I believe so, although I have a spray can of what claims to be 99+% propan-2-ol that I use for head cleaning. True story (although I am ashamed to admit it). I was sorting out a Commodore 8250LP (slimline model, double sided drives). And I could not get a reliable read signal. I checked all the components in the head amplifier, the head switching diodes, the head select signals, and so on. I then remembered to clean the heads. Worked fine after that... -tony

Oh, where to start? I've got dozens of such stories where I've been silly. Perhaps this will adversely affect my reputation here, on the other hand I am man enough to admit I'm an idiot, so here goes... I once spend hours at school figuring out why a tape recorder appeared dead. No motor, no valve heater glow, etc. No outputs from the mains transformer. I can't remember how many tests I did before I bothered to unscrew the mains plug and check the fuse (UK 13A mains plugs have a cartridge fuse inside). It was mising. Not blown, but removed. A new fuse got the machine going again. And I spent a very long time (as in several days) sorting out a PDP11/45 that would crash in strange ways after about an hour's running. I was naive in those days and actually tried board-swapping. This made matters worse as the replacement boards were a different revision and there was a backplane modification (an extra clock signal IIRC) that you had to do. Battled through the prints and did that, still no better. After spending hours with boards on the extender card, checking signals, etc, I finally thought to check the PSU. The +5V line to tbe memory (at least) was sitting at 4.2V. Out came the screwdriver and I tweaked the preset on the regulator. No more problems (even with the original CPU boards). Not a silly fault, but a silly thing to do was the time I had a malfunctioning -15V regulator brick in the same machine. I put that on an extender cable (this isn't an offficial DEC thing, but I have a cable with an 8 pin mate-n-lock plug on one end and a socket on the other for working on such bricks). I was trying to figure out why it was giving no output into a minimal load and very foolishly I disabled the overcurrent trip. Alas the reason it was giving no output was that the crowbar was firing. With no overcurrent trip, the crowbar blew just about every transistor on the PCB (and finally the fuse). The flash was spectacular.... Then there was the RK05 that would spin down during major disk activity. When the head was stepping all over the disk, the thing would retract the heads, and de-energise the spindle relay. Then it would start up again and reload the heads. I spent quite a bit of time looking at the logic (and this time I did check the PSU rails, all fine) before I thought to check the interlock signal. It was being de-asserted. Now that comes from 2 microswitches in series, one detects that the door is closed, one detects there's a pack in place. No, both swithces were fine, but some idiot (not me) had cut one of the wires between them and just twisted the ends together and bound them with insulting tape. Soldering that properly cured the problem. More stories when some others have owned up, I guess :-) -tony

Well, let's see. ---- There was the time I was working on mains wiring (helping my parents with their house) and we had something - an outlet box, I think - to work on. We wanted to flip the breaker for that circuit before working on it, but for some reason we weren't sure which circuit it was on. I said something like "well, let's find out", stuck a screwdriver in the corner of the box (metal boxes, properly grounded) and leaned it over to touch the hot wire. It worked, in that it flipped the correct breaker. But I was idiot enough to be looking right at it as I did this. When I could see again, I found that the screwdriver had a semicircular piece chewed out of its shaft, about halfway through, and the room smelled of vapourized metal - steel and copper, presumably. I've never taken that drastic an approach to flipping a breaker since, and don't expect to unless something fairly precious is at stake (say, someone is being electrocuted, that's about the level of severity that could lead me to crowbar a mains circuit). As far as I know, the screwdriver is still in service. (It was last time I had occasion to work around that house, which was years ago.) ---- Then there was the time I was trying to debug a problem with a packet-filtering firewall. The packets just weren't getting through. I stared at the rules, my boss (himself a sharp geek) stared at the rules, one of the owners stared at the rules (the company is owned by two people, the founders - a geek and a businessman), the person who did most of the firewall stuff stared at the rules, and then someone else, who didn't do diddly with firewalls in general, said something like "um, aren't *those* supposed to be over *here*?". Sure enough, the rules were (liberally paraphrased) pass from EXTERNAL to INTERNAL port PORT1 pass from EXTERNAL to INTERNAL port PORT2 pass from EXTERNAL to INTERNAL port PORT3 pass from EXTERNAL to INTERNAL port PORT4 pass from INTERNAL to EXTERNAL port PORT1 pass from INTERNAL to EXTERNAL port PORT2 pass from INTERNAL to EXTERNAL port PORT3 pass from INTERNAL to EXTERNAL port PORT4 and needed to be pass from EXTERNAL to INTERNAL port PORT1 pass from EXTERNAL to INTERNAL port PORT2 pass from EXTERNAL to INTERNAL port PORT3 pass from EXTERNAL to INTERNAL port PORT4 pass from INTERNAL port PORT1 to EXTERNAL pass from INTERNAL port PORT2 to EXTERNAL pass from INTERNAL port PORT3 to EXTERNAL pass from INTERNAL port PORT4 to EXTERNAL I've rarely had that duh! a moment. (At least I had some company.) /~\ The ASCII der Mouse \ / Ribbon Campaign X Against HTML mouse(a)rodents.montreal.qc.ca / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B

At 02:49 01/07/2004, der Mouse wrote: This reminds me.. Some years back, I was doing a complete re-wire on a friends house. They had just moved in, and the previous occupant had been a bit of a DIY nut. I suppose I should have been warned by the "clock point" being bare (thin, multi-strand) wires hanging out of a wall, connected to mains electricity by twisting the other ends around bared cables of the 30A ring-main under the floorboards above. Anyway, it was early evening, but quite dark. I was taking out the old sockets in the kitchen in order to connect up new ones to new cables in the same spots. I'd pulled out every fuse and breaker in the house, except for the dedicated 45A (at 240V) circuit to the cooker - this had a standard main outlet integrated into the cooker isolator switch (pretty standard in older UK installations) , to which I had attached a lamp, to give me chance to work on. Anyway, working my way around the kitchen, I opened up the last socket, snipped off the old cable, and BANG. And the light went out... I was a little shocked (emotionally, not electrically) but obviously not a much so as my friend's wife who had at that moment been stood in the doorway watching. I got a quiet, totally terrified "Are you all right?" Suicidal idiot beforehand had only gone and wired a standard 13A outlet direct into a 45A cooker circuit rather than as a spur off another 13A socket that was actually nearer! It melted a whopping hole in my best cutters, but the insulated handles were good and I never felt a thing. Rob

On Thu, 01 Jul 2004 07:04:45 -0400 "Joe R." <rigdonj(a)cfl.rr.com> wrote: ... and after checking the breaker, get out a volt meter to check if it was the right breaker... An other story: A colleague was screwing in a new "DIAZED" fuse into a breaker panel. BANG! Parts of the fuse flew acros the workshop, a cloud of smoke came out of the panel and all lights where out. We had to replace two big 63 A "NH" fuses that where in front of that breaker panel. "NH" fuses need a _lot_ overcurrent to blow that fast. At close inspection of the breaker panel we saw traces of a wire that had shortend two of the three phases (400 V) and ground. The wire was vaporized. -- tsch??, Jochen Homepage: http://www.unixag-kl.fh-kl.de/~jkunz/

At 11:49 PM 7/1/04 +0100, you wrote: I had a similar experience when I worked in the hospital. One of the things that I was responsible for was repairs to the TVs in all the patients rooms. We once had a call about a dead TV in one room. We went there and checked it and it worked fine but the patient and nurses swore that it hadn't been working before. We couldn't find anything wrong so we left. A hour or so later we got a similar call from the room next door to the first caller. We went and checked and sure enough it was completely dead. Then just on a hunch we went next door and checked the first TV again. It was turned off so we turned it on. When we did, the one of the second room also came on! Both TVs were back to back on a common wall. After playing with them a bit we found that if either set was off it turned of both TVs. Hmmm. We finally found an open line in the wall but it still connected the two sets together however they were now in series so when you turned either one off they both went off! The surprising thing was that both sets were operating off of half their normal voltage but both worked perfectly. Joe

Rumor has it that Tony Duell may have mentioned these words: If he hasn't yet... :-/ Nor would I... in fact, even a simple thing like "locking the store at nite" is triple- and quadruple-checked each nite, and I've been known to get offended when someone *doesn't* double-check my work. ;-) Now here's *my* brainfart for the week: My RadioShack multimeter (computerized mongothingy with RS-232 & everything) decided it didn't want to measure voltage anymore. It did everything else fine[1] so I decided I was gonna have a hand at tearing the thing apart to see what the heck is going on. (It's probably one of three things I own that I've not yet taken apart yet.) So I took it *all* the way apart. Every screw in it was out, things in 20 pieces, didn't bother to mark the alignment of the selector wheel internally, so I had to put it back together twice to get that mapped out where it should be, finally got it realigned & back together, went to test it, and it still didn't work. So, then I think: Waitaminit, dumbass! That outlet that the wallwart is plugged into is a bit flakey, maybe there's no voltage to measure! So I grab a standard alkaline cell, and yea, I get 1.5 volts. So I test a *known working* 12v wallwart - still nothing. Odd... then I say to myself... Self: When's the last time you changed the battery in this darned thing??? I replaced the 9v battery, and everything worked fine![2] Did I feel stupid? Yea... but I got over it quickly, as I was happy it was working again -- and now I know what the innards of the thing look like, in case the next time the problems not so simple... Laterz, Roger "Merch" Merchberger [1] including measuring resistance, which is usually the first thing to go on a low battery condition... [2] And Tony says you can never fix anything right by just partswapping... ;^> -- Roger "Merch" Merchberger | JC: "Like those people in Celeronville!" sysadmin, Iceberg Computers | Me: "Don't you mean Silicon Valley???" zmerch(a)30below.com | JC: "Yea, that's the place!" | JC == Jeremy Christian

Ok, I've done something stupid. Really stupid. I'm almost afraid to post this, because you all will think I am stupid. I lost the 1,x password to my RSTS/E 9 system. I picked a strong password, wrote it on a piece of paper, and put it on my desk. I strongly suspect that it became part of a drawing one of my children did, you know, this is me, this is you, this is the house, and the chimney, that's your password. Anyway, my PDP is a just-pretend simh type PDP (because it would be divorce court if I installed a real one in my house...) and I have it all set up the way I like it, with custom scripts and Dungeon and Adventure, so that people can play these games on the internet via a bbs front end. Each user gets their own account... so they can save their games... ... it took a while to make this work. I'd rather not have to set it up again. Is there any way to hack into my own box to recover my own password, or is it time to mount the install "tapes" and start all over again? Damn! Mark "But Schindler is bueno! Senior Burns is El Diablo!" -------------------------------------------------------------- Website - http://www.retrobbs.org Tradewars - telnet tradewars.retrobbs.org BBS - http://bbs.retrobbs.org:8000 IRC - irc.retrobbs.org #main WIKI - http://www.tpoh.org/cgi-bin/tpoh-wiki

That gets me into 1,2, and I can run money from [0,9], but it doesn't seem to matter if I tell money to print passwords or not, I still don't get passwords printing... Doesn't the system have to store the 1,2 password someplace so it can log into the account at startup? Thanks! Mark "But Schindler is bueno! Senior Burns is El Diablo!" -------------------------------------------------------------- Website - http://www.retrobbs.org Tradewars - telnet tradewars.retrobbs.org BBS - http://bbs.retrobbs.org:8000 IRC - irc.retrobbs.org #main WIKI - http://www.tpoh.org/cgi-bin/tpoh-wiki ----- Original Message ----- From: "Ashley Carder" <wacarder(a)usit.net> To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk(a)classiccmp.org> Sent: Wednesday, July 07, 2004 12:36 PM Subject: RE: I'm stupider than you!! RSTS/E question password, divorce the people password,

Ashley> If you're able to get into 1,2 you can do whatever you want. Ashley> I don't know what kinds of changes happened from v7 to v9, Ashley> but you should be able to do anything you need to do if Ashley> you're on 1,2 (except POKE, which you can only do from 1,1). Ashley> For example, if you can break the startup sequence and get a Ashley> READY prompt while logged into 1,2, you can do Ashley> UT CHANGE [1,2] xxxxxx Ashley> where xxxxxx is the new password for 1,2. Unless $MONEY was Ashley> changed between v7 and v9, you should also be able to print Ashley> passwords from 1,2. Ashley> The passwords are stored in account [1,1], also known as the Ashley> MFD (master file directory). $MONEY uses SYS() function call Ashley> SYS(CHR$(6%)+CHR$(14%)) to retrieve the accounting info, Ashley> including passwords, from the MFD. You could also write a Ashley> program to open [1,1] as a file and get all this info Ashley> yourself, bypassing the SYS() call and going directly to the Ashley> MFD. Of course, all of this would require you to be logged Ashley> on as a privileged user (1,*). All this is quite different as of V9.0. For one thing, there's a GFD (group file directory), and account attributes are stored there. Second, MONEY is history as is UTILTY -- these things changed to DCL command like "set account" or "set password". Finally, though it wasn't used all that widely, V9.0 and later have multiple privilege flags very much like what VMS has (somewhat better, in my opinion, but I'm biased...). The defaults are like they were before, but you can make 1,* accounts that are not privileged, or non-1,* accounts that are. Or you can have accounts that are somewhat privileged. For example, you can set up an account that can do backups -- but not restores, so that user can read files but not change files. paul

Looks like things are different in V9 than they were in V6/V7. Perhaps I need to update my knowledge base beyond V6. - A ----- Original Message ----- From: "Paul Koning" <pkoning(a)equallogic.com> To: <cctalk(a)classiccmp.org> Sent: Wednesday, July 07, 2004 9:53 AM Subject: Re: I'm stupider than you!! RSTS/E question

Hmm, compared to my answer, this sounds like the good DEC guy answer vs. the evil 1978 teenage hacker answer. Back then they didn't call us hackers. I have a 1977 or 78 article that refers to us as "computerniks". Perhaps I'll scan the article and post it where folks can read it. It's pretty interesting and starts off something like "Beware - Computerniks at Work!". Ashley ----- Original Message ----- From: "Paul Koning" <pkoning(a)equallogic.com> To: <cctalk(a)classiccmp.org> Sent: Wednesday, July 07, 2004 9:40 AM Subject: Re: I'm stupider than you!! RSTS/E question

----- Original Message ----- From: "Mark Firestone" <pdp11_70(a)retrobbs.org> To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk(a)classiccmp.org> Sent: Wednesday, July 07, 2004 11:04 AM Subject: Re: I'm stupider than you!! RSTS/E question a I actually think it was much higher than $20k. In 1975, our 11/40 with two RK05s, RSTS/E, a couple VT50s, and an LA36 or two cost over $50k, and that was with a discount from DEC. The list price for that system as described above was $68,000. I am working on recreating a reasonable facsimile of the system described above. I'm constructing a PDP-11 computer center room (heated/cooled) in my shop to house this thing. I have the system up and running on an 11/34 and plan to move it to an 11/40 in a couple 6' racks in the next couple months. I

----- Original Message ----- From: "Bert Thomas" <bert(a)brothom.nl> To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk(a)classiccmp.org> Sent: Saturday, July 03, 2004 10:40 AM Subject: Re: I'm so stupid... Was: Head Cleaners You did this with high voltage? Shorting out 480VAC by hand with a small cable is a good way to shit your pants at the very least.

Yes, it is that. But I still don't like it, and I suspect it's hard on the breaker. If I had to do such a "deliberate trip" today, I'd probably do something like plug in an iron and a hair dryer - high-draw devices that together exceed the breaker's trip point, but not as drastically so as a dead short. /~\ The ASCII der Mouse \ / Ribbon Campaign X Against HTML mouse(a)rodents.montreal.qc.ca / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B

In message <40E28759.F80CAB32(a)cs.ubc.ca> Brent Hilpert <hilpert(a)cs.ubc.ca> wrote: Lesson #1: Before doing ANYTHING else, get a multimeter and check ALL the power supply voltages. If the power supply reads good, go get the schematics and an oscilloscope :) I think I've still got a power supply somewhere that has a flaky 5V regulator. Sometimes the regulator starts up fine, then runs for hours. Other times it just sits there dead - strangely enough, drumming one's fingers on the casing usually gets the regulator to start. I'll fix the dry joint on the PCB when my Farnell L30B bench PSU dies. Speaking of which, does anyone have a service manual for the Farnell L30B power supply? One of these days, I'll build a custom power supply. At the very least, the L30B needs its switches, one of the meters and all of the potentiometers replacing. Oh, and I need to find two self-tapping (?) screws to hold the side panels on. Bleagh. Later. -- Phil. | Acorn Risc PC600 Mk3, SA202, 64MB, 6GB, philpem(a)dsl.pipex.com | ViewFinder, 10BaseT Ethernet, 2-slice, http://www.philpem.dsl.pipex.com/ | 48xCD, ARCINv6c IDE, SCSI ... Growing old is mandatory; growing up is optional!!

Actaully I'm more likely to suggest yoy resolder that darn dry joint, and go over others in the area. Preferably before soemthing in the sense circuit goes open and the output jumps to 15V or whatever! -tony

At 10:59 PM 6/28/04, you wrote: FYI, the Safeway grocery stores around here (Maryland, USA) sell 99% isopropyl rubbing alcohol. That and cotton-tip swabs do a pretty good job of cleaning tape and floppy drive heads. Cheers, Dan www.decodesystems.com/wanted.html

In message <200406290259.TAA13244(a)floodgap.com> Cameron Kaiser <spectre(a)floodgap.com> wrote: Servisol IPA-170 seems to work quite well for all sorts of things - I've used it to remove thermal compound from heatsinks, clean tape heads, remove solder flux, that sort of thing. I think it's about 90% pure, "electronics grade" or something like that. Maplin Electronics sell it for about ?5 per 400ml aerosol can. Later. -- Phil. | Acorn Risc PC600 Mk3, SA202, 64MB, 6GB, philpem(a)dsl.pipex.com | ViewFinder, 10BaseT Ethernet, 2-slice, http://www.philpem.dsl.pipex.com/ | 48xCD, ARCINv6c IDE, SCSI ... In nuclear warfare all men are cremated equal.