1S1 repair news :-)


Michael Dunn <mdunn@...>
 

Yoohoo. I'm making progress repairing my 1S1 1GHz sampling plug-in. The biggest problem was a kaput power supply filter cap - totally dead - well, many, many kohms ESR. Replaced the big old can with a part about 1/6 the volume, yet almost twice the capacitance, and much better quality to boot! Semiconductors aren't the only technology that's improved in the last 35 years!

Also paralleled the smaller final power supply output stability caps with new ones, again much smaller, yet more C's!

As for the six missing GaAs diodes in the sampling bridge and elsewhere, I got some SMT Schottky diodes as hopeful subs. The unit is now working somewhat - there are some triggering and offset problems. But, with the right settings and input, I can get a valid trace!!! Whether these probs are a result of the Schottkys, I don't yet know. All I can say is, it's VERY cool to scroll over a 200MHz waveform at 35ps/div! (yes, 35ps. 0.035ns!) Though a bit useless, as the risetime of the thing is *only* about 300ps...

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