26 September 2022

Almost working circuit with 6LO1 CRT

A square little 6LO1 CRT and associated circuit.
A square little 6LO1 CRT and associated circuit.
 

The are a few reasons why I bought this homemade circuit originally meant to display the two ellipses when tuning an RTTY signal:

  • it has a small CRT, probably 6LO1
  • it has a proper transformer with filament and HV
  • it might not work right out-of-the-box 

I was three times right! The CRT lights up and responds to both X-Y inputs but

  • it is out of focus
  • the beam doesn't reach display ends
  • something overheats

At closer inspection I saw that a resistor has suffered some form of heat shock. One resistor is floating and the wiring is close to a nightmare, let alone the routing and crossing of high voltage lines.

I do have the schematic diagram which matches the PCB (oh, BTW, it is double sided but the magazine showed only the bottom side). But schematic and component placement (not shown here) differ with values especially in the CRT bias network.


The schematic diagram: it's a starting point!
The schematic diagram: it's a starting point!

Well, it is not a complex circuit and with some extra parts I should be able to get it running... one day. I should also add a Z-axis control if this is going to become a clock.