs. Looks like a pretty easy upgrade. Both list as being 1000 volts, the 40 says it has a 800 amp maximum surge. 

They are $16 and $10 respectively for a pair. Any opinions? I know Gunrunner is big on this upgrade. It's a simple bolt on replacement. Figure while I have it open anyway...

Also - any thoughts on replacing the wiring? I have to desolder a few anyway to completely remove the base to clean it, it's disgusting, and I want to clean as much of the internals as possible, lots of dust in there, The contact spring insulators are very foul and I don't see any on ebay or at Olsen's. Figure everything needs a good wipe down maybe a little electrical lubricant when reassembled.


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## gunrunnerjohn (Nov 10, 2010)

I doubt you need anything more than the 16 amp diodes, the others are overkill for the job. I've never replaced any wiring that didn't need it, if the insulation is intact, I just leave it. Nobody be me will ever see it.


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## BigAl56 (Dec 14, 2011)

You mean these? http://www.ebay.com/itm/2-REPAIR-STATION-40-AMP-diodes-for-Lionel-ZW-or-VW-Transformers-W-INSTRUCTIONS-/350891916676?pt=Model_RR_Trains&hash=item51b2c9bd84

Yep that's kind of what I use although I prefer a 1N1184R stud mount rectifier because it has a slightly wider flange. http://www.digikey.com/product-detail/en/VS-1N1184RA/1N1184RA-ND/81183

Either way these are the best type of parts to replace the old style rectifier disks with. Yes they are overkill but they fit cleanly into the mounting hole and will withstand a lot of abuse.


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## Don Trinko (Oct 23, 2012)

I used a 5 amp diode in a KW and it is still working fine. To high a rating could be a problem in the physical size of the diode not fitting. All IMO; Don


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## ftauss (Sep 18, 2012)

areizman said:


> You mean these? http://www.ebay.com/itm/2-REPAIR-STATION-40-AMP-diodes-for-Lionel-ZW-or-VW-Transformers-W-INSTRUCTIONS-/350891916676?pt=Model_RR_Trains&hash=item51b2c9bd84
> 
> Yep that's kind of what I use although I prefer a 1N1184R stud mount rectifier because it has a slightly wider flange. http://www.digikey.com/product-detail/en/VS-1N1184RA/1N1184RA-ND/81183
> 
> Either way these are the best type of parts to replace the old style rectifier disks with. Yes they are overkill but they fit cleanly into the mounting hole and will withstand a lot of abuse.


Indeed, exactly what I referred to. Placed the order last night along with a few other goodies from him to fix my ZW.


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## ftauss (Sep 18, 2012)

Don Trinko said:


> I used a 5 amp diode in a KW and it is still working fine. To high a rating could be a problem in the physical size of the diode not fitting. All IMO; Don


Same guy had much smaller ones which was just a small cylinder with a couple of legs on for the smaller ones. I grabbed one for my 1033.


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## Don Trinko (Oct 23, 2012)

As far as I know the current for thewhistle is the same no mattervwhat transformer you use . So why would you need a big diode?
I do understand that there is nothing wrong with using the bigger diodes. Don


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## ftauss (Sep 18, 2012)

Don Trinko said:


> As far as I know the current for thewhistle is the same no mattervwhat transformer you use . So why would you need a big diode?
> I do understand that there is nothing wrong with using the bigger diodes. Don


I have no idea. I only recently have become more interested in electricity and much of it still befuddles me. Hence, I ask questions.

On the plus side it is a simple to install.


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## servoguy (Jul 10, 2010)

I use a 5 amp diode and have installed diodes in several KW transformers. The diode doesn't carry any current until the whistle is operated. In the first position of the whistle control, all the current to the loco goes through the diode. However, this is only for a short time. In the second position of the whistle controller, the diode is shunted by a low value resistor, so the current through the diode is reduced considerably. I buy the diodes for about $0.50 at a surplus store here in Orlando.


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## servoguy (Jul 10, 2010)

You can buy 4 diodes from Radio Shack for $2.99. 

http://www.radioshack.com/product/index.jsp?productId=2062591


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## gunrunnerjohn (Nov 10, 2010)

The 40A diodes are way over what you need. I prefer being on the safe side, but the 16A ones mentioned would be more than adequate for the task in any PW transformer.


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## ftauss (Sep 18, 2012)

gunrunnerjohn said:


> The 40A diodes are way over what you need. I prefer being on the safe side, but the 16A ones mentioned would be more than adequate for the task in any PW transformer.


Those are the ones I bought.


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## carinofranco (Aug 1, 2012)

servoguy said:


> You can buy 4 diodes from Radio Shack for $2.99.
> 
> http://www.radioshack.com/product/index.jsp?productId=2062591


Nice! I found a 10 pack for $3.26 with free shipping on Amazon.


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## BigAl56 (Dec 14, 2011)

There is nothing wrong with using a normal diode. Basically there are two reasons I recommend a stud-mount rectifier like the 1N1184R


They fit cleanly into the mounting hole of the existing rectifier disc and act and look like a factory modification.

The mount acts as a heat sink to protect the rectifier in the event someone is blowing the whistle continuously.
Yes, you can 'rig up' a conventional diode and it will work fine but it will look and act like you rigged something up. Why do that when you can cleanly drop in a factory-like replacement?


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## servoguy (Jul 10, 2010)

I try to minimize the money I spend on stuff that is not trains or accessories. That is why I use a 50 cent diode. Also, I am an electrical engineer with 50 years of experience so my experience says a 5 amp diode will work just fine. It is easy enough to install and doesn't need a heat sink. And if it should blow out due to some very unusual situation, it is a cheap fuse.


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## carinofranco (Aug 1, 2012)

I have done both kinds of diode replacement-stud mounted and plain barrel diode. I would use a stud type in a ZW or KW where there is ample room inside the case. For smaller transformers I prefer the barrel type just because the space is tight.


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