On Thursday, 6 March 2014 21:39:29 UTC, Samuel M. Goldwasser wrote:

One test to confirm it's the tube and not the power supply is to put a fan

on the tube. If it's the tube, that should enable it to stay lit at least

for a longer time.

I tried this and it didn't seem to have an effect. A write up of experiences so far, along with a few photos, can be found at:

http://designspark.com/eng/blog/brea...tage-gas-laser

(This assumes that the 3.7 kV value in the Laser FAQ is correct. It's from

the spec sheet but I have not measured a healthy one.)

This still has me wondering and in particular when I look at those old resistors and caps etc...

Helium ordered so will try a soak in any case.

Possibly time to install a modern laser tube or head.

Never! )

Cheers,

Andrew