7834 power supply in tick mode


ycui7
 

I have been working on my 7834.

Previously, the power supply goes into tick mode for a few time before the scope shows a trace. A few weeks ago, the scope give up start up and end up in a endless tick mode.

I have been spending time on and off for more than three weeks to figure out the problem. Recently, I was able the locate the issue at either high voltage board or focus board.

So, I was able to power up the scope when both high voltage and focus board are disconnected. Any time I disconnect only one board the scope failed to start. I don't think both of the boards have problem. So, I did some additional probing. Attached are the trace probed at the high voltage transformer output/HV multiplier input. (I did disconnect the HV multiplier input wire, and try to start the scope, same tick mode. This probably rules out defective HV multiplier.)

Does the dip in the beginning of ramping up confirms this is a failed HV transformer? Pictures here https://groups.io/g/TekScopes/photo/247104/0?p=Created,,,20,2,0,0

Additionally, will someone sell me a HV board?

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