On 2021-10-17 11:12 p.m., toby@telegraphics.com.au wrote:

Hi,
Was testing my Tek 606 yesterday, and after power on and the next few minutes it made about five "snap" discharge sounds with fluctuations in brightness. After the last one, I lost trace permanently.
Checked LV rails and all are spot on except for the +30 and +120 unregulated, which are off the HV transformer secondary. Before I go any farther, does anyone have a good idea of what the discharges might mean?

The next step seems to be to power the board to investigate further.

The HV section is basically this (but my unit shows some updates as mentioned previously): https://imgur.com/gtO35ue

Can anyone comment on whether it will be safe to operate this topology onnected to the LV supplies but with the CRT disconnected completely (grids, filament, cathode)? Or should I test with the CRT connected?

Either way I think I will probably be able to do this with the HV safety shield in place until I reach a point where I need to measure the HV itself.

--Toby

--Toby