diyAudio

diyAudio (http://www.diyaudio.com/forums/)
-   Tubes / Valves (http://www.diyaudio.com/forums/tubes-valves/)
-   -   B&K 700 problems? (http://www.diyaudio.com/forums/tubes-valves/106350-b-k-700-problems.html)

ThSpeakerDude88 4th August 2007 04:11 AM

B&K 700 problems?
 
I have a B&K 700 that I got from a neighbor who used to be a TV repairman. I have tested a bunch of tubes on it, but I have started to notice that a lot of un-used new tubes that I have (JJ's and sovteks) are testing bad or minimal.

For example: a new un-used JJ 12AT7 tests 60/80
A new un-used JJ 12ax7 tests 20/22
A new un-used Sovtek 12ax7 tests 18/19


For the books, some 1964 sylvania 12ax7A's both tested a matched 30/30 per tube.

Also , some EL84's have been testing a bit low too. I am wondering if the unit is out of calibration? I am using the correct sensativity/socket/heater settings.

This unit has two tubes in it, an 83 rectifier and I don't remember the other one...

Any help would be greatly appreciated.

Cobra2 4th August 2007 09:40 AM

Calibration & schematic here (B&K 700 = 707)
http://tone-lizard.com/B%26K_tube_te...nformation.htm
more manuals here: http://bama.sbc.edu/b&k.htm

The 83 tube can easily be replaced with a ss/diode rectifier.

Arne K

WALTER BURKHARD 4th August 2007 10:52 AM

2 Attachment(s)
my change on a BK707

WALTER BURKHARD 4th August 2007 10:53 AM

2 Attachment(s)
B&K 707

WALTER BURKHARD 4th August 2007 10:55 AM

2 Attachment(s)
from B&k 707 manual , same lke 700

Cobra2 4th August 2007 11:33 AM

2 Attachment(s)
I have used this for SS-replacement (attached).
I think the lower drawing is a better replacement, as the "83" is supposed to have some voltage-drop...
I used 2 x 1,3W zener in paralell (having plenty of the 9,1V.. :cool: )

Arne K

ThSpeakerDude88 6th August 2007 12:47 AM

would any of these things cause any problems though? Do some tubes really come reading THAT low?

Cobra2 6th August 2007 05:05 AM

And what does the chart tell? " Good if it reads 22 or more "
It does not need to be off calibration by much, to get your result...

Arne K

skaffern 14th January 2008 08:32 PM

Kallibrering av B&K 700
 
Hei Arne.
Jeg har nettopp kjpt en B&K 700 og trenger info om hvordan jeg kan kalibrere denne.

Cal Weldon 14th January 2008 08:34 PM

Please use English on these forums. If you wish you may post using both English and your native language but please ensure the English version is accurate.

Thank you.


All times are GMT. The time now is 09:19 AM.


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