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Subject: 
Re: RCX 2.0 circuit board changes
Newsgroups: 
lugnet.robotics
Date: 
Sat, 30 Aug 2003 20:01:54 GMT
Viewed: 
805 times
  
In lugnet.robotics, Mike Thorn wrote:
After reviewing some pictures of the RCX 2.0's circuit board today, I
noticed that they are quite different. Can anybody tell me the reason why?
What changed and how does it affect the RCX?

I'm looking for that infamous diode that so often blows when someone tries
to build their own power supply. The boards are so different, though, that
I'm not even sure if it's there anymore. I need some better pictures before
I can draw a conclusion, though - the ones I have are small and rather fuzzy.

~Mike

Hello Mike,

Here is a photograph (actually a scan) of all three versions (1.0, 1.5 and 2.0)
of RCX: http://www.brickshelf.com/cgi-bin/gallery.cgi?f=38746

I had a look at a few RCX 2.0 printed circuit boards, and at first sight they
are identical. 1.0 contained the rectifier and regulator for external power
supply, this was suppressed in 1.5. The other difference between 1.0, 1.5 and
2.0 comes from the suppression of diodes around Melexis motor drivers, there was
a lot in 1.0, less in 1.5 and even less in 2.0. I guess (not sure, I haven't
analyzed the circuit precisely) that these were protection diodes that proved
unuseful.

And the part that will blow for sure if you goof with power supply is the small
surface mount fuse (rated 1.5A) that protects the board. It can be seen here
http://www.philohome.com/motors/rcx1_5-top.jpg as a small transparent part in
the lower right corner. Note that on the 2.0 PCB
(http://www.brickshelf.com/cgi-bin/gallery.cgi?i=362264), I used a tiny wire to
temporarily replacing the fuse, I was in short supply ;o)

Cheers,

Philo
www.philohome.com



Message is in Reply To:
  RCX 2.0 circuit board changes
 
After reviewing some pictures of the RCX 2.0's circuit board today, I noticed that they are quite different. Can anybody tell me the reason why? What changed and how does it affect the RCX? I'm looking for that infamous diode that so often blows (...) (21 years ago, 30-Aug-03, to lugnet.robotics)

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