Replacement part for 50yo bridge rectifier? - diyAudio
Go Back   Home > Forums > Design & Build > Parts

Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 28th December 2010, 05:45 PM   #1
Stabby is offline Stabby  Belgium
diyAudio Member
 
Join Date: Sep 2010
Default Replacement part for 50yo bridge rectifier?

I'm working on the pre-amp of a 50-year-old electric piano and will probably have to replace the bridge rectifier. It's pictured in this photo next to the transformer:

http://i.imgur.com/rH3KW.jpg

I have no idea what to look for though, since I can't interpret the information printed on the rectifier:

B250 075
KC068 22/8

Also, the rectifier is connected to two 350/395V capacitors.

Could anyone help me out?
  Reply With Quote
Old 28th December 2010, 06:16 PM   #2
nac134 is offline nac134  Canada
diyAudio Member
 
Join Date: Sep 2008
Google B250 rectifier. Theyre available.
  Reply With Quote
Old 28th December 2010, 06:20 PM   #3
Mooly is online now Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Hard to make out...
I assume it's silicon and not selenium... did selenium work at those voltages ?

You need to measure the AC voltage across the bridge and the DC across any reservoir cap. Does it follow the Vdc = 1.414 times Vac formula or not. Selenium has a larger volt drop. Just with you saying it was 50 years old.

Silicon... loads of choice but measure the voltages first and see what it runs at.
__________________
-------------------------------------------------------
Installing and using LTspice. From beginner to advanced.
  Reply With Quote
Old 28th December 2010, 06:37 PM   #4
diyAudio Member
 
indianajo's Avatar
 
Join Date: Jan 2010
Location: Jeffersonville, Indiana USA
You can replace selenium rectifiers with silicon, but sometimes you have to add series resistance at the appropriate wattage and voltage rating to keep the load voltage from getting too high. Note 1/4 W resistors are no longer rated at 400V because they are too short. 1 W resistors are usually rated above 400 V but check your supplier tables. Phenolic headers are handy for mounting discrete components to chassis at these high voltages, attaching to the metal with machine screws. tubesandmore.com sells them, calling them "terminal strips". I can't find headers at mouser, farnell, any of the usual international sources. With phenolic headers, you can also make a bridge out of 4 each 1n4007 etc. the way most vendors did in that era.
__________________
Dynakit ST70, ST120, PAS2,Hammond H182(2 ea),H112,A100,10-82TC,Peavey CS800S,1.3K, SP2-XT's, T-300 HF Proj's, Steinway console, Herald RA88a mixer, Wurlitzer 4500, 4300

Last edited by indianajo; 28th December 2010 at 06:42 PM.
  Reply With Quote
Old 30th December 2010, 08:19 AM   #5
RJM1 is offline RJM1  United States
diyAudio Member
 
Join Date: Jan 2010
Location: Titusville, Fl.
Are you sure it's not a B250 C75 bridge? If it is there is some information on replacing the B250 C75 selenium rectifer about two thirds down the page on this site:-

1958-1959 Grundig "2066 PX" AM/FM/SW Radio Restoration

You could use a small silicon bridge rectifier (about 1A 1000V) or four 1N4007 diodes in bridge formation, and a 100 ohm 10W resistor in series with the output to compensate for the voltage drop.

Mooly, 30KV Selenium diodes.
http://www.nteinc.com/specs/500to599/pdf/nte504.pdf
Attached Images
File Type: jpg B250 C75.jpg (34.4 KB, 53 views)

Last edited by RJM1; 30th December 2010 at 08:41 AM.
  Reply With Quote
Old 30th December 2010, 10:31 AM   #6
Mooly is online now Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Quote:
Originally Posted by RJM1 View Post
Thank you
__________________
-------------------------------------------------------
Installing and using LTspice. From beginner to advanced.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
SCHOTTKY RECTIFIER FYP2010DN Y2010DN 20A/100V replacement/equivalent part help steptoe1111 Parts 10 24th December 2010 07:59 AM
Bridge rectifier vs Full wave rectifier hilbert_mostert Tubes / Valves 4 28th April 2009 08:26 PM
Anybody heard about Tarzian Silicon Rectifier for Tube Rectifier Replacement? zxx123 Tubes / Valves 4 21st February 2005 04:02 AM
Integrated Rectifier Bridge VS Rectifier Diodes Sci Chip Amps 11 16th July 2004 02:43 PM
Bridge Rectifier thylantyr Solid State 2 21st August 2003 09:11 PM


New To Site? Need Help?

All times are GMT. The time now is 06:25 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2