Andy
Removing the HV board is a PIA as you have to unsolder 11 or so connections on the top of the board and a screw holding the heat sink for the oscillator transistor before you can work it out. Gets easier the second or third time. I wish TEK had used push on connectors like on the 576 boards.
Be careful bending the plastic clip in supports that hold the board, very easy to snap off.
Definitely was a bad design for working on the board in the cabinet, should have had the side rail removable.
Chuck
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On 5/3/2021 3:02 PM, Andy Warner wrote:
I bought a mostly working 577/D2 recently.
What I regard as the most serious problem with it is the trace intensity.
What I see is that the maximum intensity occurs at approx 60% of the front
panel adjustment (R1200) - moving it either direction from the peak results
in a dimmer trace.
The bulk of the trace (when the beam is moving fast) is not particularly
bright, but the start and end of the traces is good.
I have cleaned and checked R1200 operation, and I believe the pot is good.
Also, the dimming signal from the collector supply board (R592) seems to be
correct (e.g. near zero V when the collector voltage is non-zero.) However,
I don't really see an obvious dimming effect on the trace when I turn the
collector supply down to zero.
I have not yet been able to measure the HT voltage (looking for a probe to
help me do that - advice welcome.)
In the interim, I wanted to trace the operation of the Z amplifier circuit
(Q1222,1226,1234), but the service manual I have (thank you Artek) is
silent on removing the deflection amp/high voltage board.
It honestly looks like a royal pain to remove for service - does anyone
here have any hints and tips ?
The schematic has a couple of helpful waveforms shown, but I have zero idea
how you are expected to probe up the board, given the location of the
side-rail that obscures the lower half of the board.
Any 577 owners out there got advice to share ?
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