All Forums  GQ Electronics Forums  2.GQ Geiger Muller Counter  GMC-500+ Tube 1 (M4011) shows 0 CPM – need help

Note: You must be registered in order to post a reply.
To register, click here. Registration is FREE!

Screensize: 640 x 480 800 x 600 1024 x 768 1280 x 1024 UserName: Password: Format Mode: Basic  Help  Prompt  Format: Font Andale Mono Arial Arial Black Book Antiqua Century Gothic Comic Sans MS Courier New Georgia Impact Lucida Console Script MT Bold Stencil Tahoma Times New Roman Trebuchet MS Verdana   Size 1 2 3 4 5 6   Color Black Red Yellow Pink Green Orange Purple Blue Beige Brown Teal Navy Maroon LimeGreen Message: * HTML is OFF * Forum Code is ON Smilies [quote][i]Originally posted by bialex[/i] [br]Hi all, I’m having an issue with my GMC-500+. Tube 1 (M4011, marked 2022) constantly shows 0 CPM, while Tube 2 still detects background radiation (~1–2 CPM), so the device is not completely dead. What I’ve tested so far: Tube 1 voltage set to ~42% (~417V), later reset to default (~52%): still 0 CPM Performed factory reset: no change When I manually short/touch the Tube 1 input terminal, the green LED flashes and CPM1 increases, so the counting electronics seem to work So it looks like: counting circuit works Tube 2 works (low sensitivity as expected) but Tube 1 produces no pulses at all My question: Is this more likely a dead M4011 tube, or could it still be a HV supply issue on Tube 1 channel? [/quote]    Insert an Image File Check here to include your profile signature.