Re: 5116+5D10 intensity problem


Harvey White
 

Have you (and can you) safely measure the high voltage when this wandering happens?  First, though, I'd check ripple and voltage on the supplies.  That you have no stable trigger tends to make me think (in general terms) that there's ripple on the power supply somewhere.

It's possible that the supplies start good, and then something changes in the supply goes bad and the ripple goes up.

Harvey

On 2/14/2020 10:57 AM, Yeun-Jung Wu wrote:
I just digged out the A3 HV board and checked all the transistors, diodes except CR247, CR298, which is a 10kV, 5mA silicon diode and a 800V, 25mA silicon diode, respectively. I forgot to check the thick film hybrid resistor R272, which had multiple wire juction at A, B, C, D, E, F.

I also checked two aluminum electrolytic capacitors, 10uF/100V, and 10uF/50V. Their capacitance were 12uF with serial resistor about 2Ohms at 100Hz.

Putting everything back all the symptoms remain the same. I wondered if there was leakage of CR247 or CR298?

Now the horizontal and vertical expansion was about 1.5 graticules and varing slowly. Read out was still way outside the limit of screen. "Possible under-sampling" red LED warning lit all the time, stable trigger was not possible.


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