Re: Replacement for a DEC 7474 Chip
On 05/15/22 18:00, cctech-requ...@classiccmp.org wrote: Send cctech mailing list submissions to cct...@classiccmp.org To subscribe or unsubscribe via the World Wide Web, visit http://www.classiccmp.org/mailman/listinfo/cctech or, via email, send a message with subject or body 'help' to cctech-requ...@classiccmp.org You can reach the person managing the list at cctech-ow...@classiccmp.org When replying, please edit your Subject line so it is more specific than "Re: Contents of cctech digest..." Today's Topics: 1. Replacement for a DEC 7474 Chip (Rob Jarratt) 2. Re: Replacement for a DEC 7474 Chip (John Robertson) 3. Re: Replacement for a DEC 7474 Chip (Paul Koning) 4. Re: Replacement for a DEC 7474 Chip (Nigel Johnson Ham) 5. Re: Replacement for a DEC 7474 Chip (ben) 6. Re: Replacement for a DEC 7474 Chip (Chuck Guzis) 7. Re: Replacement for a DEC 7474 Chip (ben) 8. Re: Replacement for a DEC 7474 Chip (dwight) 9. Re: Replacement for a DEC 7474 Chip (Chris Zach) 10. RE: Replacement for a DEC 7474 Chip (Rob Jarratt) 11. Re: Replacement for a DEC 7474 Chip (Eric Smith) 12. Re: Replacement for a DEC 7474 Chip (Eric Smith) 13. Re: Replacement for a DEC 7474 Chip (Chuck Guzis) -- Message: 1 Date: Sat, 14 May 2022 18:11:32 +0100 From: "Rob Jarratt" To: "General Discussion: On-Topic and Off-Topic Posts" Subject: Replacement for a DEC 7474 Chip Message-ID:<007b01d867b5$a8c90f00$fa5b2d00$@ntlworld.com> Content-Type: text/plain; charset="us-ascii" Hello, I have found a bad DEC 7474 chip on my M7133 board. Clearly it is a 7474 D flip flop. The problem is I don't know which modern series would be the best one to replace it with. I am sure I have seen a list somewhere of modern equivalents for some DEC chip numbers, but I can't remember where. If it helps at all, on the PDP 11/24 printset it is E78 on page K6 of the schematic (p157 of the PDF). Picture of the failed chip here: https://rjarratt.files.wordpress.com/2022/05/damaged-dec-7474-4_li.jpg Can anyone tell me what the best modern equivalent is likely to be? Thanks Rob -- Message: 2 Date: Sat, 14 May 2022 10:41:34 -0700 From: John Robertson To: Rob Jarratt via cctalk Subject: Re: Replacement for a DEC 7474 Chip Message-ID: Content-Type: text/plain; charset=UTF-8; format=flowed On 2022/05/14 10:11 a.m., Rob Jarratt via cctalk wrote: Hello, I have found a bad DEC 7474 chip on my M7133 board. Clearly it is a 7474 D flip flop. The problem is I don't know which modern series would be the best one to replace it with. I am sure I have seen a list somewhere of modern equivalents for some DEC chip numbers, but I can't remember where. If it helps at all, on the PDP 11/24 printset it is E78 on page K6 of the schematic (p157 of the PDF). Picture of the failed chip here: https://rjarratt.files.wordpress.com/2022/05/damaged-dec-7474-4_li.jpg Can anyone tell me what the best modern equivalent is likely to be? Thanks Rob You are stuck with using an original 7474 family assuming this is driving other early TTL. 74LS74, and others simply don't have the drive capability to work. You can use 74S74 or 74F74 as they have the same output current, the "S" is Schottky, and the other is "F"aster. I find that https:///unicornelectronics.com is a reliable source of TTL. John :-#)# Original 74 series TTL can still be found, Ebay often, new old stock and other surplus vendors. Would need to take care replacing with later ttl series, as the gate delay, switching times and fanout probably won't match. Always use the original series if you can... Chris
RL02 Tracking (Aaron Jackson)
On 12/22/20 18:00, cctech-requ...@classiccmp.org wrote: Send cctech mailing list submissions to cct...@classiccmp.org To subscribe or unsubscribe via the World Wide Web, visit http://www.classiccmp.org/mailman/listinfo/cctech or, via email, send a message with subject or body 'help' to cctech-requ...@classiccmp.org You can reach the person managing the list at cctech-ow...@classiccmp.org When replying, please edit your Subject line so it is more specific than "Re: Contents of cctech digest..." Today's Topics: 1. RL02 Tracking (Aaron Jackson) 2. Re: RL02 Tracking (Aaron Jackson) 3. Re: RL02 Tracking (Jon Elson) 4. Re: RL02 Tracking (Josh Dersch) 5. Re: RL02 Tracking (Aaron Jackson) 6. Re: tty and video displays (Jules Richardson) 7. Re: Keyboard storage (Guy Sotomayor) 8. Wordperfect 6.0 for DOS (Van Snyder) 9. Re: RL02 Tracking (Noel Chiappa) 10. Keyboard storage (Alan Perry) 11. Re: Keyboard storage (Warner Losh) 12. RE: Keyboard storage (Ali) 13. Re: Keyboard storage (Alan Perry) 14. RE: Keyboard storage (Ali) 15. Re: Keyboard storage (Alan Perry) 16. Re: Keyboard storage (Guy Sotomayor) 17. RE: Keyboard storage (ED SHARPE) 18. Re: RL02 Tracking (Christian Corti) 19. Re: Keyboard storage (Patrik Schindler) 20. Re: RL02 Tracking (Aaron Jackson) 21. Re: RL02 Tracking (Aaron Jackson) 22. Re: Keyboard storage (Alan Perry) 23. Re: Keyboard storage (Bill Degnan) 24. Re: Ouch, but 2 Perqs out. (Why 42? The lists account.) 25. Re: Ouch, but 2 Perqs out. (Why 42? The lists account.) 26. Re: Ouch, but 2 Perqs out. (Tony Duell) 27. Re: Ouch, but 2 Perqs out. (Tony Duell) 28. Re: Ouch, but 2 Perqs out. (Chris Zach) 29. RE: Keyboard storage (Fred Cisin) 30. RE: Keyboard storage (ED SHARPE) -- Message: 1 Date: Mon, 21 Dec 2020 19:08:14 + From: Aaron Jackson To: "cctalk@classiccmp.org" Subject: RL02 Tracking Message-ID:<91bim8vyo2q@mimas.cs.nott.ac.uk> Content-Type: text/plain; charset="iso-8859-1" Hi everyone I've posted a few times over the years about RL02 drives and my difficulty getting them working (no luck so far!). I've spent the past few days working on one of them and have made some progress. The status currently is that the heads will load, and the ready lamp flashes as the heads wobble back and forth very slightly, trying to lock onto the outer servo guard band. Probing TP2 of the read/write module, I can see the S1 servo burst flash (roughly in time with the ready lamp). If I disconnect power to the servo motor, I can manually move the head onto the outer guard band (less than a mm away) and monitoring the position signal (TP15 on the drive logic module) shows this to be close to 0. So, I'm very confused. I've worked through chapter 3 multiple times... - voltage checks - all good - sector transducer output check - all good - sector pulse timing check - all good - read signal amplitude check and adjustment - all good - positioner radial alignment - required some tweeking but is good now - head alignment - looks good to me - spindle runout check - a little noisy but within spec - position signal gain check - looked ok - tachometer ac noise pickup check - this one didnt look so good Supposedly if the main drive motor is bad it will emit noise and cause the tachometer (just a coil of wire on the head carriage) to produce spikes. Mine does look quite noisy but I'm not sure what's causing it. I would expect that if it was picking up noise, I'd be able to detect this with my oscilloscope probe by putting it close to the motor, but I can't. Any ideas? Also, thanks to pjustice on irc who suggested checking the spindle grounding button. Mine is very worn out but I've been able to apply some pressure to it from the under side which reduces the resistance of the spindle to ground, from 400 ohm to 0 ohm. This didn't make the situation any better though. Still, the situation over all is much better now than it was last time I looked at the drive (over two years ago now I think). Previously the heads would attempt to load and then the fault lamp would come on immediately. At least now it's trying to lock onto a track. I have the same results with two cartridges (which is all I have!). If anyone has any ideas I'd love to hear them! Aaron Aaron, One thing I would check is the motor bearings. What happens on electro mechanical assemblies left in store for years is that ball bearing grease lube dries out and hardens, resulting in lumpy rotation and increased friction that can be detected by rotating the spindle by hand. RLxx series drives were very reliable typically, but the head movement assy is pretty cheap and cheerful. Converting spindle to linear movement, minimum parts count, dc brush brush motor, means that all the bits need to be smooth in operation, with no stiction anywhere in it's
Re: NEC NEAX IVS2 PBX with NEAXMAIL AD-8 - hard drive clone, issues
The way I would do that is to use a Linux / unix machine and one of the cheap ebay usb to ide adapters, then use dd to image the whole drive to a file. That should copy block, including the boot block and partition table. Use the reverse process to image the file back to another drive... Chris
Disabling SCSI parity checking to dump disk on ACB4000, MFM-SCSI adapter?
On 09/24/20 18:00, cctech-requ...@classiccmp.org wrote: Disabling SCSI parity checking to dump disk on ACB4000 MFM-SCSI adapter? I have a sun 3 system with acb4000 and suspect the protocol was not fully sorted in that time frame. They can be fussy about what they will talk to, ime. Would lend a hand if you are in the uk, but otherwise, if you have an early Sparc system, I would try that, as it would probably still support the older controllers. Sparcstation 1 or 2 + Sunos probably has the required entries in the format utility, format.dat file. An early pci or isa Adaptec card might be worth trying as well, under Suse 11.4 or similar, as that has a good disk utility... Chris
Re: cctech Digest, Vol 65, Issue 3
On 02/11/20 18:00, cctech-requ...@classiccmp.org wrote: Send cctech mailing list submissions to cct...@classiccmp.org To subscribe or unsubscribe via the World Wide Web, visit http://www.classiccmp.org/mailman/listinfo/cctech or, via email, send a message with subject or body 'help' to cctech-requ...@classiccmp.org You can reach the person managing the list at cctech-ow...@classiccmp.org When replying, please edit your Subject line so it is more specific than "Re: Contents of cctech digest..." Today's Topics: 1. looking for: fairchild model 8200 manual (Adrian Stoness) 2. Opening a MicroVAX 2000 (Antonio Carlini) 3. RD53 failure modes (Carlos E Murillo-Sanchez) 4. PC3XC manual? (Paul Koning) 5. Re: Old IBM magnetic media (cct...@emailtoilet.com) 6. Looking for info - Computer Extension systems WE-VM8E8 board (Bob Smith) 7. Re: RD53 failure modes (Fred Cisin) 8. IBM Type 31 Alphabetical Duplicating Keypunch available, Seattle area (Josh Dersch) 9. Re: IBM Type 31 Alphabetical Duplicating Keypunch available, Seattle area (William Donzelli) 10. Re: IBM Type 31 Alphabetical Duplicating Keypunch available, Seattle area (Tony Aiuto) 11. Re: IBM Type 31 Alphabetical Duplicating Keypunch available, Seattle area (Lyle Bickley) 12. Making use of Panda dist TOPS20 (David Griffith) 13. Re: Making use of Panda dist TOPS20 (Ethan Dicks) 14. Re: Opening a MicroVAX 2000 (Josh Dersch) -- Message: 1 Date: Sat, 8 Feb 2020 18:50:25 -0600 From: Adrian Stoness To: "General Discussion: On-Topic and Off-Topic Posts" Subject: looking for: fairchild model 8200 manual Message-ID: Content-Type: text/plain; charset="UTF-8" trying to find a manual for a fairchild universal counter timer model 8200 circa 1968? got one i found like to see if i can get it working for the rack. can only find this sales catilog from 68 https://l.facebook.com/l.php?u=https%3A%2F%2Farchive.org%2Fdetails%2FTNM_Instruments_catalog_multimeters_and_various_o_20171025_0048%2Fpage%2Fn11%2Fmode%2F2up%2Fsearch%2Ffairchild%2Bmodel%2B8200%3Fq%3Dfairchild%2520model%25208200=AT2SbCVHC4Bf1LBj-UBDAeFgyB_79Ov-tSEHfbJYlfJ3BBA0SrVHyqlY85S9NLZq2AzAf9K0D9OweDdNRockMT0TxmKJYL5HHV8odxS6lp9Tek0jo0PhWZA7Lb6i9Oaf4-0 https://l.facebook.com/l.php?u=https%3A%2F%2Fdrive.google.com%2Fopen%3Fid%3D1IZDamqqNJP8a8ilZWALSNg_na2hZqKr3%26fbclid%3DIwAR3LJf3o-4y_xSALVXNzHBaFeBRBP_oDjr_CviGm0TZxUTR14aKtXwPH1y8=AT2SbCVHC4Bf1LBj-UBDAeFgyB_79Ov-tSEHfbJYlfJ3BBA0SrVHyqlY85S9NLZq2AzAf9K0D9OweDdNRockMT0TxmKJYL5HHV8odxS6lp9Tek0jo0PhWZA7Lb6i9Oaf4-0 https://l.facebook.com/l.php?u=https%3A%2F%2Fdrive.google.com%2Fopen%3Fid%3D1aAnHIUHDdc_YjqkWy5z8rc_WsUQ0p0KN%26fbclid%3DIwAR2XLjHzEujXBgJS0-iAt2yJXBbDhCv9LjVPsyJpk423nsDjLxIQL4g-Kz8=AT2SbCVHC4Bf1LBj-UBDAeFgyB_79Ov-tSEHfbJYlfJ3BBA0SrVHyqlY85S9NLZq2AzAf9K0D9OweDdNRockMT0TxmKJYL5HHV8odxS6lp9Tek0jo0PhWZA7Lb6i9Oaf4-0 hasnt been powered up since prolly 1986 has a tag on it about channel B not working. was found in a rack sitting out in 40below temps prolly been sitting there for 20-30yrs in a storage shed the guts are realy clean on it so proly has potential to get working again. -- Message: 2 Date: Mon, 10 Feb 2020 11:17:03 + From: Antonio Carlini To: "General Discussion: On-Topic Posts" Subject: Opening a MicroVAX 2000 Message-ID:<7d2cf42b-03c1-b514-d8aa-b85c0af83...@ntlworld.com> Content-Type: text/plain; charset=utf-8; format=flowed I'm trying to non-destructively open up a MicroVAX 2000. I've removed the bottom "dressing" section (which holds some of the I/O connectors)? but the next step isn't obvious. None of the manuals I have cover dismantling and the net doesn't have an IPB or similar available. Other people have managed to get inside (I can see their results) so I must be missing something obvious ... Thanks. Antonio Antonio, From memory, the 2000 case covers are really tight and may need a bit of leverage to remove, assuming all the screws have been removed. Very close fitting rfi shields + several years of light corrosion etc... Regards, Chris
Re: Strange third party board in PDP-11/45
Message: 1 Date: Sun, 22 Jul 2018 09:22:25 -0400 (EDT) From: j...@mercury.lcs.mit.edu (Noel Chiappa) To: cctalk@classiccmp.org Cc: j...@mercury.lcs.mit.edu Subject: Re: Strange third party board in PDP-11/45 Message-ID: <20180722132225.49a0b18c...@mercury.lcs.mit.edu> > From: Paul Birkel > ABLE Computer Technology. Their first product was PN 10001 ... the > A.C.T. Univerter This board is not shown in any of the Able brochures we have: http://bitsavers.trailing-edge.com/pdf/able/brochures/ However, Able info is _very_ thin on the ground, now... Noel There was a Univerter and Qniverter (sp) which were used to translate from unibus to qbus.Very useful boards and used one to translate from vax730, vms 4.3 to a qbus expansion box, so I could use an RQDX3 and RD53 as vms boot. Just set up the dipswitches and it works automagically at power on. May have docs somewhere, but not sure where... Chris
