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Thread: Model 16 Renovation

  1. #1
    Join Date
    Jun 2018
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    Default Model 16 Renovation

    Some early notes on a Model 16 renovation.... resurrection? A little of both, I guess.

    A friend had this sitting in his storage shed in Fort Worth and he'd bought it moons ago when it was surplussed from CPE, Computer Product Engineering. I was surprised he still had it! I'd had a rental storage shed full of these old machines, though they weren't so old back then, but who knew anyone would actually want them or that I might as well? Alas. That's the confession part of this thread and as I stand before you today I hang my head in shame. Please don't ask me what I did with them. I'll lie if you do.

    First question was how to ship it to the northwest and have it arrive intact. Answer is -- you can't, unless you disassemble it and then ship it. We decided to remove the drives and cards and ship them in separate boxes. Then the shell of the M16 was packed well to keep the CRT in position and the case from breaking. A week later the boxes showed up and everything arrived in fine shape.

    M16-Renovation-1625.jpg

    The box under the table holds 2 15 Meg Hard Drive cases. Be awhile before I get to those. No bubbles shipped, but I have ST506 bubbles in storage--not that I expect they'll work.

    M16-Renovation-1628.jpg

    M16-Renovation-1629.jpg

    Quick look inside:

    M16-Renovation-1626.jpg

    M16-Renovation-1627.jpg

    M16-Renovation-1693.jpg

    Right off the bat there's a problem and it might be a show stopper....

    M16-Renovation-1694-2.jpg

    When I unpacked the M16 case I found a bit of metal that looked very familiar in the bottom of the box. Couldn't place it, but I kept it fortunately. It's the ferrite part of the flyback transformer on this Motorola video board. Somehow the brass rod broke releasing the ferrite in transit where it broke into 3 pieces. They're clean breaks and I have them all. I should be able to superglue it back together, replace it on the transformer and solder the brass rod back together. Ought to work fine. Close call!!

    The cards are amazingly clean and most, maybe all from a quick look are very late revisions. That's a double edged sword, but they're clean and the only problem I found on visual inspection was a PAL hanging half way out of a socket. Looked to me like it had never been fully inserted.

    Before anyone asks--I did not receive the Arcnet card. I have a box of boards somewhere and I might have one with those...

    Otherwise, the unit, though intact other than the flyback, is filthy. I don't see mouse droppings, but I see a lot of dirt and dead bugs. First thing is to clean it up. I won't even attempt to fire it up until i change the 3 usual caps on the 11082 supply, clean it all up, put it back together, go through the 2 drives.... And then I'll see what happens. Oh, and I had to order a very long handled 1/4" nut driver. Can't work on one of these without one of those.

  2. #2
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    Default

    Continuing along...

    M16-Renovation-1695.jpg

    M16-Renovation-1702.jpg

    M16-Renovation-1704.jpg

    M16-Renovation-1706.jpg

    M16-Renovation-1707.jpg

    M16-Renovation-1708.jpg

    During the disassembly, each subassembly I pull out is placed in a separate box along with screws and such in a baggie.

    M16-Renovation-1709.jpg

    As I disassemble I take photos of connections, orientations and like that. It's been quite a few years since I worked on one of these and I don't want to trust my memory. Why have to figure it out if I don't have to?

    M16-Renovation-1782.jpg M16-Renovation-1784.jpg M16-Renovation-1790.jpg

    M16-Renovation-1791.jpg

  3. #3
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    Getting down to it....

    M16-Renovation-1792.jpg M16-Renovation-1793.jpg M16-Renovation-1794.jpg

    Back panel removed and cleaned. I've already done the card cage and its frame and I'll post a couple of photos of that tomorrow...

    M16-Renovation-1798.jpg M16-Renovation-1799.jpg

  4. #4

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    Very cool, thanks for sharing! The 16A is my favorite because it can pretty much do everything a 6000 can (with some upgrades) but with a smaller footprint and is much easier to maintain.

    A few things here I want to reiterate.

    First, removing the floppy drives is probably the best step you can take to ameliorate potential shipping damage. Their concentrated weight just does not play well with the plastic case when thrown around.

    Secondly, one of the the best things you can do to ensure you put it all back together is to take lots of pictures. You'll never remember exactly where every screw and wire went without visual cues. And there's no excuse with the capability of modern mobile phones!

  5. #5
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    Absolutely agree on the 16A vs 6000! Cooling is better too, unless you have the "turbo mod" on the 6000, but that's another story.

    Since this is/was an Arcnet machine I want to mention something slightly tangential.... You know that there are 50 ohm and 75 ohm BNC connectors? I'm sure you do. Did you know that the center pin of those connectors used to be a larger diameter in the 75 ohm unit? This also applies to the 10-base-T BNC "T" connectors used with early Ethernet at RS and other places.... The problem comes into play when you have a 50 ohm system and someone plugs a 75 ohm male BNC into a 50 ohm female connector.. It spreads the center hole of the mating connector and from that point on the 50 ohm part is intermittent. This killed us in our networks, and some customer networks too. In house on the service end of things, we purchased all our connectors from National Parts and their stock was accidentally mixed--and at that time we didn't know about the size difference. I don't think anyone at Radio Shack knew. Drove us crazy! Anyone playing with old RS Ethernet cards or networking equipment be aware.

    Fortunately, BNC connectors are standardized now to the same size regardless of impedance. Or, the better ones are at least.

  6. #6

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    Quote Originally Posted by shank View Post
    Cooling is better too, unless you have the "turbo mod" on the 6000, but that's another story.
    6000 Turbo Mod? Is this different from the 68010 support?

  7. #7
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    Quote Originally Posted by pski View Post
    6000 Turbo Mod? Is this different from the 68010 support?
    Oh yes. Very different.

    Engineering never talked to us in Technical Support about hardware design. It wasn't that we were super smart or that they weren't, but there's a difference sometimes in what looks like a good idea but isn't workable in the real world. One of the big issues with the Tandy 2000 was the horizontal option board design. When you stack hot boards on top of hot boards you have to really pay attention to air flow or you start to cook components. When we saw the same design in the Model 12 (and similar) we were worried. Our department systems, which were usually loaded with cards, began to overheat almost from day 1 and we soon were getting reports of customer problems as well. Spontaneous reboots to component failure...

    To fix our systems we cut a large round hole in the back access panel and mounted an additional AC fan there blowing right into the card cage and across the cards and we verified that it worked with temperature probes. Problem solved, but the fan was loud and someone said it sounded like a "turbo" and so we referred to it in service as "the turbo mod." See Technical Bulletin 12/16B:10 for details. Unfortunately, there isn't a drawing of what the back panel looked like with the fan, but it's easy to visualize. Pretty snazzy... Not!

    R&D got back involved at this time and proposed some additional modifications and that became the basis of the Technical Bulletin. Modification kits were stocked at National Parts. We sent a few basic kits out from our department to solve problems in the interim before the kits were ready at NP. You may see some variation and that's why.

    The mod sort of blew the streamlined case work of these systems, but it did solve the problem.

    But! Following the law of unintended consequences... One of our tech reps had the unfortunate experience of popping 2 CRTs while replacing the case on one of these systems in our lab one day.... This resulted in Technical Bulletin 12/16B:29.
    Last edited by shank; April 16th, 2019 at 06:02 AM.

  8. #8
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    Card Cage:

    M16-Renovation-1804.jpg M16-Renovation-1805.jpg M16-Renovation-1806.jpg

    Next 2 show the broken ferrite from the Motorola video flyback transformer:

    M16-Renovation-1807.jpg M16-Renovation-1808.jpg

  9. #9
    Join Date
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    The 6000 that I had years ago had the 'turbo' mod.

    My first system was an upgraded II, much like a 16A but not white and one SS drive.....
    --
    Bughlt: Sckmud
    Shut her down Scotty, she's sucking mud again!

  10. #10
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    Power supply caps changed and Motorola video flyback transformer repaired...

    M16 Restoration-1815.jpg M16 Restoration-1816.jpg

    Superglued the ferrite back together:

    M16 Restoration-1817.jpg

    Now to replace it:

    M16 Restoration-1818.jpg

    If you look at the tip of the screwdriver in this photo, there's a nut underneath that the brass rod screws into. Once the solder repair is done I tightened the nut to hold the ferrite securely, but not too securely..

    M16 Restoration-1819.jpg M16 Restoration-1821.jpg

    I didn't get too wrapped up in making it fit like when it was new, only that it was all in place and secure. Also, didn't want to use too much heat around the ferrite.

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