One of the best parts about Hackaday is how much you learn from the projects that people tackle, especially when they are repairs on old gear with unknown failure modes and potentially multiple problems. By the same token, the worst part about Hackaday is seeing what other people are capable of and knowing that you’ve got a long way to go to catch up to them.
A case in point is [Curious Marc]’s recent repair of an old pulse generator. The instrument in question is an H-P 8082A, a device from a time when H-P was a place where “good engineers managed by even better engineers [wanted] to help other engineers,” as [Marc] so eloquently puts it. The instrument was capable of 250 MHz output with complete control over the amplitude, frequency, duty cycle, and rising and falling edge geometry of the pulses, in addition to being able to output double pulses. For an all-analog instrument made in 1974, it was in decent shape, and it still powered up and produced at least the square wave output. But [Marc]’s exploration revealed a few problems, which are detailed and partially addressed in the first video below.
In part two [Marc] goes after the problem behind the pulse delay function. He traced it to a bad IC, which was bad news since it was a custom H-P part using emitter-coupled logic (ECL) to achieve the needed performance that can no longer be sourced. So naturally, [Marc] decided to replace the chip with a custom circuit. The design and simulation of the circuit are detailed in part two, while the non-trivial details of designing a PCB to handle the high-speed signals take up most of part three. We found the details on getting the trace impedance just right fascinating.
In the end, [Marc]’s pulse generator was salvaged. It’ll go into service helping him probe the mysteries of vintage electronics from the Apollo era, so we’re looking forward to seeing more about this great old instrument.
Not to belittle the article or the project but sometimes I get overwhelmed by the beauty of the PCB or the equipment as a whole as ART. This was one of those times. In the 70s I imprinted on an HP gas chromatograph, the HP2000E and one of their early scientific calculators. So beautiful!
I love HP gear from that era. I used to have a mid-60’s vintage HP counter that was only off by 1 Hz at 10 MHz.
The best part wasn’t the fact that I bought it for $15 at a hamfest, it was running into a buddy of mine who is a retired HP engineer at that same hamfest and seeing his eyes light up. “Oh, I know the team that designed that one! They were just down the hall from me.”
I love the amateur radio hobby. You meet some of the most interesting people on the air.
My dad used to work for Systron Donner a zillion years ago, and it was never more than a blip on his resume by the time I came around, until we were at a ham buddy’s place for some reason. I noted a Systron Donner spectrum analyzer on the shelf and reported the model number. My dad’s face lit up like a christmas tree…
“I built the first 5 of those by hand.”
Said ham buddy was a little incredulous of the claim until dad started talking about the bar magnet they put on top of the CRT as a hacky way of pushing the scan line down to the bottom.
Light starts to dawn on the buddy’s face. “So that’s why my oscilloscope works underneath it, but not on top of it…”
Not sure if relevant, but a fun memory that surfaced after your comment.
Dan – that first paragraph is SPOT ON!!!!! 😀
That newfangled transistor stuff didn’t have the balls that a 214A had. Or the weight.
Hi. I am Matthew D’Asaro, the other engineer and hacker that Dan Maloney credited in his article. I restored an HP 8007A pulse generator and had to do reverse engineer a similar IC. You can read my HACKADAY post about my project at:
https://hackaday.com/2014/04/21/rebuilding-a-custom-ic-saves-hp-pulse-generator/
I have a longer article on my website at:
http://www.dasarodesigns.com/projects/reverse-engineering-an-ic-to-fix-an-hp-8007a-pulse-generator/
-Matthew D’Asaro
Thanks Matthew. Your post and methodology was the inspiration for this repair.
Marc
Great article! Downloaded and watched these when I was more-so off the grid last month. CuriousMarc has some great repair videos and I enjoy watching him sharing and working on the equipment. This assessment, design and build was great to walk through for sure… excellent really.
Struggling to not want a pulse generator now… though thinking to remind myself a curve tracer is first in line… or really the making of one.
Technically, for me, this all started from wanting to learn if I can make a TDS-8000/(B) plug-in module. Amazing the range of modules now in line… and I still haven’t found the PMI/Wavetek 1038 D14A detailed history or the pin assignments for the RJ21 Telco connection on the NS20 and/or NS201 and/or NS206! Still hanging on the 5000 series mainframe design.
Curious Marc has some other great HP equipment videos worth watching too.
I love resurrection projects! Check out another HP pulse gen resurrection project by a friend – from the Hackaday archives: https://hackaday.com/2014/04/21/rebuilding-a-custom-ic-saves-hp-pulse-generator/
I’ll second that sentiment. Although it’s always nice to know there’s more to learn.
I used to repair these in the 1980’s when I worked for HP in Rio, Brazil. If my memory serves me well they were designed & made in Boeblingen in Germany, correct? Nice repair work, you have mastered well some forgotten skills. And I love the way you work & think outside the box to fix it. And yeah there’s no fun in changing boards. :)
> By the same token, the worst part about Hackaday is seeing what other people are capable of and knowing that you’ve got a long way to go to catch up to them.
That just motivates me even more, nothing bad about it really.
I’ll have to pull out my HP 8012A and see if it is still working.