test-drb April 2020

test-drb@ccmp.vtda.org

142 participants
114 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, 9 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

Pdp11/05 boot media

by doug＠doughq.com

Hi everybody I'm the proud owner of a PDP11/05 system with a couple of 8" floppy drives. I believe they are likely to be RX01s. Does anybody on the list have some boot media that they could provide. I understand that the controller can't format the disks so I'm in a frustrating state where I don't know where to start. Doug Jackson Canberra Australia.

4 years, 4 months

Great, my VT52 is shot.

by cz＠alembic.crystel.com

Wonderful: A few weeks ago I forgot to turn off my VT52 and left it running for a day or two. Now the screen is filled with snow and it looks like the text is all over the place horozontally. Any tips or thoughts on where to start looking to fix? The keyboard seems to be working as does the RS232 input (the snow on the screen changes when the pdp11 talks to it) Thanks! Chris

4 years, 5 months

Facit N4000 Schematic

by ard.p850ug1＠gmail.com

>From time to time there are posts here about the Facit N4000 paper tape punch/reader unit. The one that looks like a Facit 4070 with a tape reader on the front (in fact the punch mechanism is much the same as that in the 4070). I have reverse-engineered mine and traced out the schematics. Of course it's one of my hand-drawn ones but I think it's mostly legible. If anyone wants it I am happy to send out a copy (but as ever I'd rather send it out once and have somebody else pass it on) -tony

4 years, 5 months

Wanted, Papertape Reader for Archiving Tapes

by billdegnan＠gmail.com

Hi - COVID project.... I have been attempting to read some old Honeywell DDP-516 papertapes using the OP-80A or Teletype reader but it's inefficient and I don't want to damage the tapes. Does anyone have a reliable papertape reader for sale, or recommend one currently out there on Ebay, for the purpose of archiving papertapes of any kind safely and reliably. I have a reasonable budget. I have a lot of tapes that need to be archived, so I'd want one that I can interface with to capture into TAP files or what I would call a raw dump listing of the data in 8-bit Hex. MITS, SWTPc, Z80 stuf, PDP 8, PDP 11, Honeywell, etc. End goal is to load tapes into simH, PDPGUI, Altair/S-100, textfiles to display tapes. I want to be able to view the tape as it would be in Intel or Motorola format, etc. What does everyone else do? For example: S1131C102C20DEBD19217E167DBD185FD6259626A3 S1131C209B27C900D70297037E167DBD1999DE282C S1131C30DF2C9C022742D6029603902DD22C2A1C1C S1131C40D62C962DBD015ADF2CD6029603BD015A1F S1131C509C2C2724A600BD02270820F4D602960354 S1131C60BD015ADF2ED62C962DBD015A9C2E270875 S1131C70A600BD02270820F47E167DDEDBDF027E8F S1071C80167D0000C9 S9030000FC Thanks for any advice. Bill

4 years, 5 months

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test-drb April 2020