test-drb

test-drb@ccmp.vtda.org

101090 discussions

by michael.99.thompson＠gmail.com

> > From: Jerry Wright > Sent: Friday, February 06, 2015 8:54 PM > Subject: RA-81 issues > > I have a rack full of RA81's, all Pass Rom base self test. If I try to > spin > up one of the drives, It will start to spin up and then just stop. There > are > no front panel lights that come on or codes on the terminal screen. all 3 > drives do the same. > > These are not connected to a controller, and the manual does not say this > is need. > > The forth one has no drive and the motor seems to turn hard, is there a > brake > on the motor ??? > > - what I'm I missing here > Thanks Jerry > I have seen two common problems problems with RA-81 drives. Failure of the motor start capacitor, and failure of the optical sensor on the bottom of the HDA for spindle speed. With both failures the drive will start to spin-up, and then spin-down. You can connect a serial terminal emulator to the DB25 diag connector. Then you can run internal diagnostics and get the fault codes. The RICM has several RA-81 drives, all with failed optical sensors. -- Michael Thompson

11 years, 6 months

11/23 clock issue

by jnc＠mercury.lcs.mit.edu

> From: Brent Hilpert >> Well, try removing W1 to isolate the output of the xtal oscillator E15 >> from inverter input pin E4.4. Sigh, the crystal output is dead as a doornail. Total flat-line. Guess I'm going to have to find a new one... I actually think there's an open in there, because the input to the buffer inverter stays at +2V, whether the crystal is connected or not. If there was some sort of internal short in the crystal taking its output to ground, I'd have expected it to pull the inverter's input down. > TP4 looks to be an 'input' test point, rather than an output. The > pull-down resistor value (150 or 180 ohms) has been selected such that > it is low enough to allow enough current to flow through the tri-state > control input E4.1 to pull it low normally, but high enough to allow > one to connect TP4 high, to enter tri-state Ah, got it. (I tended to assume test points were outputs, but I need to remember that they may be inputs.) > What the point of going to tri-state is, is not clear, considering that > W1 is there for an external clock. A conjecture is there may have been > some external test fixture that tri-stated it for some sort of > synchronous single-step clocking. Yeah, but couldn't they have lifted the W1 jumper, and fed their test clock in that way? Eh, not important. > Could also check the V reading on the open E4.4 input. See above - +2V is a floating TTL input, ISTR? > From: Holm Tiffe > Hmm, may be since his hints are standard debugging technique and you > aren't really familiar with debugging?? I cheerfully admit to being primarily a software person. But I have been debugging broken hardware off and on for 30+ years - although not as a principal occupation, of course. I think it's more just that my mind does not do hardware intuitively (the more-so, the further one gets from the ideal - aka digital at the design level - to real hardware) - I have to think about it. > You don't ned no pullup for +5. All open TTL inputs are reading High > w/o any pullup. That's why all those boards use pullups on unused inputs that need to be 1, right? :-) But you're probably correct for a quick test. Noel

11 years, 6 months

seeking quality tape recorder

by dave＠661.org

I'm looking for a decent quality portable tape recorder. I do want recording ability so I can make new tapes for my C64 among other purposes. I was about to purchase an Ion Tape Express Plus, but was told by Silent700 in #classiccmp that his imposes an abnoxious throbbing noise to the audio. Does anyone have any different experiences with that unit? Can you recommend something good other than the Ion one? -- David Griffith dave at 661.org A: Because it fouls the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?

11 years, 6 months

Stupid AC wiring question (220-ish Volts...)

by jnc＠mercury.lcs.mit.edu

> From: Josh Dersch > Luckily heavy items can be wheeled on a hand-cart around to the back of > the house, where there's direct access to the basement; no tricky > stairs to deal with. O lucky man! My basement is only stairs-accessible (although one of them is an outside stairs, which is a big help), which led to an extremely annoying incident recently. (This has nothing to do with wiring, but your comment poked a hot-button...) I already had one 11/84, which was donated to me by a fellow aficionado of PDP-11's out in Wisconsin. When I got it here, I was trying to work out how to get it all (CPU cabinet, TU80 cabinet, RA81 cabinet [no drives], and 2 RA81's [separate]) into the basement (the only feasible place to put it in our establishment). I wound up building a ramp out of 2x10's on the outside stairs, and using a block+tackle to lower the units down that into the basement. Worked pretty well, actually - got the whole works down by myself in a couple of hours. So I got another 11/84 system (yeah, yeah, I know) which was in Fornicalia, and had to have it shipped. I originally tried to ship it freight (hey, the units are on wheels, and I didn't care if it got dinged a bit through not being packaged), but when they found out it wasn't palletized, I had to go 'white glove' (at twice the cost). But the good part was 'at least' with WG you get 'inside delivery'. So I'm figuring, good, they'll help me get it into the basement. Nothing doing. I showed them the units in the basement (so they'd know I had experience doing it), they looked at the ramp, and they called their company and then flat-out refused to have anything to do with the process. They claimed they thought it was 'dangerous'. I suspect their real motivation was i) it was raining lightly (which is another irritating thing, they were orignally scheduled to deliver on a day when it was supposed to be good weather, and they begged to move the delivery up, and I told them about the weather, but they were insistent, so I agreed - big mistake, I should have dug in my heels), and ii) they were in a hurry (see previous about wanting to deliver a day early) and wanted to hit the road ASAP. So anyway, we stuck it all in the garage to wait for a day it wasn't raining (hey, if I had to do it all myself, why do it in the rain?), and then my wife and I (she's 4' 10", and all of like 90 lbs) got it into the basement in a couple of hours, no problem. But two big, burly moving guys (I'm 6'0", 200 lbs, and they were a lot bigger than me) thought it was too much for them. To add final insult to injury, the moving company refused to offer any partial refund for not providing the 'inside delivery' they had been paid (a lot!) for! In addition to all the above, it took them 6 weeks to get the stuff here from California. Now, admittedly, Christmas and New Year's were in there, but... Anyway, I would highly recommend having nothing to do with this company; it was an outfit called UKAY. I've dealt with a number of crappy shippers, but these guys were The Shipping Company From Hell. Tell everyone you know about them. Noel

11 years, 6 months

It's time to restore the 11/45 - progress!

by jacob.ritorto＠gmail.com

Hey everyone, making some progress here -- thanks for all the tips so far! Most of the power regulators are fine, but both H745 regulators seem to be toast. Only getting -1.2 volts; should be -15 and they squeal angrily when I turn the pot. The surplus shops seem to want $200 for one, so that's not an option for me. How does one repair such a beast? thx jake P.S. Also, the main H742s are sagging just a little, but I didn't see an adjustment on them to bring them up. Anyone know where to look?

11 years, 6 months

11/23 clock issue

by jnc＠mercury.lcs.mit.edu

> From: Tothwolf >> Sigh, the crystal output is dead as a doornail. Total flat-line. Guess >> I'm going to have to find a new one... > Does it have to be exactly 13MHz for the system to function correctly? > I have some Fox brand 13.824MHz oscillators Actually, they are exactly 13.824MHz on the 11/23, too. Must be a standard speed... > in my parts cabinets that were leftovers from something back in the mid > 90s (probably modem R&D). Oh, this may be totally fantastic. I spent a chunk of time today looking for a replacement, and so far, no luck. So you may really be a life-saver. A generic search for 13.824MHz crystals turned up a whole bunch of SMD parts, and a few of what I think are actual crystals (two leads), but none of those self-contained DIP oscillator units. I have a couple of 11/23 cards, and although the DIP oscillators on them are >from a number of different manufacturers, they all have the same number on them: "18-12131-00", which must be some standard part number. So I tried looking for that, and all I found were a couple of those part-finder services. So, just for grins, I asked three of them for quotes. Only one replied, and they couldn't find them. So if you've got some of the DIP oscillator units, that'd be a life-saver. I'll contact you off-list to work out the logistics? Thanks! Noel

11 years, 6 months

Radio Shack

by marc.verdiell＠gmail.com

You are so absolutely right, you should have been their marketing director and they'd still be around. People still like to build things just the same! They completely missed the Maker movement, the computer mod stuff, the switch to the web. Also too many stores, too small. The stuff they had in there lately was an appalling mish-mash of uninteresting random stuff. No need to read the news, you could so clearly see that the company management was so totally lost and aimless by just visiting a store. Here in the Valley, Fry's Electronics took over, and then made it so much better. Fry's is where you stop at lunch time, for amateur or professional stuff alike, and get an instant replacement for your fried LM7805. It also keeps our company electronics lab and fab and IT alive. And you can get an espresso at the same time, and a pack of sugar loaded cookies if you are a late night programmer. And a concert on a full size Steinway while you are picking up your capacitor. Let's not forget the best of it, being chased around by the totally incompetent sales person that will convince you that SATA and USB are one and the same thing. Trying to lose him by walking progressively faster. Man, they can walk fast too, these are trained professionals. And for the grand finale, being stripped searched going out the door. How is that for the ultimate nerd store experience! Love it all. The Fry brothers are geniuses. Marc >fahimi wrote: > >RadioShack had it essentially right in the 2014 Super Bowl commercial - the 80s called and they did want their store back. What they screwed up was thinking that meant >the old store had to go and be replaced with the current monstrosity. >RadioShack should have brought back the store of the 1980s and updated it items like cheap cables, Raspberry Pi kits, etc. I.E. hobbyist and do it yourself stuff. Yes, they >still would have to close a number of locations (do you really need a ratshack on every corner?) but what would have been left behind would have thrived...

11 years, 6 months

Xerox 4050/4090 print controllers

by microfilm＠microfilm.kscoxmail.com

I'm doing some cleaning and purging around my shop, and I have a collection of Xerox 4050 and 4090 printers and parts, plus the controllers for these beasts. Is there any interest at all in this equipment? I have to get rid of it, soon, but don't want to simply scrap it if there's someone interested in such niche equipment. The CPU itself is a DJC11, 11/70 on a chip. Other peripherals include a Bus & Tag online interface boardset, graphics processor options (I have one seat of each of the two different options that exist, but the system can only handle one at a time), memory boards, FDDC2 floppy controller (contains an Intel 8086, plus a set of Western Digital chips), a board dedicated to print controller to print engine communications, a hard disk interface (up to four MFM disks, in pairs. Originally had two Fujitsu 56MB disks, later replaced with Seagate drives). The terminal for the system is either a Lear-Siegler ADM-3A, or a Link Technologies terminal in ADM-3A mode, both with minor keyboard modifications. (I have several of these terminals on hand.) Barring interest here, the whole lot will be salvaged and the chips sold off. Keep in mind, this stuff is big. The individual interface boards are slightly larger than a hex-height Unibus board. The card cage for the system is about 24" wide, 18" deep, and 30" tall. The complete controller cabinet, with 9T tape drive, is over 5 feet tall, 3 feet wide, and 2 feet deep. I also have other equipment and supplies (8" and 5.25" floppies, new in sealed packages, for example) to move. Everything is located in Wichita, Kansas. --Shaun Microfilm Services, Inc.

11 years, 6 months

What is this Concurrent Computer Corporation machine?

by pontus＠update.uu.se

Hi My employer has over the years ported our main product to more platforms than I can count. I took inventory of our storage the other day and one machine has left me clueless: The Concurrent Computer Corporation machine: http://www.update.uu.se/~pontus/slask/jobb_vind/DSC_0081.thumb.jpg http://www.update.uu.se/~pontus/slask/jobb_vind/DSC_0082.thumb.jpg http://www.update.uu.se/~pontus/slask/jobb_vind/DSC_0083.thumb.jpg As you see it is one rack with a medium sized computer in it. From the internet and co-workers I've learned that it has either a MIPS or 68k processor and runs a unix version called RTU, for Real Time Unix. CCC was initially Interdata, later Perkin Elmer and then spun off into CCC. Has any cctalk-reader experience with this system? Anything would be interesting to learn. This machine might become available in one way or another later this year. And since I believe it was made in Brittain I've pondered asking TNMOC if they want it. Finally, check the content of the directory above for some more Unix history. Kind Regards, Pontus.

11 years, 6 months

Pdp11/23+ EPROM upgrade

by roeapeterson＠gmail.com

I want to update the EPROMs on my 11/23+, which currently has 2716s. I'm going to need 64k chips, and I understand 2764s won't work on this board. What are my replacement options? I have a fairly capable programmer, it can probably handle anything with 64k capacity. Thanks.

11 years, 6 months

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