Help to repair oscilloscope Philips PM3207 (Algemeen)

door edison , Aveiro - Portugal, 06-11-2020, 00:39 (1483 dagen geleden) @ Onno-I

Interesting. The transistor and transformer do oscillate when the base is not too positive.
What is the frequency you used? The oscillator should operate at 30 kHz

The signal you use seems to switch the oscillator on and off. But it is oscillating when it should be off, and is drawing lots of current when it should oscillate.

Please disconnect T801 from R808. feed a 30kHz sine of 1Veff into R808 and look at the signals on T801 (not the HV winding).
Touch the connection of T801 to C804 with a small, well-insulated screwdriver, 750V AC should be here, you should see a small spark if you have the screwdriver 1 mm from the connection.

Hi.
I put new the V802, V803, C804, C806 and C807 and I did it (30 kHz, 1Veff). I don't have the 750V AC.
Then I removed the light bulb between Bc337 and T801, and the and the transistor burns.
For all this, I think the defect is in the T801 transformer.

--
From PORTUGAL, with regards
Carlos