test-drb July 2005

test-drb@ccmp.vtda.org

257 participants
628 discussions

Replace roller rubber on HP 9825 tape drive

by dwight.elvey＠amd.com

>From: ard at p850ug1.demon.co.uk > >> >> > Hi Tony >> > I'm proposing an experiment for you since I know that >> > you are the type that would actually try it. >> >> I am going to try this, although probably not tonight... >> >> However, even if it does bahave as you suggest, it still doesn't explain >> _why_... I will have to think about this some more... > >Sorry to follow up my own message, but I spent last night thinking about >it, and I think I now understand it. > >The things that are important are (a) the belt is elastic and therefore >stretches, and (b) the drage from the spools means that the tension in >the belt is not the same all the way round. There is more tension in the >belt on the takeup side than on the supply side. > >Supppos that a certain length of belt has gone past the supply spool (and >thus wound off that length of tape). As it goes round the takeup spool the >belt will be stretched a little more, so it will move the surface of that >spool by more than the amount that the surface of the supply spool was >moved. It will try to wind more tape onto the takeup spool, thus >tensioning the tape. > >For obvious reasons this effect is small. It helps to have the tape >fairly well tensioned before using the cartridge. If you're reassembling >a defective one, I'd tension the tape as much as possible by hand. > >If you could make a cartridge with the belt round the outside, and with >the drive roller possitioned far enough forward to let the bead get in >contact with the tape (inside the loop formed by the belt), it wouldn't >work. There'd be more movement on the supply side, the tape would get >ever more slack. > >-tony > Hi That is why I mentioned to Joe that you need to pull on the supply side tape a little to get it to take up the slack. That is what I recall doing when I replaced the bad roller. I don't recall how I got the last little bit of slack out of the tape. I remember holding onto it with a ChemWipe to keep my finger oils off the tape but that only works until is gets close. One still needs to suck in the last bit of slack before putting it into a machine. Like I said, it was counter intuitive to pull on the supply side to get the take-up side to suck in the tape but that is what I recall. It wasn't until now, years later, that I thought about how it could work. Thinking about how the Bernoulli's principle worked with a elastic band helped to figure it out. The more stretched band at the take-up has to have a higher surface speed. It should be fun to confirm by the spool experiment :) It was a fun thought experiment anyway. Dwight

19 years, 6 months

Discrete Component FlipFlop

by marvin＠rain.org

> >Marvin Johnston wrote: > >> Our annual Bazaar was held today with all the leftover stuff now at my > >> house ... briefly! In searching through the stuff this afternoon, I > >> found several boards that I couldn't identify. One is labeled "FlipFlop" > >> and the other "Inverter". I put up a picture of both sides of the > >> FlipFlop at: http://www.rain.org/~marvin/flipflop.jpg > I also noted that I don't see any 3 lead devices? I doubt > it was for tubes so where are the transistors? > Dwight The transistors are inside the plastic pieces at each end of the board. The flipflop board has one on each side, and the inverter has two on each side. The plastic pieces are riveted to the board, so I can't easily see the transistor ID. I think I've checked almost everything now, and there are three flipflop boards and two inverters.

19 years, 6 months

Any 3B2/310 owners in here?

by dwight.elvey＠amd.com

Hi Bernd If you should find one, I'd be willing to help you get CP/M-8000 running on it. Dwight >From: "Bernd Kopriva" <bernd at kopriva.de> > >Hi Jim, >was there a "C 900" included ? .... >... i'm still looking for such a beast ! > >Ciao Bernd > >On Mon, 11 Jul 2005 01:08:46 -0500, Jim Brain wrote: > >>This weekend, while picking up a large donation of Commodore equipment >>(~2000 pounds, the truck springs bottomed out :-), I also secured a >>3B2/310. Alas, I'm not at all up on this type of machine. Google >>brought up some information, but I'd appreciate any personal anecdotes >>or information. >> >>Jim >> >>P.S. In other news, the CBM donation was well worth picking up. A >>prototype Commodore 65 was included. >> >> >>-- >>Jim Brain, Brain Innovations >>brain at jbrain.com http://www.jbrain.com >>Dabbling in WWW, Embedded Systems, Old CBM computers, and Good Times! >> >> >> >> > > >Bernd Kopriva Phone: ++49-7195-179452 >Weilerstr. 24 E-Mail: bernd at kopriva.de >D-71397 Leutenbach >Germany > > >

19 years, 6 months

Discrete Component FlipFlop

by dwight.elvey＠amd.com

>From: "woodelf" <bfranchuk at jetnet.ab.ca> > >Marvin Johnston wrote: >> Our annual Bazaar was held today with all the leftover stuff now at my >> house ... briefly! In searching through the stuff this afternoon, I >> found several boards that I couldn't identify. One is labeled "FlipFlop" >> and the other "Inverter". I put up a picture of both sides of the >> FlipFlop at: >> >It will only take another 2513 more years to collect the whole computer. >Off Hand the logo on the Flip/flop is you best bet to find who made it. >That is not dec and IBM. > Hi I also noted that I don't see any 3 lead devices? I doubt it was for tubes so where are the transistors? Dwight

19 years, 6 months

Apple 1 on ebay - Well, WAS it an Apple 1??

by dwight.elvey＠amd.com

>From: "Vintage Computer Festival" <vcf at siconic.com> > >On Sat, 9 Jul 2005, John Napier wrote: > >> But, I mean, just in terms of getting a response at all, it's harder >> for someone to speak up if they are already judged a "moron". >> I'd love to hear what they actually got, without calling them names >> if it turns out to be an apple //e or whatever. >> >> - Joe >> >> (we've all fucked up at least once. I bought a Bentley for 20K that I >> sold for 6K. e.g.) > >That's not a fuck-up, that's reality. You made the choice knowing >everything. There's no analogy whatsoever to what happened here, which is >someone buying a wooden box with a keyboard on speculation (driven by the >seller's fraud through omission) that it was something else. > >If it does end up being an Apple-1 I will eat my first born. > Hi There is a real good chance that the wood box computer wasn't even found in the same collection as the Apple. the seller just put the two together for effect. Dwight

19 years, 6 months

Replace roller rubber on HP 9825 tape drive

by vcf＠siconic.com

I'm trying to repair the tape drive in an HP 9825. The roller has melted (no surprise there). It seems like I could just get a bit of silicon tubing or something that has the same diameter and guage as the existing roller. I know this has been discussed before but I can't find any specific messages (by the way, the CC archive search is broken, Jay). Can anyone provide any tips or guidance so I don't have to re-learn mistakes already made? Any tips for cleaning off the existing material? Isopropyl alcohol? Any thoughts of using heatshrink tubing and applying multiple layers until it has the same thickness as the original roller? Thanks for any help. This will be a candidate for adding to the knowledge base once I've successfully replaced the roller. -- Sellam Ismail Vintage Computer Festival ------------------------------------------------------------------------------ International Man of Intrigue and Danger http://www.vintage.org [ Old computing resources for business || Buy/Sell/Trade Vintage Computers ] [ and academia at www.VintageTech.com || at http://marketplace.vintage.org ]

19 years, 6 months

repairing cracked plastic

by compoobah＠valleyimplants.com

I have had good luck (depends on plastic-see below) with MEK (Methyl-Ethyl-Ketone), works the same way as the dichloromethane, can be acquired in most hardware shops. It doesn't work very well on some of the "alloy" plastics (GE Cyclolloy? mix of polycarbonate and ABS. Superglue doesn't even work here-the plastic disintegrates into a mealy mush). Fortunately, that seems to be only used in newer Suns and PCs. Drywaller's Fiberglass tape might be a good strong inorganic reinforcer, or I sometimes use interfacing (a semi-fabric thing) when I repair books- might work for computers too. In books, it seems to grab the glue better than standard woven fabric. -Scott Quinn

19 years, 6 months

Apple cable ?

by rimmer＠xs4all.nl

Can anyone tell me what kind of Apple cables these are ? http://www.oldcomputercollection.com/applekabel.jpg Thanks! Stefan.

19 years, 6 months

WAS .... PDP-11/23+ and rx-02 drives, need help!!!

by g-wright＠worldnet.att.net

Thanks to everyone that took the time to respond. As the story goes Henk (My 11/60 buddy) was right on the money with the the board location. I started out there a Year ago but in time made the mistake of not following my notes and installing the board below the disk controller. The other problems where, none of the Blank "DEC labeled" disks will Format even now, but will work on a CPM machine. The drive looks for something very quickly and errors even in single density mode. I did get some new "DEC labeled" disks to work now. The other issues where that 2 out of the 3 sets of RK-02's where Bad and only 1 of my RT11 disks will boot. So I had a large hole to dig myself out of. All are working now. I just went through 10 sets of RK-02s and only got 4 going. Most have bad boards. It seems that the lower board is the worst with 5 bad. Most of these came from a Damp location. Someone else had them stored in a barn. I have tested these by swapping the boards into the working machines and using the boards from the working machines in the test machines. On the Hardware side, after cleaning and lubing all seemed to be OK. At least they could boot from either drive. Anyone had any luck repairing the boards ???? What effect does the moisture have on the boards ???? They where not outside just damp air. I have cleaned them with board cleaner and checked the switches for operation. Some of the IC pins are getting rusty. Are the IC's sealed very well or can moisture get in the chips Just think, I still have TE-11/16's and RL-01/02's to get going. Before MY 11/60's. Thanks again Jerry Jerry Wright JLC inc. ....>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi, I'm trying to get one of my 11-23's going and finally got around to setting up a TU58 emulator. got it to boot RT-11 and now trying to get a RX-02 working. I have 3 controllers and 3 sets of RX-02's. All do the same thing. The just seems to not be able to find track 1 or Home or ??? The heads just keep going from home to maybe the first tack and back. The heads do load and the system tries quit a few times then pauses and tries again. It then errors on drive failure or read error directory not found, size function failed depends what I ask it to do. I have tried all of the boards and drives. all or them seem to do the same thing. I do not know how good the drives are but can't believe there all bad. I have recheck the switches in the RX-02 and the Jumpers on the cards. Cleaned the drives. tried different disks. Is there some kind of compatibility issue that i do not know about. Or do I have 6 dead drives. The system is a Micro PDP 11, 8 slot Rack mount, with 1 M8189 1123+ 1 M8067 KB 256k Memory 1 M8639 YA MFM rx50 controller 1 M8029 RX-02 controller in this order. Everything else seems to work. I added the floppy card but the rest original. Thanks, Jerry Jerry Wright JLC inc. ------------------------------ M

19 years, 6 months

cctalk Digest, Vol 23, Issue 17

by mtapley＠swri.edu

At 12:00 -0500 7/7/05, Cameron Kaiser wrote: > > http://www.malevole.com/mv/misc/killerquiz/ > >w00t, I got 7/10! Ha ha! I will slaughter you all, I mean, I did well. ....with a nice Chianti... 7/10 here too. -- - Mark 210-522-6025, temporary cell 240-375-2995

19 years, 6 months

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test-drb July 2005