Quote:
Originally Posted by andy
Have you checked the regulator cathode current? It should be about 1mA with a black screen, and gradually decrease as the brightness is increased (check the Sams for the correct value). When it goes to zero, that's when the HV will start sagging.
If it starts out too high, it will drag down the HV, and could mean the HV is set too low. If it's too low when the screen is dark, it's a sign that the HV supply is weak, or the HV control is set too high. If it changes unpredictably, it's a sign that the regulator circuit isn't working.
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well if its not the crt at fault then its obvious the hv reg circuit is not working as it seems now but the cause has got me puzzled. the reg currant with dark screen and hv adjust low is 1.64 and hv adjust high is 0.93 bright screen hv adjust low is 1.16 and hv adjust high 0.20 ma. to get any decent hv the hv adjust pot has to be maxed. the 2 1.5 meg resistors are within range as well.