On 20/09/14 6:55 PM, Richard wrote: I stand corrected, I wrongly thought it was fairly normal for TVs and CRTs. :-) --Toby

On Sep 22, 2014, at 1:35 PM, David Williams <dave at willomail.co.uk> wrote: It may be normal. It depends on how the various power supplies work. Old TVs would do this, newer ones generally do not. It happens if the sweep quits while the electron beam is still running and the accelerator voltage is still largely present. If the filtering on the high voltage has substantial capacity and the thermal mass of the cathode is significant, that will happen. In more modern designs things are likely to be more optimized, with smaller filter capacitors and smaller cathodes, so the beam will quit much more quickly. For a particular model CRT display, the question would be whether other units of that same model behave likewise. If not, then this would suggest something odd in the particular unit. paul

The brightness flickers on almost every ADM-5 I've come across due to intermittent poor contact in the brightness control. I once had a problem with one of mine where the display collapsed to a vertical line and then slowly faded out, however, I had not switched it off. This was due to a bad solder joint on a leg of one of the transformers on the monitor board. I think it was the horizontal driver transformer rather than the output transformer. The joint failed when I had the terminal open to work on a different problem with it. I tried it just now and when I switch it off, the display collapses quite quickly in both horizontal and vertical axes and fades very rapidly. I did not see a vertical line at any point and only see a bright dot in the centre for a short time if I switch back on quickly before the CRT heater has cooled. (The brightness also flickered until I fiddled with the brightness control...) As Mike Loewen suggested earlier in the thread, I wonder has the CRT been replaced by one with a longer than usual persistence? The monitor circuit does not have horizontal or vertical oscillators and relies on drive from the logic board to enable horizontal and vertical scanning of the CRT to take place. I wonder could a problem in the power supply cause the power to the logic board to decay more rapidly at switch off than the monitor power supply? I have another ADM-5 which has a logic fault which I have failed to fix using hints from the ADM-3A schematics. I have not managed to find any schematics for the ADM-5 and I would be interested in a copy if you manage to find them. Regards, Peter Coghlan.