test-drb July 2005

test-drb@ccmp.vtda.org

257 participants
628 discussions

by ajp166＠bellatlantic.net

> >Subject: Re: VT-131 prints? > From: Ethan Dicks <ethan.dicks at gmail.com> > Date: Sat, 02 Jul 2005 15:25:41 -0500 > To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> > >On 7/2/05, Allison <ajp166 at bellatlantic.net> wrote: >> Common VT1xx part failure. Seemed they made the video board with a >> 50V cap where a 100V cap should be. Huge numbers of them were made >> and failed but amazingly there are still many in use that havent.. Yet. >> It is repairable as it cooks a cap, diode and resistor. > >That sounds like once someone traces down the problem, it belongs in a >FAQ somewhere. > >I haven't had any failures like that, so I guess I'd like to know >more, especially to buy a bag of 100V caps and preemptively fix some >of my terminals (I have stuff ranging from gen-u-ine VT100s, to >VT102s, a VT103, a VT105, a DECmate I, etc., and I don't recall if I >have a VT125 or VT131 or not. > >-ethan All qualify. It's the board in the monitor (display) that is in question. There is a (memory test) 100mf 50V cap and it's subject to more than that (about 70V). It was fixed in production and who knows how many field repairs by board replacement, I once saw a crate of dead boards 4x4x6ft full, and that was a sample. If the cap is replaced with suitable the failure is unlikely. I have several VT1xx and all have been fixed over 10 years ago. Failing boards display height and linearity problems before they fry. Allison

18 years, 10 months

VT-131 prints?

by ajp166＠bellatlantic.net

> >Subject: VT-131 prints? > From: Dennis Boone <drb at msu.edu> > Date: Sat, 02 Jul 2005 00:57:43 -0400 > To: cctech at classiccmp.org > >I have a VT-131 suffering from video circuit problems. The logic >seems to be ok -- does a self test, led dance, emits a normal beep, >and ends with the on-line led lit. The crt filament is glowing. >Key click happens when keys are pressed. No screen display. >I've turned up brightness in set-up, flying blind. Haven't twiddled >the pot yet. So far, I've just taken the lid off, and am looking >into the still-assembled chassis. > >The video board has some very charred-looking spots around the solder >pads of one component (cap? spherical white ceramic-like device with >two stout leads) down and to the right of the brightness adjustment. > >The tech manuals from bitsavers and vt100.net don't give me enough >info to identify the component in question. > >Anyone have prints they'd be willing to scan bits of for me? Or read >off to me by e-mail? Or have "replace this, kid" or "you're screwed" >specific knowledge of this scenario? > >TIA, > >De Common VT1xx part failure. Seemed they made the video board with a 50V cap where a 100V cap should be. Huge numbers of them were made and failed but amazingly there are still many in use that havent.. Yet. It is repairable as it cooks a cap, diode and resistor. The Video board is common to most VT1xx. Mine are deeply burried. Allison

18 years, 10 months

Netcom HV1148 chassis for DEC?

by rigdonj＠cfl.rr.com

I found one of these today. Nice chassis, it's obvioulsly made for DEC cards and has 12 Quad width card slots. However I don't know if it's Omnibus or what. Anybody know? Joe

18 years, 10 months

Does anyone have a Radio Shack Electronics Learning Lab?

by ethan.dicks＠gmail.com

Hi, I picked up an ELL (RS 28-280) at the outlet store. It was cheap because all of the loose parts were missing. I have the base and the books. The PDF file on the RS web site doesn't list things in enough detail to be able to build a list of missing parts. I'm going through the books and trying to tally the required parts, but it's taking hours and I'm likely to make mistakes. Does anyone have one of these and might they have enough time to make a physical inventory? Even a digital picture of the parts spread out on a tabletop would be really helpful. Thanks, -ethan

18 years, 10 months

SASI device <-> PC ?

by julesrichardsonuk＠yahoo.co.uk

Has anyone here successfully interfaced a SASI device to a PC at the hardware level? I've got a few classic systems which use SASI (or not-quite-SCSI) controllers to talk to SASI-ST506 bridge boards and from there to ST506 type drives. As has been documented many times in the past here, an ST506 drive has a pretty tight relationship with its controller, and so hooking up the drive to a different controller (say MFM controller in a PC) causes all sorts of problems when it comes to backup. Hence driving the SASI side of things (and preserving the drive/bridge board relationship) would seem like a sensible move when it came to backing up data. In theory data could then be restored to a replacement drive if/when the original dies via the same method. Presumably inventing a simple SASI board to hang off a PC parallel port (say) is a lot easier than mucking around with the equivalent for floppy drives - or is the data rate still likely too low to cause timeout problems within the bridge board's firmware? I've got several Acorn, Torch and RML machines which use bridge boards and in most cases the tools needed to back up and restore data have long since vanished off the face of the earth (my RML fileserver's a particularly important one as it seems to be the only one left in the world) cheers Jules

18 years, 10 months

SSM V1B Manual request

by dave04a＠dunfield.com

At 07:13 02/07/2005 -0400, you wrote: >All: > > Does anyone have a copy of the Solid State Music V1B video board >manual that they'd be willing to make a scan of (or make a copy of so I can >scan it)? Hi Rich, If by chance you are referring to the SSM VB1B video board... I have the manual available on my site. Go to "S100 cards" near the bottom of my main page, then scroll down to the SSM section, and click the "1.4M PDF" link beside the listing for the VB1B. Regards, Dave -- dave04a (at) Dave Dunfield dunfield (dot) Firmware development services & tools: www.dunfield.com com Collector of vintage computing equipment: http://www.parse.com/~ddunfield/museum/index.html

18 years, 10 months

SSM V1B Manual request

by rcini＠optonline.net

All: Does anyone have a copy of the Solid State Music V1B video board manual that they'd be willing to make a scan of (or make a copy of so I can scan it)? Thanks. Rich Rich Cini Collector of classic computers Build Master for the Altair32 Emulation Project Web site: http://highgate.comm.sfu.ca/~rcini/classiccmp/ /************************************************************/

18 years, 10 months

Problems using VG PROM/RAM in 8800b

by rcini＠optonline.net

All: I want to get the Turnkey Monitor running on my 8800b. I have a VG PROM/RAM board (which has 1k of RAM and an EPROM programmer) and some 2716 EPROMS. I made an adapter so I can use 2716 chips in the 2708 sockets. So far, so good. I configured the board for $C000, no RAM and all other jumpers per the default for the board with the following exceptions: (1) "Use PRESET or POC for power-on/reset jump" The defaultis for the POC signal to be connected to the reset circuitry on the VG PROM board. The other jumper option is to connect PRESET to the reset circuit on the VG PROM board. This is now set for the PRESET line to be connected to the board's POR circuit. I don't have a schematic so I don't know what this is doing exactly. (2) "Phantom generated if power-on/reset" This disables other memory boards on reset so it can respond to the CPU reset jump to location 0 (making the board an auto-start board). I cut this jumper. (3) "Jump to PROM/RAM board if power-on/reset" This causes the board to respond to the CPU jump to location 0 on RESET. I set this jumper to the equivalent of disable. With this configuration, I can't EXAMINE or DEPOSIT to/from any location. When I remove the board, the Altair responds normally, so it definitely is this board. Does anyone have any experience using this board in an Altair (or other non-Vector) system? What's a working configuration for this? Does anyone have a spare generic ROM board I can buy/trade for? Thanks. Rich Rich Cini Collector of classic computers Build Master for the Altair32 Emulation Project Web site: http://highgate.comm.sfu.ca/~rcini/classiccmp/ /************************************************************/

18 years, 10 months

CS/80 disc gceometry

by aek＠bitsavers.org

David Bryan pointed me to page 6-5 of www.hp.com/products1/rte/tech_support/documentation/documentation4/ 92084-90025.pdf which has the following table: model mbytes xfrRat(kbytes) #surf #cyl #secs(256by) # blocks acc time(ms) 7907A 41 600 2/unit 627 64 80,256/unit 44 7908A 16 561 5 370 35 64,750 58 7911A 27 835 3 572 64 109,824 43 7912A 64 835 7 572 64 256,256 43 7914A 132 1000 7 1152 64 516,096 41 7933/35 404 1000 13 1321 92 1,579,916 35 7936 307 1000 7 1396 123 1,202,956 31 7937 571 1000 13 1396 123 2,232,204 31 7941/42 24 625 3 968 32 92,928 48 7945/46 55 625 7 968 32 216,832 48 7957A 81 853 5 1013 63 319,095 42 7957B 81 875 4 1269 63 319,788 28 7958A 130 853 8 1013 63 510,552 42 7958B 152 875 6 1572 63 594,216 28 C2200 335 1840 8 1449 113 1,309,840 27 C2203 670 1840 16 1449 113 2,619,792 27

18 years, 10 months

Old PS/2 Hard Drives

by SUPRDAVE＠aol.com

In a message dated 6/30/2005 12:22:29 AM Eastern Standard Time, chenmel at earthlink.net writes: This past weekend I picked up an old PS/2 machine. It's a Microchannel system, a Model 65sx (I think). The only thing missing in it is the hard drive. It has one of those 3-1/2" drives with the full-length card-edge connectors on it, I think 50 pins wide or so, that provides all connections including power. I would like to get it up and running just to have around as another working system (also got a Compaq Portable III at the same auction for $10 in a leather case!). Any suggestions where I could find such a drive easily? Is this machine's HD interface an ST-506 variant, EISA, or what? --------- 8565 is a 386DX-25 I think with a SCSI controller instead of ESDI that the model 60 used. Take note of what adaptor cards are installed. This machine is a floppy based reference disk instead of using an IML partition so you will need to build a reference disk with all the adf files on it. If parts are needed, I can help with whatever is needed.

18 years, 10 months

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test-drb July 2005