Thanks.
I am in no way more enlightened by that translation😕
Looks like they recapped all the boards, and replaced a trim pot. Interesting that the 250 volt caps were much smaller than the 100 volters...and the new trim pot was far bigger than the old...again, 😕
Also of note, for some reason they had the output cable of the dc supply well into the case, loop, and tie wrapped to the line cord. Perhaps the intent was to inject some warm sounding line noise into the dc runs?
I wonder why?
jn
You should see some of my milling bits. Honestly, I can't. .1mm bits. And a tube of .05mm bits... (I'm not sure, it may be empty.)😱 Explain to me why all the watch repairmen are over 60 again??
That's not maximum, they have a few lines that could have been eliminated..
Bet they don't know where all the ground return currents are..
jn
Just imagine how long it would take to machine a batch of boards...even 0.5mm bits are a pain, 0.1 and smaller is just silly🙂
The boards look etched not machined though.
No and everything is nicely spread out, I like to cram everything as close as possible, paying homage to any thermal considerations etc and putting high current devices next to there respective connectors.
The boards look etched not machined though.
No and everything is nicely spread out, I like to cram everything as close as possible, paying homage to any thermal considerations etc and putting high current devices next to there respective connectors.
No, I agree they are etched. I hadn't expected the picture resolution to be high enough to notice it, but after you mentioned it I zoomed in.
The small bits are soooo difficult to work with (ie, keep them in one piece), that I'm working on the plunge micro-edm set. Buying a 2 or 3 mil steel wire is so much cheaper than that size drill. Plus, edm cuts steel at C60 as if it were dead soft, so I don't have to anneal anything first. Problem is getting linear shafts and bearing with zero clearance, what I just bought has 2.6 mils total slop.. Where's that .001 inch brass shim stock??
jn
Fascinating! I didn't know that much about the circuit boards that I first worked with 30 years ago. The 'plastic' on the second stage board is all the solder mask that I would allow to facilitate better solder joints, without shorts. The board material is polyamide, and the boards are gold 'plated'.
The IC is always a servo, and we found the ad711 to be very good for the job. Today, I would use an OPA134, as it has better specs. and is also available in 8 pin mini-dip.
The circuit boards were made with a million dollar computer at Fairchild Instrumentation where Carl Tompson worked at the time. He did their boards as well.
The IC is always a servo, and we found the ad711 to be very good for the job. Today, I would use an OPA134, as it has better specs. and is also available in 8 pin mini-dip.
The circuit boards were made with a million dollar computer at Fairchild Instrumentation where Carl Tompson worked at the time. He did their boards as well.
John, the $value of the computer is not really significant - they were ALL in that price range then. It only bought you 16bits and 32Mb RAM!
It looks to me that the PCB masks were made by using a standard photoplotter (the thermal relief vias in the ground-plane are a giveaway) and then exposing a slighter bigger pad in negative to produce the top layer maximum copper.
That doesn't sound quite right (MARC will know!) but I think that's what we did in the 80's.
It looks to me that the PCB masks were made by using a standard photoplotter (the thermal relief vias in the ground-plane are a giveaway) and then exposing a slighter bigger pad in negative to produce the top layer maximum copper.
That doesn't sound quite right (MARC will know!) but I think that's what we did in the 80's.
Old news, but the smaller caps are Roederstein MKT1813, stinkin Polyester.
(got about a thou of those left)
Eeh, 30 years ago I had to register for a time window at SARA, the A'dam calculus center, a Cray Y-MP4/464
Or polyamide- especially after it has (inevitably) taken up moisture. And look at that DF! 😀
Not that any of that makes a difference- the circuit is a good design and doesn't have any goofy aspects that would demand (from a performance POV) some exotic material.
Well folks, this is what separates my associates from my critics. We care about everything that we can think of and what we can address. Others simply don't consider them important. I have some early, (pre-CT designs) any offers? '-) Of course the layout is different, and FR-3 is probably the substrate, the power supplies are different, etc. etc, but it shouldn't make any difference to many of my critics. '-) [I've been wondering what to do with these boards, they are too valuable to just throw away]
Eeh, 30 years ago I had to register for a time window at SARA, the A'dam calculus center, a Cray Y-MP4/464
41 years ago I exchanged my batch of students of economics with other students from abroad using AIESEC's punched card program and data. That year it was Bordeaux, but I didn't go, and since I was the Boss, I didn't let anybody else go either, because there was no need for anyone to go, we ran trial tests and came up with fyling colours. First offcial run, 98% exchagned, the last two were exchanged the traditional way, by bartering. 😀
Then I had to wait until 1983 for IBM PC production volumes to catch up with the demand, and triumphantly bought my first PC, from Big Blue, in Wimbledon near London. No other way, as some nitwitted dodo put the IBM PC on the list of protected military technologies, not to be sold behind the Iron Curtain. This sure miffed the Russians, as their embassy staff had to buy a new PC every day and ship it back home. That machine works in a charity I donated it to without a hitch to this very day, I just go to clean it up once a year. Intel 8088 running at a lightning 4.77 MHz rate, shifting them there bits around it gigantic 640 kB memory!
Ah, those were the days of thunder! 😀
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John, is that an offer? How much for a stereo setup?
Or maybe I don't qualify, since I'm not your critic? 😀
It isn't just the cost of the computer, it is also the cost and sophistication of the SOFTWARE. Amateurs may get access to some pretty good software today, but I have never seen the power of that 30 year old stuff on a home computer. The real improvement is cost and speed with today's technology, it seems to me.
Then why circuit boards with poor DF and other PCBs from mechanically inferior materials?
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