Re: Tektronix 547

Albert Otten

Not yet in the early S/N. The cap was added at S/N 5680.

The 547 CRT circuit runs the beam at full throttle during the power-on transient. Nobody wanted it to do that, it's just a consequence of the design. Apparently, it wasn't easy to prevent, because instead, there's a small axial-lead electrolytic cap in the horizontal amp whose purpose is to yank the beam off-screen. As it charges, the beam comes back. If it's leaky or shorted, the trace will stay off-screen.

Dave Wise

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