SOME UNOFFICAL TEST POINTS AT THE AVO MK4 TUBE TESTER

DISCLAIMER. NO GUARANTEE ON THIS DATA. USE IS ON YOUR OWN RISK.

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The Mk4 tester is a result of 25 years of development. So how good is it, it is hard to say.

 

Many very interesting data points are on this panel, you can connect a scope or a Voltmeter to it, and look inside your Mk4 without opening it, and no risk to damage anything. Even more ideal, some circuit ground would be on here (This is not chassis ground) . It is not now, but I will add this later.

IF YOU HAVE SOME MORE KNOWLEDGE ABOUT HOW TO USE THESE TESTPOINTS,
PLEASE LET ME KNOW!

TESTPOINT (TP)  
1 Center Tap of Screen Selector Switch
2 Center Tap of Anode Selector Switch
3 "COARSE" Pot meter. Center Connection
4 = 11 Return point of total tube current. (Anode + Screen). Connected via Relay to Zero Volt point of HV supply.
5 =15
6 Grid (g1) transformer Top wire from schematic. (Red wire to transformer)
7 Screen half wave rectified voltage
8 Anode half wave rectified voltage
9  

10

BACKING OFF Voltage, negative. (=Anode of backing off diode, MR1)
12 "Set Vg" Pot Meter Center. Connection to diode
13 Heater Link (Offical Testpoint)
14 Heater Link (Offical Testpoint)

15

Vg Link 15 (Offical Testpoint)

16

Vg Link 16 (Offical Testpoint)
17 "Set Vg" Pot Meter Center. Connection to R43
18 "Set ~" Pot Meter. Connection to transformer.
   

DISCLAIMER. NO GUARANTEE ON THIS DATA. USE IS ON YOUR OWN RISK.