You must have acceded peak current and the mosfet is gone. If they are both gone, no point repairing or replacing with same HVPS, it’ll happen again.
If interested, I have a much more powerful power supply for sale here: https://www.ebay.co.uk/itm/276921910331 > On 15 Feb 2026, at 10:54, 'JBro63' via neonixie-l > <[email protected]> wrote: > > Hi all, looking for insight in to PSU problems. Have had two NCH8200s fail > very close together after only a few weeks of use. > > In December, I finally got round to building four IN-12 4 tube clocks using a > new PCB and some leftover tubes and drivers. They are driven using a K155ID1 > for each tube (no multiplexing) and MJE340 for the INS-1 colons. Current > limiting resistor is 18K. Each tube anode has a PC851 optocoupler to turn the > tube off if no presence is detected. > > My previous IN-12, IN-14 & IN-18 clocks use the 8200 or 6300 and are still > going strong. They are driven using HV5530s. > > Both 8200s have gone full short across the input. Anything about the K155ID1 > / PC851 that is harsher on a HV supply? Anything I can check for with a scope? > > Thanks > > -- > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] > <mailto:[email protected]>. > To view this discussion, visit > https://groups.google.com/d/msgid/neonixie-l/a93fbd9d-36aa-4791-bffa-54f7d2514cdfn%40googlegroups.com > > <https://groups.google.com/d/msgid/neonixie-l/a93fbd9d-36aa-4791-bffa-54f7d2514cdfn%40googlegroups.com?utm_medium=email&utm_source=footer>. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion, visit https://groups.google.com/d/msgid/neonixie-l/7DD05D53-6622-4886-A757-C082D321BC7B%40gmail.com.
