CENTRAD 751 (Techniek Radio/TV)

door Thierry Magis , east Belgium, 09.08.2010, 17:14 (5220 dagen geleden) @ Koen

Hello,

What kind of rectifier tube do you want to test ?

For this tubes you have generally two anodes and you have to make two measures!

Example with one EZ81, first test is with the keys (SELECTEURS) combination AACBDDCCCC ; second test with the combination ACCBDDCACC.
Key combination is easy to understand.
A = Anode
B = cathode
C = unused pin
D = heater (of course 2 pins have to be D, except cold cathode tubes)
Key 1 = pin 1 and so on.

So after adjusting heater voltage and plug the tube on, place the keys on the 1st position (given for the tube in the manual) and turn on the instrument. The FONCTION rotating selector will be now used for the different steps.

1st step : "ESSAI FIL" will test the heater. If bad, the neon light on. If it's like that, you can throw the tube...
2nd step : "ESSAI ELECTRODES" (4 positions), will check if no internal short-cut between the tube elements. Note : at this moment, the tube will be heated to test with hot elements. Better to give time to reach normal temperature.
3rd step : "MES" will check if the cathode still gives enough current. The meter has 3 zones : BONNE (tube ok) DOUTEUSE (tube poor) MAUVAISE (dead or very low emission)
4th step : "ISOL CATH" will measure the insulation between cathode and heater. Don't do this test on direct-heating tubes (like 80), it will of course indicate a short-cut ...

You have to do this 2 times, for each key combination ! Turn OFF the instrument when changing key combinations!!

Is this helpful for you ? This is a very quick translation of the manual.

Regards
Thierry