© COPYRIGHT NOTICE All Rights Reserved

Universal Card #1 for the L3-3 tube tester
(Last updated: 26-Nov-2017 14:02 )

 

Note, there was never an instruction for "How to make your own cards". Indeed it is not recommend try to quickly make your own cards, this can and will go wrong.

The purpose of the universal card is:

1) Analyse existing cards, by get the tube to work with a specific card. After that remove the card plugs, and lay the universal card on top of the card you want to analyze. Put back in the plugs, and now you can see how the card is programmed. As the original card is still underneath, you can make no mistakes.

2) Make small variations on known to be good cards. We just mention the option here, but generally this not a good thing to do. We understand it is tempting, but you have to be aware there is no protection in the plug system, against wrong programming. Many plugs should not be removed with a working tube inserted, and some plugs may only be changed in groups of two. Apart from that, you can do it wrong, and cause a short when you play with socket connections and setup up of the internal high voltages.

The L3-3 is programmable for a real Single Ended amplifier inside, so the tube is tested in a real circuit. That is the auto bias test for amplifier tubes, and also the rectifier test works by programming a real power supply and put a load on it. These are those massive green resistors at the back, you can look inside through the holes, and some of them are used as auto bias resistors too. For the rectifier circuit, you can change the input voltage, apply one or more filter capacitors, and change the load. Programming mistakes can damage each of these components inside. The transformer is 500 Watt, and can burn the cable tree or itself in just seconds.


© COPYRIGHT NOTICE All Rights Reserved