# Diodes for Aristocraft 10 amp power supply



## Traincrazychapple

I have an 1997 version Aristocraft Ultima 10 amp power supply. The black one that that resembles a battery charger. The diodes are shot. Has anyone replaced their diodes? If so could you lead me to the supplier? I've tried Scott Polk, but he hasn't replied. There must be suitable replacements but I need a part number or description. anyone please who are experienced with power supplies.
Thanks a bunch.
Dick


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## gunrunnerjohn

Why not just go to a place like Digikey or Mouser and order suitable diodes.


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## Traincrazychapple

*diodes*

Thank you, those are excellent places to buy them. More specifically though, I am looking for the diodes set that was originally used in the Ultima. These were American made. The space is rather tight to fit the diodes on to the heat sink in the unit. If I go for a different shaped set and modify the space available somehow, that'd be okay. I am also unsure what values the diodes should have.

In other words, if you had one of these power supplies sitting in front of you needing diode replacement, what would you put in there?

Thanks again for anyone's help.

I think once I get this repaired, it will be time to sell these old power supplies and pick up a couple good Mean Well switching power supplies. I'm looking at the 350w 24v dc 14.6 amp output variety.
Thanks again.
Dick


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## gunrunnerjohn

Well, since I don't have one of these sitting in front of me, I can't really comment on the specifics of the diodes. 

Perhaps if you supplied a part number off one of the diodes and perhaps a picture of how they're used in the unit, we could be of more help.


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## Traincrazychapple

Thanks for getting back so quickly. There is no part number on it but I will try to post a picture. I have two of these units, one good, one bad, I will try to post a picture of both.


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## gnm109

Hello, 

First Post here. I have all G Scale now. My layout is strictly analog with blocks. I built my own dual 5 amp, 25 V power pack and also a 9 V power supply for my home-made switch machines, all of which use diodes for reversal with two wires. 

10 amp 1,000 VDC diodes are a common value and are very inexpensive. I have them all over my layout. Some of them have been in place for more than 25 years. 

Here's a good source. Good old Amazon. Also, any good electronics store should have them. If you could post a picture, we could tell the package type. 


http://www.amazon.com/s/?ie=UTF8&ke...vptwo=&hvqmt=b&hvdev=c&ref=pd_sl_2zmhdm14ja_b

Hope this helps.


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## Traincrazychapple

Howdy gnm:
Thanks for the input, I appreciate the help. 
I just cannot seem to get pixs posted no matter what.
Description of this unit: A piece of plastic (1.75" long by 3/8" by 1/4" on the sides) has a diode embedded in each end. A flat surface of each diode is all that is exposed. The flat surfaces make contact with the heat shield when the plastic piece is riveted to the heat sink. Then protruding out of each end of the plastic piece is a flat blade type connector to connect the transformer wires to. The flat blades being the other end of the diodes. So they resemble bolt type diodes but without the threaded bolt part.

From what I understand, these are not very good to begin with and are really too weak. Doubtful too is finding replacements. I am going to have to go with much heavier duty diodes and find a way to fit them inside the case.
Dick


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## gunrunnerjohn

I'd find a way to get a picture, I'm having a hard time visualizing what you have there.


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## Traincrazychapple

Hi John:
If I had you email address somehow, I'd sure be glad to email you pictures. I can send them via my gmail account. I've never had any luck sending via centurylink.
Dick


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## gunrunnerjohn

Why not simply post them here, it's a simple process?

How to post pictures


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## Traincrazychapple

Well John thank you very much for the link.

Man I have to admit if I can't make it work, I probably have diodes in my brain that are burned out too. I managed to put hundreds of pixs on LSOL over the years until they closed. Of course each time I did I'd find I would have to relearn the steps again. Grrrr! on my memory.

Later this afternoon I can work on it, I want to take more pixs as well detailing the inside of the ULtima and ultimately....this will be a good resource for others too to look at.

Thanks for hanging in there with me on this.
Dick


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## Traincrazychapple

OOOOps left out the word Brain in my message. LOL


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## gunrunnerjohn

It magically appeared, must be our grammar checker spotted it.


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## Traincrazychapple

*Ultima 10 amp diodes*

Still trying to load pictures.
John I am using method #1 which I am familiar with.
After the pictures upload , I get an administrator note that says "Invalid Post Specified".

Not sure what I am missing.
Dick


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## gunrunnerjohn

Are you sure they're not too big? That's a common issue. Try to make them no more than 1280 wide and see if that works.


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## Traincrazychapple

The pictures are all around 770k, lowest setting on my camera was used to insure typical pictures for uploading such as for ebay.

They seem to upload okay but after they upload to the model train forum site, the administrator note will say "Invalid post specified".

I am just using an "go advanced" reply, not sure what I may be leaving out or putting something in a field incorrectly.
The low resolution I would think is okay, I thought the instructions mentioned that this site will automatically reduce the sizes automatically most of the time??


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## gunrunnerjohn

I think they're too high a resolution, try using a graphics application to reduce the resolution.

IrfanView is a great graphics application and it's 100% free.


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## Traincrazychapple

*Ultima 10amp diodes*

Hope this works. Picture show location of diodes/heat sink and the yellow wires connecto the diodes and the red wire to the heat sink.


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## Traincrazychapple

*10 amp Ultima diodes*









Another photo. The diodes as you can see are encased in each end with the flat male blade connector sticking out. One diode at the top, one at the bottom. 
This set is okay by the way. Where the diodes are on the bad set, the plastic melted inwards, or sunk into the diodes spaces.


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## Traincrazychapple

*10amp Ultima*

Top view.


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## gunrunnerjohn

Where is the plate with the diodes in the top view? Is that not in the picture?

Those don't look like any diodes I've ever seen, and I find it curious that there is no designation of the anode or the cathode? They MUST be connected in the correct orientation, so if they are diodes, there should be a marking.

Can you show where the heatsink that the "diodes" are mounted on sits in the complete unit?


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## Traincrazychapple

Hi John:
We're making progress...got the pictures on here. Your response was very similar to mine when I tried to find replacements. Couldn't find anything close to looking like these.
The 1st picture IS the plate(heat sink) with the diodes John. The male flat blades you see sticking out are the positive anodes of the little round diodes encased in each end of the plastic piece. The negative sides are flat and bare and just rest against the heat sink that the plastic piece is riveted to. That is how they kept pressure against the heat sink is with just one rivet and that cheap piece of plastic. Pretty darn poor. Then there is a clear goop(like the heat sink grease that was mentioned to use) that was applied between the diodes and the heat sink.
If one could take the diodes out of the plastic case they are in, they would look just like the bolt style diode but with the bolt sliced off and pressed against the heat sink instead of being bolted on to the heat sink. And the blades(anodes) are bent over to one side rather than left sticking straight up as the blade(anode) on the bolt on diode is. Look carefully at the plastic piece again and see the raised flat line on each end that goes across the middle above each diode. That line is where one would normally see the anodes sticking up through the plastic.
So all in all, rather than just take two diodes and bolt them on the heat sink and be done with it, this outfit chose to shove two poor little defenseless diodes in that stupid piece of plastic and put one cheap rivet through it to hold the diodes against the heat sink.
I have to say, it lasted 27 years anyway.

As to where this heat sink is positioned. Notice that I am holding the heat sink/diodes in the 1st picture. The unit is position exactly how it goes in the case, just by lowering it down in. It is directly above where it mounts in the case. Notice the plastic buffers in the heat sink. The heat sink is simply bolted to the back of the case and the buffers keep it away from the back of the case. The two yellow wires from the transformer connect to the diodes. The center black wire goes to the circuit board and the red wire from the circuit board connects to blade riveted on the heat sink.

I will probably never find replacements like these. So I will have to use 2 bolt ons and make them work in the space that's available.

By the way, on either Greg Elmassium's site or George Schreyer's site is a schematic of these Ultima 10amp power supplies.
PS after I get done with this, as soon as I save up enough $$$, I'm replacing these old Ultimas with two Mean Well 24v dc 14.6amp units and install two inline fuses for added protection.
Dick


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## Traincrazychapple

I have had a few say go to the auto parts store and look at the alternator diodes. I haven't done that.


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## Traincrazychapple

Two corrections to my reply.
One....Greg's last name is spelled Elmassian.
Two....my Ultimas are 1997 models, so they lasted 17 years, not 27 years.


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## gunrunnerjohn

I'd just check out Digikey and buy some appropriate diodes. From the look of the insides, I'm sure you can orient them on the heatsink so they fit into the case. I'd probably buy some 30-40 amp diodes to give myself a margin.


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## Traincrazychapple

agreed. Thanks John.
Dick


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## Traincrazychapple

Good afternoon John. 
Railroad is up and running again. Got the diodes, installed them, and presto. Much easier fix than I anticipated. There was enough space. Just drilled two holes in the heat sink for the diodes, add a extra spacer to keep the diodes from touching the back of the metal cabinet, even the connetors worked nicely without mods.
YAHOO!!!!
Dick


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## gunrunnerjohn

Glad to hear it went well. I figured there should be a fairly easy replacement for those.


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