test-drb September 2014

test-drb@ccmp.vtda.org

188 participants
251 discussions

by bobvines00＠gmail.com

Tony, et al., On your Rainbow H7842 PSU pinout you list pin #1 as ACOK H. Do you know what monitors that signal? Is it the AC side OK or the DC output OK? I'm guessing that it monitors the AC side to ensure that the incoming "mains" voltage is high enough to not damage the PSU. Is that correct? And nothing monitors the DC output(s) for correctness? ===== For pin #2 you give "IOWR4 L (connected via a jumper)." Does this mean that it is pulled down as "true," and if so, by what? Do you have any idea about whether it can be ignored for use in a DECmate II or if there is a jumper for DECmate use or is it always jumpered? Can you tell me what "IOWR4" means or stands for? ===== I have a question about using an automobile's headlamp for load testing this PSU. Do I need to use an increasingly rare 6V headlamp or can I safely use a "relatively modern" 12V incandescent headlamp? Will the 12V headlamp draw enough to safely load the 5V portion of the PSU? ===== There is another connector coming out of the PSU that just hangs on a plastic clip on the superstructure, presumably for another application that the DECmate II. Since it's probably only one wire, I figured it's some PC-imitation Rainbow-ism [or the Pro 325?] which is never used in the DECmate II, etc. Do you know what this "extra" connector might be for? ===== My next (dumb) question is: "Is the Rainbow PSU a switching PSU?" I assume that it is based on its size & weight, but would like expert opinions to verify this. Thanks, Bob

9 years, 7 months

FS: Macintosh SE/30- Needs replacement analog board- Comes with one

by slandon110＠gmail.com

Just clearing out more of the collection. A mint Mac SE/30 with 5MB RAM 80MB Hard Drive No yellowing on the system at all, comes with keyboard and mouse which is also mint, along with the original owners manual and carrying case. Needs an analog board installed and new one comes with it. $100 plus shipping for it.

9 years, 7 months

Further PDP-11/05 debugging -- core memory faults

by anders＠abc80.net

> Date: Sat, 27 Sep 2014 22:11:52 +0100 (BST) > From: ard at p850ug1.demon.co.uk (Tony Duell) > To: cctalk at classiccmp.org > Subject: Re: Further PDP-11/05 debugging -- core memory faults > Message-ID: <m1XXzHa-000J4dC at p850ug1> > Content-Type: text/plain > >> >> Further investigation reveals that the connection between FD1 on the >> card edge connector (the XS05 signal) and pin 7 of the 2501 at E22 is >> broken. This, I believe, is a matrix wire (or "magnet wire" from the >> engineering drawings) meaning that I've got a broken wire somewhere in >> the core mat. > > I would just trace the tracks, both visually an with an ohmmeter, from > the edge conector pin to the core mat and from the core mat to the diode > array. Just in case. > > Incidneatlly, no matter what it says on the cover over the core mat, you > can take it off quite easily without damage. Just don't drop it on the > corse. > > If it is the core address wire in the mat, you may have big problems. > Some of these mats had the cores cast onto the array of wires, no > pre-made cores that were threaded with the wires. In which case, > replacing the wire might be impossible. It's possible to replace a wire in a core mat, I have made it myself in a core pack that belongs to a PDP-8/L. Depending on the sizes of the cores it migth be more (or even much more) difficult. If the wire is broken outside the mat, it?s possible to extend the broken wire a bit and put in a new piece of "fresh" thread. I used a good stereoscopic microscope which essentially made it possible. You also need some time and a steady hand. > > My first throught was 'have a go anyway. If you wreck the board, well, it > doesn't work now'. And then I thoguth that no, you should treat it with > care. Even if you don't have the skill to fix it now, you might do so i > nthe future. Or somebody else might have a go. In any case, you don't > want ot make thigns worse. > > -tony I do agree upon that. The worst thing that could happen is if you crush a core... /Anders

9 years, 7 months

Exec-PC BBS

by cctalk＠fahimi.net

Anyone know the status of this BBS? I.E. is it fully operational through the Telnet node or is it just a shell of its former self? I signed on a few months ago and tried "subscribing" but I am still in demo mode (oh that brings back memories!). It would be very cool if it is "fully" up and you can dl old files/utils/apps etc. Thanks. -Ali

9 years, 7 months

Value of a Tantalum Capacitor

by robert.jarratt＠ntlworld.com

In investigating the fault on my H7874 PSU I desoldered a tantalum capacitor which I have broken in the desoldering process. I can't tell its value, the markings are 224 E5Z on one side and 038 ASF on the other side. >From these markings, can anyone tell me what value/spec the capacitor has? Thanks Rob

9 years, 7 months

P112 parts on their way

by dgriffi＠cs.csubak.edu

On a homebrew synthesizer list I presented my frustrations on dealing with Mouser and filling kits. Everyone there who sold kits did a marathon at the kitchen table rather than having the part supplier do the kits. I feel that I've been making a big production out of a small one. I should have the box of parts by Tuesday, I think. -- David Griffith dgriffi at cs.csubak.edu

9 years, 7 months

Computer Conservation Society visit to Bletchly Park

by dave.g4ugm＠gmail.com

Folks, Well I started my retirement the way I intend to continue with a trip to IBM Hursley's museum. I posted a few pictures on Facebook but any one should be able to view them without logging in. https://www.facebook.com/media/set/?set=a.10205102010936371.1073741828.14268 00809 <https://www.facebook.com/media/set/?set=a.10205102010936371.1073741828.1426 800809&type=1&l=ff0e40da08> &type=1&l=ff0e40da08 Dave G4UGM

9 years, 7 months

dumping core from pdp8 to serial.

by simski＠dds.nl

Hello all, The pdp8/f we got last week is working now, after forming the capacitors on the lineair powersupply and testing it with dummyloads. there is a 8kword and a 16kword corepack in the machine. we would like to dump the contents of the core to serial to preserve the original contents for later examination while we can to tests with the machine. is there a way to do this, using a empty part of memory and a M8650 uart? -- Met vriendelijke Groet, Simon Claessen drukknop.nl

9 years, 7 months

Unibus/qbus wire wrap tool

by roeapeterson＠gmail.com

I know I've seen this before, but I can't find it just now. I need a wire wrap tool for qbus/unibus. What size for those pins? Thanks.

9 years, 7 months

FS: Amiga 3000 With 16MB ZIP RAM 2MB CHIP 1GB Hard Drive & Extras

by slandon110＠gmail.com

Ive had this Amiga 3000 for a couple weeks now, and upgrading it is just out of my price range, It needs to go into the hands of someone who will appreciate it Its in unmolested condition with 16MB hard to find ZIP RAM installed 2MB Chip RAM Has the Original Kickstart 1.4 ROMs installed. 1GB Hard Drive with Workbench 2.03 installed. A set of 3.1 ROMs will come with it It will also come with the following items not installed 36GB SCA Hard Drive with 50pin Adapter- Prepared for the Amiga, Just plug and play Internal 50pin 4x36GB External SCSI array that works with AmigaOS Keyboard & Mouse This thing is mint Pics are here https://flic.kr/p/pjqeWU No monitor included. It takes a standard VGA CRT $800 shipped for the system. Or I will gladly trade for a nicely expanded Amiga 1200 system

9 years, 7 months

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test-drb September 2014