# Aristocraft DC power supply and controller 5450, 5401 DEAD?



## GscaleTed (May 13, 2010)

Hi ALL!
I have this 2 part power supply from Aristo-Craft. The DC power supply works puts out 20 V, dc ( I have a meter). Then you attach the supply to the controller...it doesn't seem to work. It puts out the same 20 VDC, ALL the time. The knob has no effect. When you use the switch that changes direction or stop, that does work, it does stop when you put it in the middle. It does change voltage polarity, or direction when you move the switch. IS IT DEAD? That controll knob has no effect, is there some sort of reset inside?
Many thanks, Ted


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## toddalin (Jan 4, 2008)

My MRC 6200 did the same thing. It was a burned out transistor (shorted) that continually allowed 21 volts to come through regardless of the throttle setting. The forward and reverse still worked. I suspect the same has happened to you. If you are handy with a soldering iron, you may be able to find a replacement and replace it yourself. Otherwise, get hold of AristoCraft for repair.


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## GscaleTed (May 13, 2010)

Hi Toddalin. 
Well I would be handy with a soldering iron. Is it easy to find after I open it up. or will I need a schematic? Just what transister is it? 
THX, Ted


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## George Schreyer (Jan 16, 2009)

Look for a single device, probably a TO-220 package (3 leads, a black epoxy body and a tab with a single screw hole). Hopefully, it will have a more or less standard part number on it and you can find a suitable replacement. A shorted output FET will do just what you describe. Todd is probably correct in his assessment.


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## Dan Pierce (Jan 2, 2008)

I have fixed several of these and it was a broken circuit board. I just added solder braid across the broken etches. 

You do have to scrape off the coating to get the solder to adhere.


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## GscaleTed (May 13, 2010)

Hi Dan.
Thanks for the info. Were did you get the Triangle OR Delta driver to get the 5401 open? Do you know what size it uses?
Many thanks, Ted


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## Dan Pierce (Jan 2, 2008)

I used a screwdriver that just fit and replaced the screws when reassembling with philips.


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## George Schreyer (Jan 16, 2009)

Roomba batteries also use triangular drivers. These are very uncommon, but easy to make from a regular hex key. Simply pick a hex key with the right span between 3 of the points and file the other 3 points off


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## GscaleTed (May 13, 2010)

Hi Dan AND George! 
Thanks for all your help and suggestions! 
I finally opened it up with the correct sized blade screw driver, the first one I used broke, I thought I needed the correct Triangle driver, gave up on finding one of those in the correct size! Anyhow...I tried a stronger blade screw driver, got the screws out. I can tell by how easy they all came out that someone has been in there before! 
I found that one of the screws that holds the heat sink on has snapped off, I don't think that it is a big deal! I couldn't find an obvious crack on the board, so I think that idea is out. I have pix below. So I'de say it's that Transistor that's attached to that giant heat sink! It says " BUZ11 H5 49, with an "H" type insignia", were does one buy a single transistor? There used to be a electronics parts place 30 miles away, now long closed, were can I hunt this Xter down, or an equivalent? 
Many thanks to ALL!!! 

Ted


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## GscaleTed (May 13, 2010)

Hi ALL Again! 
So I did some snooping online! Found out that I have a BUZ11 MOSFET transisiter. There a several on Ebay. How can I tell which is the correct one to buy? 
Many thanks, Ted


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## George Schreyer (Jan 16, 2009)

A quick Google search found the data sheet for a BUZ11 at this link 

http://www.futurlec.com/Transistors/BUZ11.shtml 

This part maps to an NTE2389 replacement part 

http://nte01.nteinc.com/nte/NTExRefSemiProd.nsf/69d5aa3584d015ce85256e780056e56f?CreateDocument 

NTE sells parts through many electronics distributors and Fry's 

http://www.frys.com/search?search_t...y_string=nte2389&submit.x=14&submit.y=5&cat=0 

The part is about $5 ordered on line.


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## George Schreyer (Jan 16, 2009)

before you order the part, remove the old one and turn the controller back on. You should have zero output voltage. This is just to verify that the part you removed is really dead.


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## GscaleTed (May 13, 2010)

Hi again Geaorge! 
Thnaks so very much Geaorge! 
I also find the part at this Florida place. Will it also work? 
http://www.westfloridacomponents.com/blog/?p=219 

Many thanks ALL! 
Ted


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## George Schreyer (Jan 16, 2009)

looks like the same part


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## Manco (Jan 5, 2009)

If it's any consolation, I had the same controller that had the same problem... so looks like a pretty common issue. Looks like you're well on your way to fixing it, but if it doesn't work out, you can send it to Aristocraft for the price of the shipping and a $20 fee and they will fix it. Takes about 3 weeks to get it back.


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