Tube stuff

Here's a nice diagram and cool explanation of signal flow through a common tube circuit.

http://www.el34world.com/charts/currentflow.htm

Video on biasing a Sound City L-B 50. By connecting one end of your multimeter to the centre tap of the output transformer and the other to pin 3 of the output tube. Read the current here. Should be around 42mA.

http://www.youtube.com/watch?v=PYuFsZhFIe8

Great site and forum for vintage gear

http://vintageamps.com/

Simple circuit to switch between tube rectifier and solid state rectifier in a tube amp.

Tubes 101

A tube amp works by letting 2 different types of voltage pass in 2 different directions, while not letting the 2 pass the same way together. The guitar signal which is a low AC voltage goes from the input jack toward the speaker output (getting bigger along the way) while the high DC voltage that powers the tubes runs back in the reverse direction often along the same connection points that serve as stage inputs for the AC signal.

Signal runs straight to pin 2 of the input tube (12AX7).
Pin 2 is known as  the Grid.
Pin 1 is the output which is also known as the Plate.
The flow of electrons from grid to plate increases gain.
Pin 3 is the cathode. This determines the operating level.

Parts

Came across this link while searching for a 7 pin headphone volume pot for a Vestax DJ Mixer.
Might come in handy

http://www.potentiometers.com/

http://www.potentiometers.com/SeriesP140.cfm

http://www.ebay.ie/itm/10-Potentiometer-pot-10kAx2-stereo-audio-log-7-pins-CD-mixer-Zeck-/330918401757?pt=LH_DefaultDomain_186&hash=item4d0c4616dd

NAD C325BEE Repair

This is a picture of a NAD C325BEE stereo amplifier that came in for repair. The 

Amplifier Fan Control

Automatic cooler fan for ampifiers

http://www.circuitstoday.com/automatic-cooler-fan-for-amplifiers

Free Wheeling Diode

http://www.control.com/1026147908/index_html

Another Fan control circuit

http://sound.westhost.com/project42.htm

Comparator video tutorial

http://www.youtube.com/watch?v=y0Q0ERSP24A

Electronics forums

Here are some interesting forums about music and electronics. Lots of good info here.

http://music-electronics-forum.com/activity.php?s=83f284281a5e9faac798355a729c6aa1

http://www.electronicspoint.com/

http://www.audiokarma.org/

www.diyaudio.com/‎

www.diyrecordingequipment.com/‎

Safety first!

Here is an isolation transformer. Been meaning to get one of these for the workshop.

http://radionics.rs-online.com/web/p/safety-site-transformers/4368798/

http://en.wikipedia.org/wiki/Isolation_transformer

Hello

This is my first time setting up a blog. I'm gonna do it as a sort of repair journal detailing the repairs I carry out on sound equipment. To get it started and content on I will add interesting articles and videos I come across too.