Diode replacement suggestions

Eastham

More Class-A than ever!
So I recently bought a Yamaha CR-600, pretty sweet device but it's developed a mains hum in both channels and at first power up you can hear the transformer make a sort of very low humming noise until the protection relay kicks in and I think it's a bad diode in the FBR, The diodes in question are D802 - 805, 10DC-2, 10DC-2R, 10DC-1 and 10DC-1R, these are wierd diodes and I've never seen anything like them before. Any suggestions would be greatly appreciated. I'll also be shotgunning all the electrolytics on the PS board, and I might upgrade the filter caps later down the line but for now they test fine. Thanks!
 
can you post pics ?
general purpose rectifier diodes of the correct rating will most likely be fine .
 
Hi Pete. They're those four 3 pinned black and red things ont the board, but looking at the board that black thing above the fuses looks to be the bridge rectifier to me which is weird because it's not in the service manual.

YT9uuD5.jpg
 
That is D801. It is a 5b-2.

upload_2017-7-19_19-25-46.png

I believe this is where it would be if it were shown.

upload_2017-7-19_19-27-47.png


From the parts list

upload_2017-7-19_19-29-9.png

Your picture shows the manufacturer's (International Rectifier) part number.

upload_2017-7-19_19-31-55.png
 
Thanks, I like music. I think I've fixed the problem, there was a bad joint on the third pin of the 5B-2 so I reflowed all four pins and then I noticed another issue, the bias for the left channel was at 140mV! Yesterday I'd set it too 23mV, as soon as my screwdriver touched the pot it shot back down, I should have noticed with how hot the outputs where. Man did I get lucky the left channel didn't go into thermal runaway. I think the pot's are toast so I got some replacements on the way. Thanks for the help guy's! :beerchug:
 
Sorry to bother you guy's again, but I was wondering if one of you or anyone cold tell me if this bridge rectifier would be an adequate replacement for the 5B-2?

http://uk.rs-online.com/web/p/bridge-rectifiers/6294475/

All the specs seem to match or exceed the originals apart from the max forward voltage, the 5B-2 is rated for 2.5v whereas the replacement I've found is only rated for 1v. Would this be an issue? I only ask because I'm certain the 5B-2 is actually failing. At first I thought that resoldering that joint had fixed my problem, but the hum is still there, just a lot quieter and it was already pretty faint, but I've also noticed the transformer is still resonating and my multimeter is showing shorts between the pins in all directions. If I power it up with a DBT it comes out of protection but the bulb on my DBT shines pretty brightly. Guess that, that rectifier is toast? One of the filter cap's is a little on the low side, 3,800µF compared to the original 4,700µF but I doubt that, that's a big enough difference to cause hum, right? Oh and all the other little rectifiers check out fine and I'll be ordering all the electrolytic's I'll need to recap this Power supply aside from the main filters.

Here's the spec's I've found for the 5B-2 if you need them.

EyOYAGZ.png


Again sorry to be a pain, I'd just like to be sure. I really like this rectifier as it's a similar package as the 5B-2.

Thank's again.
 
Sure, you can even use a bigger one, let's say 10A 600V.

About hum, sometimes they do, you can put some nice 6800uf 50v, since you are there.
 
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Who doesn't love overkill? So I figure Max forward voltage doesn't matter?
If not I'll probably go ahead with this then.
http://uk.rs-online.com/web/p/bridge-rectifiers/6875872/
Thanks.
That's the spirit!!, replace the filter caps too, is not too expensive and it helps.
My sansuis AU-999 I think use that rectifier, and I installed something silly like 25A 800V or something like that :p.
Are the D802 to 805 ok?
Just in case you can order in mouser.co.uk too.
 
That's the spirit!!, replace the filter caps too, is not too expensive and it helps.
My sansuis AU-999 I think use that rectifier, I a put something silly like 25A 800V or something like that :p

Lol, nice. I'll try to cram as many 20,000µF cans in it as I can! So much inrush current that it dim's the whole city! :bigok:
 
you will be ok with 6800uf 50V, don't worry.

This is a nice thread about power switches.
http://www.audiokarma.org/forums/in...orth-5-and-an-hour-or-so-of-your-time.504673/

Just a nice little extra reserve power for those fast paced songs. That's an interesting thread and something I should actually consider, this Yamaha has a wierd and more than likely unobtainium power switch, it's a slider that the flip switch pulls down or pushes up. I was thinking about tapping off the 12v rail and using the power switch to energize a 12v relay that would switch the mains power. But that does seem a lot more compact and simple, thanks for the head's up on that!
 
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