From: Jeff@invalid.invalid   
      
   On 03/09/2025 14:20, Cursitor Doom wrote:   
   > Gentlemen,   
   >   
   > I have an early AVO valve tester (twin panel type, Mk1 or Mk2) which   
   > I'm trying to get fully working. Anyway, I have a problem with it   
   > which I've never encountered before. I set the panels up to test a   
   > valve, set the anode and heater voltages etc, the valves are glowing   
   > just like they should, but when I apply the prods of a DVM across the   
   > heater pins to check if they're correct WRT the switch setting, that   
   > tiny extra load completely collapses the supply to the heaters! The   
   > meter reads 0V (or close enough) and the heater glow dims to nothing.   
   > Any idea WTF's going on here?   
      
   I'm a bit confused here. You say that you set up the panels to test *a*   
   valve, but then you refer to the *valves* glowing like they should. Did   
   you test more than one valve, and did these use the same or different   
   sockets - eg only octal, or octal and noval? I'm also a bit surprised   
   that there is space to put a DVM probe on a pin when the valve is in its   
   socket, unless the valve is partially loose. That doesn't explain what   
   you found, but perhaps the socket is cracked and the pin connector is   
   shorting out somehow. What happens if you put a resistor (which would   
   draw a similar current to the valve filament) in the socket instead of   
   the valve, and monitor the voltage across that with the DVM?   
      
   I assume, by the way, you've seen the large number of threads here:   
      
   Is this of any use   
      
      
   --   
   Jeff   
      
   --- SoupGate-Win32 v1.05   
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