test-drb March 2020

test-drb@ccmp.vtda.org

137 participants
81 discussions

H7821 power supply in MicroVAX 3100, SCSI disk enclosures and others

by cctalk＠beyondthepale.ie

The recent discussion on BSC protocol prompted me to dig out my Microvax 3100 with DSH32 synchronous serial interface. It had been idle in storage for several years and it wouldn't power up, only giving a brief flash on the diagnostic LEDs and a quick twitch of the fans. There was a slight smell, like the stale air that comes out of a deflating tyre. I took out the H7821 power supply and found that five identical brown 1800uF 25V electrolytic capacitors on the output side had leaked. The SCSI disk enclosure where the machine's system disk lives required several power cycles to get it to run at all and it died as soon as the disk tried to spin up. It turned out to also contain a H7821 power supply which had a similar issue with the same five brown capacitors, although not as extensive as in the main unit. I found a second disk enclosure which had seen little use and grabbed the power supply out of that to put in the MicroVAX. It worked well enough to test with but there was a ring of goo around the bottom of one of the brown capacitors which was worst affected in the other units. Time to order a batch of replacement capacitors and figure out what else has been damaged. While it is not the worst I have seen, access to these power supplies for repairs is quite difficult and it is really difficult to debug them safely while they are running with the cover off :-( If anyone has anything with H7821 power supplies in them, I suggest checking on these capacitors. If anything with these power supplies is in storage, I suggest ensuring it is stored the normal way up as this should limit the ability of the goo to escape and spread around the power supply. And there I was thought I was being safe enough by removing the nicad battery packs some years ago... Regards, Peter Coghlan.

2 years, 8 months

PDP-11/05 microcode dump?

by jnc＠mercury.lcs.mit.edu

> From: Mattis Lind > Thanks Noel for sorting this out. Eh, de nada. But thank you. >> I wonder if the ucode in the two versions is identical? The uROM chip >> numbers should give it, (if they are the same on both versions, albeit >> in different locations on the board), but I have yet to check. Does >> anyone happen to know? OK, so the situation here is pretty complicated. To start with / make things worse, that CPU uses lots of PROMs. Lots and lots and lots and lots of PROMs. For the data paths board (M7260), both major versions appear to contain the same PROMs (going by the DEC part numbers), but the chip location (Exx) numbers are all different. For the control board (M7261), the C, E ('early' version) and F ('late' version) etch revisions each contain mostly the same PROMs, but apparently with slight differences between the sets of PROMs in each (as reflected in different DEC part numbers). For details see: http://gunkies.org/wiki/PDP-11/05#Control_PROMs to which I have just added all the gory details. As to getting the contents of all of them dumped in machine-readable form - oi vey! >> on the earlier version (prints for that version are in the GT40 prints >> online It turns out that I have hard-copy prints for the "C" etch revision of the M7261, which do not yet appear to be online; the GT40 prints have the "E" etch revision. I will scan the pages for that revision of the board, and put them up 'soon'. (I'm not doing the whole print set, it's about 1" thick, and most of them are for other things anyway, like MM11-L memory, etc.) Noel

3 years, 3 months

ISO earl TI DSP kits

by aek＠bitsavers.org

CHM doesn't seem to have much early DSP stuff in the collection Does anyone have any of the TMS32010/20/30 or C1x/2x/3x hw/sw kicking around? Other than the docs I've scanned there doesn't seem to be much on the web either.

3 years, 10 months

Font for DEC indicator panels

by jnc＠mercury.lcs.mit.edu

> From: Toby Thain > To get closer I'd need better images of the panels. Hi, I borrowed a DEC inlay from someone (a KA10 CPU bay) and scanned a chunk of it (as much as I could fit into my A4 scanner :-) at 200 dpi: http://ana-3.lcs.mit.edu/~jnc/tech/jpg/KACPUPanel.jpg I have a TC08 inlay, but it's currently being used in my QSIC display (until we can get the RKV11-F/RPV11-D inlay done :-), and I didn't want to yank it out. As far as I can tell, it's the same font on the two of them. > the closest I know of off the top of my head is Akzidenz Grotesk. The Akzidenz Grotesk Medium is indeed very, very close (other than the zero). Do you happen to know if that font available for use in non-commercial settings? Thanks! Noel

3 years, 11 months

Pro 350 Print Set

by robert.jarratt＠ntlworld.com

Manx lists MP-01394-00 as the Field Maintenance Print Set for the DEC Professional 350. I can't find this online and I was wondering if anyone has a scan of it by any chance? Thanks Rob

4 years

Monitors FTGH

by a.carlini＠ntlworld.com

The following four monitors are available free for pickup in the UK (OX17 postcode). All appear clean but are untested. All are believed to have been functional when stored but that was ~2002/2003-ish. Microvitec Cub. Seems to be in its original box. DEC VRT19-D3. Vision Master Pro 17. DEC VRC21-W3. Obviously with the current restrictions on movement these cannot be picked up, but they need to be gone soon after the restrictions are over. Expressions of interest offlist please. Antonio -- Antonio Carlini antonio at acarlini.com

4 years, 2 months

World's most frustrating FTGH giveaway - Palm Pilot box

by mark.tapley＠swri.org

All, Next to go is a box in which a Palm Pilot was originally sold. The box is in great shape, shrink-wrap intact except where it was sliced just enough to open the top. The manual is in great shape. The registration card is in great shape. The order receipt is in great shape, name of original owner mis-spelled but otherwise apparently correct. The accessories catalog is in great shape. The software on 3 each 3.5? floppies and on CD appears to be in great shape (not test-read yet). The Now Sync accessory software, on 2 more 3.5? floppies, appears to be in great shape. The leatherette protector is in great shape, with its foam insert still inside keeping it shaped for the Palm Pilot. The DE-9 to DB-25 serial port adaptor is in great shape. For Pete?s sake, the screen protector that peeled off the Palm Pilot screen is in great shape, lovingly tucked into the manual. You have probably noticed what is missing. There are no electronics included. No Palm Pilot, no charging/syncing cradle. Grrrr. You probably want this if you picked up the Palm Pilot at ShopGoodwill somewhere, want to re-create that 1997 ?first on the block with a personal digital accessory? feeling and really enjoy going through the accessory paperwork. https://www.shopgoodwill.com/Item/87198940 (but I think that is a different model). Free to a Good Home, preferably one with an actual Palm Pilot. Shipping will be from San Antonio TX, 78254. If as I suspect, nobody interested, headed to the trash. Standard rules, I?ll wait for a week or so, ship to the sender of the first email in my in-box or to Al K if he emails before I ship. - Mark 210-522-6025 office 210-379-4635 cell

4 years, 5 months

Motorola EXORciser M6800 System

by osi.superboard＠gmail.com

Since a few days, my EXORciser Development System is finally able to boot from floppy diskettes. Previous attempts have shown that the Motorola EXORciser M68SFDC1 floppy disk board used has a special modified ROM version. This was probably written for an 8-inch drive, in which the Write protect and Direction signal were inverted. For the sake of simplicity, I have used free inverter on the board to invert the signals accordingly. After adjusting the PLL frequency, reads and writes from the card are now error-free. And all without FDC, only clever programming by Motorola software engineers in the early 76? Originally, the EXORdisk system was a dual drive with two 8 "units. This I have replaced with a double drive of two 5.25 inch units. An Epson and a TEAC, which can be jumpered to 360 rpm. Luckily, 2HD floppy disks are easy to R&W. I also got a GOTEK floppy emulator running, which I can boot from. Thanks to Roland Huisman, Bitsaver has some interesting floppy disks that convert to HFE format work perfectly. This format makes the Gotek drive most reliable. Now to my question. The vintage computer forum at http://www.vcfed.org/forum/archive/index.php/t-44638.html mentioned some interesting manuals. Archive.org has some manuals, Bitsaver does not have manuals about the M6800 development system. If someone already owns scanned manuals to the following list M6800 Basic Interpreter Reference Manual M6800 Macro Assembler reference Manual M68SFDU Exordisk 11/111 Disk `Drive Unit Maintenance Manual M6800 Exorciser 11 User's Guide M6800 Exorciser User's Guide MEX68PP1 PROM Programmer Module Supplement M6800 Exorciser User's Guide I would welcome any feedback or questions --THOMAS

4 years, 5 months

anybody have MOVIE.BYU?

by rdawson16＠hotmail.com

The famous Brigham Young University 3D graphics program, by Dr. Hank Christensen. I am looking for the fortran source, it should be 7 files: DISPLAY SECTION UTILITY TITLE COMPOSE UPDATE MOSAIC Any docs related too. Thanks for letting me beg. Randy

4 years, 5 months

VAXmate PSU

by robert.jarratt＠ntlworld.com

I have posted here a couple of times because I have a failed VAXmate PSU. I have just posted a little bit more information here: https://robs-old-computers.com/2020/03/28/further-analysis-of-the-vaxmate-h7 270-psu-failure/ with some scope traces and a greatly improved schematic. Although the schematic is likely to have errors still. Unfortunately, a stray scope probe ground lead blew the fuse so now I have to wait for a new fuse to arrive before I can continue work. I would really like to know if all the spiking I am seeing is to be expected, and any suggestions why it appears to be detecting an overcurrent? There do not appear to be any shorts on the secondary side, but that could be wrong of course. I don't know if a genuine short anywhere would cause it to trip the SCR quite so quickly (within 20ms of the switching transistor starting to switch). Any thoughts gratefully received. Thanks Rob

4 years, 5 months

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test-drb March 2020