test-drb June 2020

test-drb@ccmp.vtda.org

158 participants
124 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, 11 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, 5 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.

4 years

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

4 years, 1 month

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, 2 months

DECnet/E Y2K bugfix

by paulkoning＠comcast.net

I just made some small changes to the DECnet/E event logger application to fix a Y2K problem. (More precisely, a Y2K.003 problem). https://github.com/pkoning2/decstuff This is for RSTS V10.1. Just drop the new evtlog.tsk into [0,16]. paul

4 years, 4 months

UniSys ClearPath OS/2200 Express?

by Kevin＠RawFedDogs.net

Classic Computer Fans, Technically this isn't a classic OS, but I suspect its lineage goes back far enough to be of interest. Has anyone tried out UniSys ClearPath OS/2200 Express? https://www.UniSys.com/offerings/clearpath-forward/clearpath-forward-produc… I normally don't run Windows at home, but have set up a Windows 7 VM to try it out. It includes a few PDFs, including basic startup and shutdown procedures. I haven't found any intro to OS/2200 type docs yet. If anyone knows of any, please let me know. It looks like it could be an interesting system, if I can ever learn my way around. -- Kevin http://www.RawFedDogs.net http://www.Lassie.xyz http://www.WacoAgilityGroup.org Bruceville, TX What's the definition of a legacy system? One that works! Errare humanum est, ignoscere caninum.

4 years, 4 months

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, 4 months

Ancient transistor ?computer board (Peter Van Peborgh)

by peter＠vanpeborgh.eu

OK, now here are some pics that should be available to everybody. I hope. https://photos.app.goo.gl/h64tye8ecmPHQfJD7 Smells of (early) 1960s transistorized. No helpful marking apart from * "GATE JJ01" on SIDE A. (components). * "C NT OL DATA" on side B (solder traces). Big transistors are Motorola "180376008". Also, any ideas what the "246 636 B" boxes are, they have four legs? A curse on TinyURL and praise to Camiel Vanderhoven. peter

4 years, 5 months

Hp 21mx loader rom set

by grant＠klyball.com

Hi all, i am looking for a loader rom set for my 21mx and does not seem to be around at the usual places, I am hoping to find a leed. Here is what i am in need of. 12992L consisting of 12992-80011 91740-80070 91740-80071 91740-80072 there is a set of 91740 on bit savers but with a suffix of 67-69 ? any help would be appreciated. Thanks Grant

4 years, 5 months

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test-drb June 2020