Recently, I've had an experience many of you will undoubtedly identify with. Before I get to the details, a bit of background, as I don't post here too often. You see, I may have become a collector inadvertently. This wasn't planned. At first, I wanted some awesome tools so I could take advantage of new skills I've been learning. After repairing these tools, which are inevitably broken in some way or another, I have become enamored with the design intelligence, commitment to build quality, and the overall feel of these pieces of equipment. Surely many of my dear comrades here have shared this experience, and know exactly the path I have traveled. I mentioned that I became a collector; I'm not sure if having one of a thing makes you a collector, but in the case of 1990's era logic analyzers, owning two of these behemoths surely qualifies me as a collector.
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My workshop has one fatal flaw: Its walls are fixed. By this, I mean they do not expand as I acquire additional equipment. I have been paring down the materials and equipment in the workshop to make the space more conducive to, well, working. When it is overly cluttered, any new project starts with clearing a space for that project. The unintended effect is that, too often, I do not start the project. This brings me back to my recent experience.
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I've determined that I am simply not using my wide-bus logic analyzers, of which I have two, a HP 16500C and a newer Agilent 16702B. Both of these are amazing, though I must admit the physical build quality of the 16500C still leaves me agape. The 16702B, no doubt, is of higher complexity overall, evident when one considers the chips and software behind its operation. These are quite large, and the pair, including their accessories, take up a substantial amount of space in the workshop - even though they are in fairly 'cheap' offline-style storage places. I, therefore, decided to take them out and power them up, with the intention of assessing their condition and capability. I resolved to sell one of them.
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The 16500C is my favorite, even though it is less capable and substantially more difficult to use than the 16702C. I love the 9 inch Sony Trinitron monitor embedded into its frame, which, by the way is a diecast monster - reminiscent of the Tesla Cybertruck single die cast chassis. I chose to explore that one first. I heaved it on the worktable and simply plugged it in. Here's where the trouble begins.
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The device powers up, but nothing appears on the display. I mean to say the fans run. To paint a clear picture: The monitor is power on. When I remove power, the deflection coil fields collapse, and I see the telltale sign of an electron gun doing its job. Also, I had replaced the Quantum Fireball SCSI disk with a SCSI2SD arrangement a few years ago. Just in case, I reverted to spinning metal, even though I should have seen something on the display before the disk was accessed.
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I proceeded to do basic troubleshooting, starting with the 1st commandment: thou shall check power rails. All power rails on the monster power supply are doing exactly what the service manual say they should. I also pulled out every module from the chassis. Still, no sign of anything, ever, on the monitor. I pulled out the logic / CPU board - the bottom one on the stack. Here, I checked connections, reseated the SIMMs, and generally did the usual mechanical-first troubleshooting, hoping for a wonky connection. None of this had any effect. Interestingly, I don't get signs of life from the microprocessor. The floppy drive never lights or seeks, and the CPU board remains surprisingly cold, even after being powered for over 1h.
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The level of service manual that I have stops at the level of module replacement. By this manual's logic, I should replace either the CRT, the logic board, or both.
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Of course, it worked when I put it away last, and nothing unusual happened when I first re-powered it. I noticed some dipped 3-legged capacitors that look identical to the Kemet ones that fail on IBM PC 5150 motherboards. Possibly something like this has failed, and taken out a board-level fuse with it? This would leave the power supply rails intact.
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My intention is to sell the 16702B. It is in excellent physical condition - clean, unbroken, and without missing parts. Unfortunately, the display shows some banding which gets far better after it warms up.
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Given my difficulties with the 16500C, along with the lack of use and my space challenges, I'm strongly considering selling it as well.
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I'm in the US, specifically in Raleigh, North Carolina. I would love to chat with any fellow test-equipment-anonymous members. If anyone has ideas on how to bring the 16500C back to life, please reach out. If you're interested in buying one of them, let me know - especially if I don't have to box it to ship it.
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Thanks for being one of my dear readers.
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NickyDoes
