Number of diodes

#1 Fri, 20 Mar 2015 - 04:19 68kMLA

What is number or name of this diodes? This is mac classic analog board.

if4mrk.jpg.6bfb50ddce429358483e3317f831963c.jpg

#2 Fri, 20 Mar 2015 - 05:44 68kMLA

most of the the issue with this A/B are these caps.

https://68kmla.org/forums/index.php?/topic/22903-tempermental-macintosh-classic/

/monthly_06_2014/post-2052-0-06463800-1403200924.jpg">View attachment 3233

#3 Fri, 20 Mar 2015 - 08:00 68kMLA

All caps are replaced. This two diodes has fail but i can't read any text on those because it is unreadable.

#4 Fri, 20 Mar 2015 - 09:03 68kMLA

if i had to guess they look like this

http://www.radioshack.com/3-amp-diodes/2761143.html#start=5&sz=12

and that leads me to realize, does this POS only use a half wave rectifier!?

no wonder why the smoothing caps take such abuse!!!!

I wonder how hard it would be to retrofit a bridge rectifier for that spot??

#5 Fri, 20 Mar 2015 - 15:31 68kMLA

They are high frequency shotky rectifier diodes, fast recovery time. Bridge rectification isnt needed at these frequencies.

#6 Fri, 20 Mar 2015 - 18:52 68kMLA

Mike you got a minute can you post a link to what part you think they are?

#7 Fri, 20 Mar 2015 - 18:53 68kMLA

http://www.radioshack.com/nte-nte506-r-si-hi-fast-switching-silicon-rectifier-diode/55051283.html#q=rectifier+diodes&didyoumean=1&start=2

this?

#8 Fri, 20 Mar 2015 - 23:10 68kMLA

No, no NTE parts. Ill spec it, hang on.

#9 Fri, 20 Mar 2015 - 23:20 68kMLA

BTW these arnt bad unless they read shorted.

But regardless, here you go:

http://www.digikey.com/product-detail/en/SB550-E3%2F54/SB550-E3%2F54GICT-ND/868999

#10 Sat, 21 Mar 2015 - 05:31 68kMLA

thanks bud!, I'm sure the op thanks you too!

#11 Sat, 21 Mar 2015 - 08:17 68kMLA

thanks. now i can repair my mac!