Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

B&K 700 problems?
B&K 700 problems?
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
Thread Tools Search this Thread
Old 14th January 2008, 08:58 PM   #11
Cobra2 is offline Cobra2  Norway
diyAudio Member
Cobra2's Avatar
Join Date: Apr 2002
Location: Stavanger, Norway
B&K 700 problems? B&K 700 problems?


Arne K
Don't believe everything you think...
  Reply With Quote
Old 15th January 2008, 12:44 AM   #12
hailteflon is offline hailteflon  United States
diyAudio Member
Join Date: Sep 2006
I have a 707, much the same as the 700.

I have been going through a tube collection acquired over the years, caddies, etc.

Many new tubes are weak or bad. Repairmen kept the old tubes for some reason. Either they sold them to suckers, tried them in another t.v., or took them back to the distributor for a replacement.

Many tubes are annual re-tube leftovers of industrial equipment maintainence. Again, they kept the old tubes, possibley for warranty verificaton in the event of a dispute.

With experience you can spot the old tubes, but I couldn't years ago. With Sylvania and RCA the color of the chalk changes. Can also match the logo on tube with vintage of box. Many new tubes have bent pins from the factory and also a new tube can have bent pins because someone tried it to test a circuit and then put it back in the box.

Current production tubes can be factory seconds. Sovtek, from what I have gathered, sells crates of unchecked tubes. The duds are probably sold to the unwary. The tolerances of commercial tubes are very sloppy. JAN (military) tubes never check this way, they are always very strong: far into green on the meter. They are screened for quality. I have many Sovteks that are very weak from major distributors. Sovtek evidently leaves the quality control to the buyers.

With power tubes a brown ring around the getter spot means lots of hours.

Calibrate your 700: three adjustments. Check the component values of the tester circuit and replace electrolytics with NEW ones, not NOS. Buy them from a major distributor that has sufficient turnover to have really new caps in stock.

Clean the socket terminals with toothpicks, but watch the wood residue. Dip the toothpick in tarn-X and rotate it in the terminals. You will see when the crud stops coming loose.

Also, worn sockets are a problem. Replacing a socket is easy if you cut the whole terminal off of the old socket and solder the whole thing onto the new socket terminal. Take pictures first.

Also, in case you don't know, the lower test is only an emissions test. Mark
  Reply With Quote
Old 14th March 2009, 04:59 PM   #13
marky mussel is offline marky mussel  United States
diyAudio Member
Join Date: Mar 2009
I recently purchased a BK700 but it doesn't work.
I disassembled it and found the cap on the test meter was not connected (its connect on one side the positive side and the other lead is off .could someone tell me where it connects.
  Reply With Quote


B&K 700 problems?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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
GFA-565 problems ben62670 Solid State 5 14th August 2008 06:36 AM
HK AVR 335 Problems utjay2008 Solid State 0 21st October 2007 02:26 AM
Sub Amp Problems Thanks! crippledchicken Solid State 2 10th January 2007 06:17 PM
JLH problems serosmaness Solid State 11 2nd November 2004 06:17 PM
RFI problems laz Solid State 3 21st February 2004 07:06 AM

New To Site? Need Help?

All times are GMT. The time now is 08:00 AM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio