RE: HELP: Indy Won't start without a reset @ power-on, otherwise works.
While I understand the master craftsman's moto of: "you only need a hammer and a chisel"...I mean look at what the great masters of art produced many hundreds of years ago with primitive tools....if they can do it you can do it. Unfortunately, I'm not a master craftsmen (one of my many burdens to bare).
That's why I call it a "cheater tool", it is...you're right in your summation that gives a less-skilled worker a chance of resolving more complex issues...bingo. I think we just described my situation. I'm not classically trained in this stuff (I just got college Physics and that was it). So I learn by encountering and trying. I hear about tools of the trade used in repair shops...I listen to that info and take auction, if that's to my benefit. Because often times, repair shops have no documentation, the unit is a black box and whatever kind of circuitry the technician can visually identify and assign purpose to. Also most of my repair work needs to be POWER OFF testing as something has blown and it may continue to to further damage to device if I leave it on start measuring voltages and such (sometimes you can do that, other times...I'm not comfortable with that risk because it's an unknown to me). So most of my experience is that, while having a system malfunction but work isn't common for what I tackle.
Many of the scenarios you allude to in your other postings seem to be professionally work related, yes? Okay well this may not be the same situation. Unless you job is reverse engineering (in which case I wish you'd go into real detail because I'm here to learn, if you have something to teach) normally businesses choose platforms and system with enough documentation/support to achieve their business needs (prototypes, new products, in-house equipment/tool development, etc). They often don't waste time working on blackbox devices unless that's their job. Many professionals can become "comfortable" being able to do that kind of detailed work (because they do it everyday and that's what they see) and they have the documentation so devices with a problem now resembles their work challenges/problems (when all you know how to use a hammer, everything looks like a nail).
In this case we are dealing with "prosumer"/consumer systems. Sold without any technical info aside from pinouts, never intended to be repairable, intended to have a service contract only and replace large & modular components. I have no diagrams, I've never seen anything like it before at a design level (as I've never designed a circuit of any real function), and I now have the challenge in front of me of repair it or dump it.
The huntron (with proper research - which I spent a consider amount of time on) has a critical but narrow role in black-box, powered-off, testing. If you have other recommendations, please post them as I want to learn more and I can only do that by being told new things. ASA, which is legitimately used around the world by many companies, excels at giving a qualitative value or reading to something that can be repeated with a duplicate device. It's more than a number, but a behavior.
Then I, as someone who doesn't have access to any other documentation or information, have a basis to say (not with 100% certainty but over 90%) that two things are "alike" or "dissimilar" using the human visual system in a novel way to compare responses. Along with gaining knowledge on what testing parameters should be used under what circumstances, the huntron has allowed me to...so far in the past 2 month:
1. Fix a shorted/damaged Fuel/Tezro V10 graphics card (works now)
2. Found/Fix an slightly damaged DS1780 in a fuel PIMM giving slightly skewed BUT REALISTIC values!
3. Same PIMM above, fixed the main PIMM 5V VRM due to shorted flyback diode that clamps the gate signal on one of the driving MOSFETs (replaced both diodes to ensure same triggering due to standards of then versus now on diode bias values). PIMM has perfect voltages, however I still have an SRAM addressing issue, you're free to check it out on the PIMM repair thread...I need some help knowing where the connection is from CPU to external SRAM for a R14 MIPS CPU...too many pins to check.
I do have other smaller instances that helped a lot...but you could have done those on a multimeter (so I won't include them). But the point was, the Huntron has already proven it CAN help me solve real problems and find a solution. So no, just like the guy I bought it from, you're saying that everything is fixable with a running system with real-time instrumentation and tracking down problems. I agree that's the best way if you CAN run the system and you have the knowledge level of the circuit to meaningfully evaluate what you see and you have the lab equipment for that visualization, but that's not where I am. I'm just a normal person with a want to fix my SGIs and general consumer appliances (because I don't want to buy new ones). So that's the skill set I'm currently learning.
What I learned very recently is (while not 100% in cases) a "Repair" mindset isn't an overlay of a "designer" mindset. A repair person doesn't need to be a designer to repair most things that fail in the field (if the designer did a good job). I'm not hear to improve or alter the Indy's operation...only to correct it. I do not need it to be better than it was, only as good as it was.
So while I wish I had the ability to simply look at a circuit and all the nearby components and their layout suddenly shows their functions to me...I don't have the level of experience yet to claim that. I'm okay with VRMs...but that's because I've been focusing on power issues first in my learning for the past a couple years. In the meantime as I'm learning, I have things to fix.
The Huntron let's me cheat...but you know what, we are not in school here and results speak. If I can use a special tool and find an issue in an hour than it's a valuable tool to me.
Everything I post is about my collection and now (after decades) the need to repair it. No one else is going to repair it for, so it's up to me to fix my own stuff. I like being in this group because, normally, people share their findings and experiences to help others. Members have different disciplines so they can each contribute something new to help solve the problem.
How anyone achieves success in fixing their SGI is less important than is it really fixed. I'd love to know more and "how it happened" and all that. But in real terms, it's a hobby and it's just not that important to spend too much time on.
But since my collection is important, I've invest a lot of time and money (and learning) to try to fix it without simple, gross, part swap. Now I can fix things that have been issues for years now and hopefully I'll get through all my units again get them back to fighting form.
So yes the Huntron is for newbies, but it helps me learn and gives actual, real world, successes. It's tool that stays on my bench and after I'm done with my multimeter, it's what I reach for next.
Never got the original Huntron probes (I use the needle sharp bent Pomona probes), not the best but workable.
Please see if you can find a moment to look at your Indy and see if you have an alternate theory of operation to check out, I'm all ears.
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