开云体育

David,

Hopefully there is an active HP group where you can get more informed assistance on your 1740A.

I will say this: Many years ago,? I purchased a used HP all vacuum tube oscilloscope, which was initially a fine instrument. However, after a week or two, it stopped working. I opened it up and discovered that the deflection amplifier output tubes, which ran quite hot, were in sockets which were attached directly, and only, to a large printed circuit board. Those tubes were literally falling through holes in the PCB which were the result of the heat from the tubes dessicating all of the resin from the board over how many years old (Probably 10 to 12) it was.

Fortunately for me, I had purchased the it from a reputable dealer who, upon return of the HP o'scope, allowed me to apply 100% of its purchase price towards a used Tektronix 561A, along with a variety of plugins. I still have the 561A. It now lives in my closet, along with the plugins, having been supplanted by 46x, 5000 and 7000 series instruments. It still works and I had to dig it out last year to use as my 5000 required repair. The 561A did yeoman work once again, helping me to repair its somewhat newer brethren.

I guess the moral of this story is that HP was capable of, and did, build some excellently performing oscilloscopes, but their idea of quality construction wasn't even in the same league as Tektronix. This is why you see very few classic HP scopes. Worldwide, aerospace and military buyers prized the reliability and longevity of Tek o'scopes so, over the years, they purchased them by the hundreds of thousands. Also, because Tek o'scopes were so long lived, many survived long enough to be retired due to obsolescence, not failure, and surplussed out.

Regarding the 1740A: Just as the much older model of my experience, it is not exceptionally solidly built. Beware the Schadow push button switches. They are commercial grade parts and notorious for having corrosion build up on the contacts. They can be serviced but its not a congenial process, requiring the use of some somewhat nasty solvent based chemicals and a tiny bit of VERY fine abrasive powder which must be completely removed once its done its work.

Thomas Garson

Aural Technology, Ashland, OR

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