test-drb November 2005

test-drb@ccmp.vtda.org

255 participants
692 discussions

how sloppy are speed tolerences in QIC drives

by ajp166＠bellatlantic.net

> >Subject: how sloppy are speed tolerences in QIC drives > From: compoobah at valleyimplants.com > Date: Sat, 12 Nov 2005 13:36:17 -0600 > To: <cctalk at classiccmp.org> > >I'm trying the vinyl tubing approach in replacing the drive roller, since it sounds like it would be difficult to slide in a different QIC drive when I need to use tape (no one suggested tips on that). How "sloppy" can the drive roller dimensions be? is there a feedback loop for speed regulation that interfaces directly to the tape, or does it rely soley on the stepper motor and parts dimensions? I think I'm about 1/32" too large, but it could be bigger, since it's hard to measure goo, not more than 1/8th, though.=0D=0A=0D=0A Well, the TU58 servos off the motor and I found it tolerent of at least 1/16" variation. If the drive servos of the data then tolerences are far greater. Allison

18 years, 8 months

Reverse Engineering 15 yr old electronics

by dave04a＠dunfield.com

>One thing I forgot to mention in my last message. Get a good continuity >tester. 'Good' means one that is not fooled by diode junctions (and >preferably not by low-ish resistors), one that doesn't supply enough >voltage or current to damage anyting, one that beeps, and one that beeps >quickly (you want to be able to 'stroke' a probe along a line of pins to >see if a given connection goes to any of them). A useful trick I sometimes use when I have trouble following a connection (especially those which "disappear" into a multi-layer board). If you just can't figure out where a signal goes - cut squares of tinfoil, and press them against sections of the board with a firm sponge (something with enough give to let the foil seat against all the pins). Then using a good continuity tester such as Tony describes, you can quickly cover large areas to quickly narrow down where exactly a signal is located. (use foil squares sized as needed). Obviosuly you do not want the board powered at all - insure that caps are discharged, batteries removed etc. Regards, Dave -- dave04a (at) Dave Dunfield dunfield (dot) Firmware development services & tools: www.dunfield.com com Collector of vintage computing equipment: http://www.parse.com/~ddunfield/museum/index.html

18 years, 8 months

Orphaned OS thoughts

by James＠jdfogg.com

While reading an old resume, I came across something I forgot about. I used to admin some 3Com 3+ and 3+/Open systems. 3Com made the hardware (beefed up PC stuff) and wrote or owned the OS. Anybody know what became of 3+/Open? -James James Fogg JD Fogg Technology Consulting 18 Watershed Lane Wilmot, NH 03287 (603) 724-2243 www.jdfogg.com

18 years, 8 months

Power connectors?

by fireflyst＠earthlink.net

Hey does anyone know where I can buy 3 prong Molex connectors, particularly those used to connect a QBUS box to a DEC power bus, and the one that goes >from a cable to the power bus connector? I can't find them anywhere on Molex or AMP's web site.

18 years, 8 months

R-E 68000 PC articles that were mentioned

by aek＠bitsavers.org

>I have a book called "Build your own Z-80 computer" by Steve Ciarcia. >Is this the sort of thing that would have some interest in an e-version? I'm sure Mr Ciarcia would be interested if this were put on line, but not in a good way. >Is there a fast way to scan bound materials without butchering them? It is MUCH less expensive to find a second sacrificial copy of the types of bound documents that classiccmp-ers would be interested in than the cost of something like a Kurzweil book scanner. The Mustek Opticbook USB scanner is OK for book scanning, but is isn't particularly fast.

18 years, 8 months

=== IBM 5110 / 5120 terminator ===

by f5inl＠wanadoo.fr

Hi ! Could anyone give me the REAL pin assignment of the terminator used on the IBM 5110 / 5120 systems ? Has anyone build such a terminator ? I tried to build one and I'm fed up with getting always the same error : I can obtain the file list (using basic command UTIL DIR,D80 or UTIL DIR,D40) but 5 seconds after giving me the file list, the systems blocks, the promt disappeared and I must restard all... No led is lightning on the pannel...Sometimes I get the 24 or 26 error code (''diskette error...''is only said in my reference manual : what a help !). Very strange diagnostic... Thanks for your help ;-) Fred.

18 years, 8 months

how sloppy are speed tolerences in QIC drives

by compoobah＠valleyimplants.com

I'm trying the vinyl tubing approach in replacing the drive roller, since it sounds like it would be difficult to slide in a different QIC drive when I need to use tape (no one suggested tips on that). How "sloppy" can the drive roller dimensions be? is there a feedback loop for speed regulation that interfaces directly to the tape, or does it rely soley on the stepper motor and parts dimensions? I think I'm about 1/32" too large, but it could be bigger, since it's hard to measure goo, not more than 1/8th, though.

18 years, 8 months

continuation of R-E 68000 pc post

by compoobah＠valleyimplants.com

The Rest of the Story: inexpensively- does Al have that capability or does he only do ring-bound stuff that you can take apart?

18 years, 8 months

removing parts from PCBs

by compoobah＠valleyimplants.com

Two-leaded passives are easy to get with a soldering iron and a pair of curved-nose hemostats (check with friends in the medical profession- those and dental tools (picks, explorers) are really convienient to have- if you're extremely lucky you'll find someone who's getting rid of a unit- they have air/water syringes (great for blowing out small stuff) and high-speed air turbine "dremel" type things- tres useful). Just clamp the hemostat to one lead, touch a small soldering iron to the back, pull, same with other lead. They're cheap new, but sometimes I don't want to go out to get them. SMTs are a bit harder, but I've done them, too.

18 years, 8 months

LA210 Schematics

by aek＠bitsavers.org

> Are the LA210 printer schematics/tech info available anywhere? http://www.bitsavers.org/pdf/dec/terminal/MP02007-01A1_LA210.pdf

18 years, 8 months

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test-drb November 2005