test-drb March 2011

test-drb@ccmp.vtda.org

146 participants
225 discussions

8/L has been sold. Have ADM-3A for sale.

by charlesmorris＠direcway.com

The 8/L, ASR33, DF32 disk emulator project has been sold. Thanks for all your interest (and offers). Anyone who wants the DF32 emulator schematic and artwork, I can email you a copy. I hope someone can take my "first draft" and make a useful unit for those who are interested. I have a working ADM-3A that I may want to sell also. It has a homebrewed lower-case 2716 ROM (thanks Steve Loboyko for the font files). I installed the "optional" parts for current loop on the main PCB, and used it with the 8/L. The only thing that's missing is the little aluminum panel covering the dip switches. Any interest? Same deal as before, please email offers, "sealed bids". thanks Charles

12 years, 8 months

Altair 680 power supply...

by wh.sudbrink＠verizon.net

My Altair 680 has achieved the position of primary attention on my workbench. All of the ICs are socketed. Not having seen power in over 20 years, I did not trust the power supply as far as I could throw a bus. I pulled all of the ICs, attached dummy loads (automobile bulbs) and powered up. Sure enough, there was AC all over the place (where there should have been DC). I replaced all of the electrolytic caps and that got rid of the AC but some of the voltage levels are very wrong, at least as compared to what is written on the schematics. The worst offender is just off the "plus" side of the full wave bridge (BR-1). It should be nine volts but is actually at 11.5. This makes what should be the main five volt rail a little more than 9 volts... the far side of VR-1 (a 7805). The wave form coming off the transformer is really ugly not a smooth sine wave. I hate power supplies. I don't really understand, looking at the schematics, what this transformer should be doing. My guess is that it should be making a nice nine volt, 60 cycle AC sine wave with each of the two outputs 90 degrees out of sync? What could be wrong with a transformer that it would produce something like: __ / \ | \ / \_ / \ | / | / \_/ bent and very squared off at spots? My scope shows nice clean 120 coming into the transformer. How do I figure out a part number for a replacement transformer? Thanks!

12 years, 8 months

Perkin Elmer 7300 Pro System Museum Quality!

by mail.list＠analog-and-digital-solutions.com

Here's one some of you might like. Perkin Elmer 7300 Pro System Museum Quality! http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2738081449 Current bid US $9.99

12 years, 10 months

Stan Viet passed away

by evan＠snarc.net

http://www.legacy.com/obituaries/floridatoday/obituary.aspx?n=stanley-veit&… Very sad.

12 years, 11 months

Atari 800xl "translator disk"?

by dbetz＠xlisper.com

I have an Atari 800xl and a couple of 1050 disk drives. I also have two copies of the M.U.L.E. game on disk. Unfortunately, I can't get either to boot on the 800xl. I suspect that these are older games that were written for the 400/800 and may need the "translator disk" that allowed the 800xl to run games written for the older machines. Does anyone know where I could obtain a copy of this translator disk? Thanks! David Betz

13 years

Stag PPZ EPROM programmer

by coredump＠gifford.co.uk

I have a fine old Stag PPZ modular EPROM programmer: http://www.gifford.co.uk/~coredump/inst.htm#PPZ It takes plug-in EPROM (model Zm2000) and PAL (Zm2200) modules, called Z-modules by Stag. I've recently acquired a new module, Zm3000, which looks like a more recent EPROM module. The chips in the Zm3000 are date coded in 1993, whereas the Zm2000 is nearer 1988. The PPZ main unit contains a 6809 CPU and a small CRT display. Does anyone know anything about this system? What about other Z-module types? In particular, should the Zm3000 work with the PPZ, because I currently get an error message "Incorrect Mainframe"? Thanks in advance for any clues! (Virtually all I get from Google is a link back to my own web page!) -- John Honniball coredump(a)gifford.co.uk

13 years

CMD MSCP controllers

by aek＠bitsavers.org

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=200591760912 Seems like a decent price for a QBus controller. I seriously doubt anyone could build one for $125

13 years

need a Pentium 75 and heatsink

by chrism3667＠yahoo.com

hope this isn't ot if you have one in your stash, let me know

13 years

OT : old US Telephone hybrid ('Network' block)

by ard＠p850ug1.demon.co.uk

THis is off-topic, I know, but I suspect there are some people here interested in old telephones. I have a Western Electric 500 telehpne on the bench. The standard US rotary dial one. As you may know, all the small components and the anti-sidetone transformer ('induction coil') are in the metal box kown as the 'Network'. This is the normal type 425 unit Anyway, I've remvoed this from the rest of the 'phone by disconencting the wiring and drillign out the rivets (this was standard practice accordign to one of the official repair manuals I read). I can refit it using 6-2 UNC screws whcih are a perfect fit. The 425 network was not field rpeairiable, and I can see why. After bending up the tabs, I slid off the can to reveal the components in a particularlly evil potting compound. It's not hard, it's sticky, I can be scraped off (but I spent good quarter of an hour clenaing a screwdriver after this). It will soften with heat (in fact a hot air paint stripper gun wil lget it to drip off, but I was gettign the thing so hot that the plastic terminal board was softening too). No solvent I have tried will remove it. The BSP docuemtns simply call it an 'insulating medium' which is not much help :-). Has anyone ever repaired such a Network block and knows how to shift this stuff? -tony

13 years

Smoke From PSU Socket

by tshoppa＠wmata.com

> Also I don't know why the socket shorted, if it *was* wet then perhaps I > could plug it in again, but I am very doubtful that this would be a good > idea. Should I just be thinking of replacing the socket? Many "IEC sockets" are more than just sockets, and incorporate EMI suppression components as well. The euphemism becomes "power entry module" instead of "socket". The EMI suppression components (especially capacitors) in them are specced for AC line voltage applications and UL rated such, but they still let out their magic smoke every so often :-). Even if it's just a socket, some debris can get in there during storage, you plug it in, the debris trips a fuse and vaporizes, and all you're left with is a charred socket. Tim.

13 years

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test-drb March 2011