Ok, I was silently following this, but got triggered by this
Hi,
as the last info on this:
It is possible to change the LDRs on those two plastic tubes. AFAIK, the type should be NSL-6110.
Regards
Philipp
NSL-6110 looks wrong for the function. its voltage rating is only 100V; where by specification bias voltage should get as high as 3500V. If Cameca is encapsulating these photoresistors in these tubes, then it is no surprise that they burn out eventually and needs periodic replacement. Or they should at least warn users to not experiment with setting Igun anything below 80µA, and clearly state the derate value for higher HV voltage, as increasing HV voltage also increases bias voltage. As two LDRs are used in series, the bias within rating range will be 200V (100V x2) . That looks reasonable bias voltage for 15kV HV 80uA beam... but 25kV, 30kV, and >30kV where bias for 80uA will need to go into thousands of Volts, I have serious doubts if this NSL-6110 would not breakdown. Even working at 20kV would probably go easily over 200V.
Another question is replacing it in plastic package, and we are not talking about some plastic, but transparent plastic. I wonder if Philipp had tried to do that. Its a bit too late for us as we had completely changed the HV power supply to different vendor (there were some additional considerations and chain of reasons) on our SX100. But for more recent SX100 HV tanks, where glow discharge suppression is not jeopardised, repairing LRD seems to me attractive cost efficient solution.
And even if it would be that model, I cant find it anywhere on stock. oh something changed: it is available on mouser