Overland T490 cartridge tape drive and autoloader

2021-12-09 Thread Peter Coghlan via cctalk
Many years ago, a friend gave me an Overland T490 tape drive which has some kind of autoloader attached which takes ten tapes. I was told it came out of a Tandem system. The tapes are square cartridges similar but different to a DEC TK50. I can't find very much information about the drive on the

RE: Source for replacement caps in H744 regulators

2022-01-06 Thread Peter Coghlan via cctalk
> >> -Original Message- >> From: cctalk On Behalf Of Christian Corti >> via cctalk >> Sent: 06 January 2022 10:02 >> To: General Discussion: On-Topic and Off-Topic Posts >> >> Subject: Re: Source for replacement caps in H744 regulators >> >> On Thu, 6 Jan 2022, r...@jarratt.me.uk wrote

H7821 power supply in MicroVAX 3100, SCSI disk enclosures and others

2022-01-08 Thread Peter Coghlan via cctalk
Speaking of problems with DEC power supplies... Some time ago I posted about problems with five 1800uF capacitors in multiple H7821 power supplies leaking electrolyte, particularly when the machines are stored in the wrong orientation. One of my MicroVAX 3100 machines has a slightly different loo

DEC 3000/600 Alphaserver problems

2022-01-11 Thread Peter Coghlan via cctalk
I have a rackmount DEC 3000/600 Alphaserver containing a H7816-BA power supply which doesn't work. As I mentioned before, this power supply is a real pig to work on. I also have two tabletop DEC 3000/600 Alphaservers which contain H7816-AA power supplies which are similar but not identical. The

Re: DEC 3000/600 Alphaserver problems

2022-01-11 Thread Peter Coghlan via cctalk
On Tue, 11 Jan 2022 13:57:07 -0600, Jon Elson wrote: On 1/11/22 10:40 AM, Peter Coghlan via cctalk wrote: I have a rackmount DEC 3000/600 Alphaserver containing a H7816-BA power supply which doesn't work. As I mentioned before, this power supply is a real pig to work on. I also hav

RE: DEC 3000/600 Alphaserver problems

2022-01-11 Thread Peter Coghlan via cctalk
isn't being shorted but it is working to help you > reveal the bad component. In case the power supply has any inductors that > might suffer from a shorted tant, I would remove and use my own bench supply > as described above. > > Good luck! > > 73 Eugene W2HX > Su

Re: DEC 3000/600 Alphaserver problems

2022-01-12 Thread Peter Coghlan via cctalk
On Wed, 12 Jan 2022 at 11:02:47 -0600 Jon Elson via cctalk wrote: On 1/11/22 5:17 PM, Peter Coghlan via cctalk wrote: Thanks Jon. Here is a badly focused picture of the suspect components: http://www.beyondthepale.ie/cctech/p1010198.jpg WOW, I don't know what those are!  They look lik

Re: DEC 3000/600 Alphaserver problems

2022-01-12 Thread Peter Coghlan via cctalk
On Wed, 12 Jan 2022 at 11:02:47 -0600 Jon Elson wrote: On 1/11/22 5:17 PM, Peter Coghlan via cctalk wrote: Thanks Jon. Here is a badly focused picture of the suspect components: http://www.beyondthepale.ie/cctech/p1010198.jpg WOW, I don't know what those are!  They look like big ce

Re: DEC 3000/600 Alphaserver problems

2022-01-12 Thread Peter Coghlan via cctalk
On Wed, 12 Jan 2022 at 19:30:58 +, Peter Coghlan via cctalk wrote: On Wed, 12 Jan 2022 at 11:02:47 -0600 Jon Elson via cctalk wrote: On 1/11/22 5:17 PM, Peter Coghlan via cctalk wrote: Thanks Jon. Here is a badly focused picture of the suspect components: http://www.beyondthepale.ie

Re: DEC 3000/600 Alphaserver problems

2022-01-12 Thread Peter Coghlan via cctalk
On Wed, 12 Jan 2022 at 17:28:33 -0600 Richard Schauer via cctalk wrote: On Wed, 12 Jan 2022, Peter Coghlan via cctalk wrote: They do have spikes of solder sticking out from the positive ends Yes, those are tantalum caps. The "hat" as I've always called it marks the posit

Re: AOL diskettes

2022-01-18 Thread Peter Coghlan via cctalk
On Tue, 18 Jan 2022 at 13:38:32 -0700, Adam Thornton via cctalk wrote: > > I wish I'd kept some. I had some AOL CDs from slightly later that made > decent coasters for decades. Although I guess with the shutter, the floppy > wouldn't really have made a very good coaster. > I can only conclude yo

Re: IBM 6731 Diskette Module

2022-01-19 Thread Peter Coghlan via cctalk
On Wed, 19 Jan 2022 at 04:06:59 -0800, D. Resor via cctalk wrote: > > There was also a 5.25" diskette which was nicknamed "IPL" for "initial > program load", and an interface board which was installed into the > typewriter and was referred to as the "IBM Typewriter Modularity Option". > Hi Don, A

Re: AOL diskettes

2022-01-19 Thread Peter Coghlan via cctalk
On Wed, 19 Jan 2022 at 12:00:33 +0100, Peter Corlett via cctalk wrote: >On Tue, Jan 18, 2022 at 04:47:36PM -0700, Grant Taylor via cctalk wrote: >> On 1/18/22 2:21 PM, Peter Coghlan via cctalk wrote: >>> https://www.thisiswhyimbroke.com/floppy-disk-table/ >> I like it!

More switchmode power supply grief - Cisco IGS router

2022-02-03 Thread Peter Coghlan via cctalk
I have a Cisco IGS router which hasn't worked for a long time. When I was last using it several years ago, it occasionally crashed and restarted. This turned out to be due to a poor contact on a connection in the cable going from the output of the power supply to the main board. I cleaned the con

Re: More switchmode power supply grief - Cisco IGS router

2022-02-05 Thread Peter Coghlan via cctalk
"Maciej W. Rozycki" wrote: > On Thu, 3 Feb 2022, Peter Coghlan via cctalk wrote: > >> Today I finally managed to check it out. The ceramic F4A mains input fuse >> beside the power switch on the back panel had blown. When I opened it up, >> I found a POWER-ONE

Re: More switchmode power supply grief - Cisco IGS router

2022-02-05 Thread Peter Coghlan via cctalk
Phil Blundell wrote: > > Does that PSU have a PWM controller IC, or is it built entirely from > discretes? > If there is an IC driving the chopper transistor then you may be able to get > some clues about the likely characteristics of the transistor from the IC > datasheet. > It's all discretes.

Re: More switchmode power supply grief - Cisco IGS router

2022-02-05 Thread Peter Coghlan via cctalk
d, I don't know if > there was a lower profile model). > > Thanks, > Jonathan > > --- Original Message --- > > On Saturday, February 5th, 2022 at 09:17, Phil Blundell via cctalk > wrote: > > > On Thu, Feb 03, 2022 at 06:06:10PM +, Peter Coghlan via ccta

Re: More switchmode power supply grief - Cisco IGS router

2022-02-06 Thread Peter Coghlan via cctalk
"Maciej W. Rozycki" wrote: >On Sat, 5 Feb 2022, Peter Coghlan via cctalk wrote: > > > > This PSU seems to have been used across various Cisco devices and I had > > > one fail several years ago in a WS-C1202 Ethernet/FDDI switch, also > > > having >

Re: Rack Discussion Continued - Slide lubricant

2022-03-04 Thread Peter Coghlan via cctalk
I have several difficult slides in my H960 rack. What is the best lubricant for the slides? I was wondering if graphite would work better than oil due to the fact that it won't pick up dirt and dust. Powdered graphite for lubricating locks? I wouldn't like to have conductive stuff like th

Re: AlphaServer 2100s available

2022-04-15 Thread Peter Coghlan via cctalk
It's worth what someone is willing to pay for it and this will vary widely. I got one for EUR 20 in 2006. I didn't think this was a bargain because I was under the impression I was getting it for free before I travelled to pick it up. The previous owner had no further use for it and needed the

Re: AlphaServer 2100s available

2022-04-15 Thread Peter Coghlan via cctalk
hether the price that a local recycler is asking for one (which was around $100) is fair. On 4/15/22 3:30 AM, Peter Coghlan via cctalk wrote: It's worth what someone is willing to pay for it and this will vary widely. I got one for EUR 20 in 2006.  I didn't think this was a bargain

Re: Advice on Desoldering an IC

2022-04-16 Thread Peter Coghlan via cctalk
I had to desolder a fairly large number of 14/16 pin ICs from a two layer PCB recently. I had an basic soldering iron and a spring loaded solder sucker thing. I also had some wick but never having had good results with this, I decided not to bother trying it this time. I was aware of the idea of

H7816-BA power supply (Was Re: H7821 power supply in MicroVAX 3100, SCSI disk enclosures and others)

2022-04-26 Thread Peter Coghlan via cctalk
A few months ago, I mentioned a faulty H7816-BA power supply in a rackmount DEC 3000/600 Alphaserver. I finally got around to looking at it again recently. I hoped I had an identical working power supply to compare it to but I didn't. It turns out what I had is two working H7816-AA power supplie

DEC H7822 power supply

2022-05-01 Thread Peter Coghlan via cctalk
I'm having a lot of problems with DEC power supplies. Newly failed ones are getting added to the end of the queue quicker than I am managing to pop fixed ones off the top of the queue :-( The latest one to give trouble is a H7822 in a MicroVAX 3100. This machine apparantly never got deployed for

Re: DEC H7822 power supply

2022-05-02 Thread Peter Coghlan via cctalk
I wrote: > > At least the H7822 does not seem to suffer from the leaky capacitor problem > like the H7821 does. > Well, it's made a liar of me already. While checking over my previous work replacing the zener diode to make sure I didn't break something else, my eye was drawn to a ring of sticky b

Re: DEC H7822 power supply

2022-05-03 Thread Peter Coghlan via cctalk
"Maciej W. Rozycki" wrote: >On Mon, 2 May 2022, Peter Coghlan via cctalk wrote: > >> Thankfully, it doesn't seem to have been there long and didn't get a chance >> to spread around the board. Bizarrely this capacitor has it's legs pointing >> up

Re: DEC H7822 power supply

2022-05-03 Thread Peter Coghlan via cctalk
"Maciej W. Rozycki" wrote: >On Mon, 2 May 2022, Peter Coghlan via cctalk wrote: > >> Thankfully, it doesn't seem to have been there long and didn't get a chance >> to spread around the board. Bizarrely this capacitor has it's legs pointing >> up

Re: DEC H7822 power supply

2022-05-03 Thread Peter Coghlan via cctalk
Hi Maciej, Thanks for your input. "Maciej W. Rozycki" wrote: > > Lying on a side would also permit leaking, I've seen an H7821 damaged in > storage that way. Gravity only helps with the leads up. > I have lots of H7821s that were on their side for a few years and leaked a lot but I also have H

Re: DEC H7822 power supply

2022-05-05 Thread Peter Coghlan via cctalk
Hi Maciej, > > Right, my notes indicate Nichicon PL parts might be problematic too, e.g. > one at 4700uF/10V on 5V output of the H7826 PSU. > What is H7826 used in? I don't think I have any of those. > > I can confirm now Nichicon PF 47uF/35V parts to be the source of an issue > with my Bel P

Re: DEC H7822 power supply

2022-05-09 Thread Peter Coghlan via cctalk
Hi Maciej, > > > > > What is H7826 used in? I don't think I have any of those. > > DECstation 5000/1xx systems and TURBOchannel Extender boxes. Not sure if > anything else. > Ok. I have VAXStation/MicroVAX and Alpha systems but no DECStations so that explains why I haven't seen them. > > >

Re: DEC H7822 power supply

2022-05-09 Thread Peter Coghlan via cctalk
Tony Duell wrote: > On Sun, May 8, 2022 at 1:02 PM Maciej W. Rozycki via cctalk > wrote: > > > In the H7821 it's -9Vdc return pairing with -9Vdc supplied on the yellow > > wire (an isolated circuit). Pin numbers 14 & 13. Try measuring voltage > > across the suspicious connections as any referen

Re: DEC H7822 power supply

2022-05-10 Thread Peter Coghlan via cctalk
Peter Coghlan wrote: > Tony Duell wrote: > > On Sun, May 8, 2022 at 1:02 PM Maciej W. Rozycki via cctalk > > wrote: > > > > > In the H7821 it's -9Vdc return pairing with -9Vdc supplied on the yellow > > > wire (an isolated circuit). Pin numbers 14 & 13. Try measuring voltage > > > across the su

Re: DEC H7822 power supply

2022-05-11 Thread Peter Coghlan via cctalk
Christian Corti via cctalk wrote: On Tue, 10 May 2022, Peter Coghlan wrote: > Ahead of the 78M09 is another TO220 package marked D45H8 which seems to > be a transistor. Then I am completely lost. I can't find the rectifier That TO220 part would be the rectifier. It either has two legs (simple

Re: Cctalk subscription disabled

2022-05-11 Thread Peter Coghlan via cctalk
I recall discussion of this issue on the mailing list a number of times in the past, often involving more heat than light. I'd suggest searching the mailing list archives if this were possible. I had a quick look just now but I was only able to find this: http://www.classiccmp.org/pipermail/ccta

Re: DEC H7822 power supply

2022-05-11 Thread Peter Coghlan via cctalk
” as rectification > changes AC to DC ? > > > Sent from my iPhone > >> On May 11, 2022, at 01:36, Peter Coghlan via cctalk >> wrote: >> >> The ripple on the rectified 5V and 12V supplies gets transformed into an >> isolated AC source for the 9V supply. >

Re: DEC H7822 power supply

2022-05-12 Thread Peter Coghlan via cctalk
Maciej W. Rozycki wrote: > On Thu, 12 May 2022, Peter Coghlan via cctalk wrote: > >> Anyway, the good news is that I think I have found the source of the >> problem. One of the capacitors used to filter the (DC?, pulsed DC?, >> rippled DC?, biased AC?) supply to the 9V r

RE: DEC H7822 power supply

2022-05-12 Thread Peter Coghlan via cctalk
> > Wayne: AC DC terminology has been well documented since the 1800's. > Don't try to reinvent the terms or no one will know what you are talking > about. > I answered a few things below... > They didn't have switch mode power supplies in the 1800s. Terms like AC and DC as understood back th

Re: DEC H7822 power supply

2022-05-12 Thread Peter Coghlan via cctalk
Toby Thain via cctalk wrote: On 2022-05-11 7:02 p.m., Peter Coghlan via cctalk wrote: Given the normal usage that has evolved for the terms DC and AC rather than their dictionary definitions, I would suggest that the current that gets passed by a rectifier has both a DC component and an AC

Re: DEC H7822 power supply

2022-05-12 Thread Peter Coghlan via cctalk
Wayne S wrote: >> On May 12, 2022, at 09:56, Peter Coghlan via cctalk >> wrote: >> >> Toby Thain via cctalk wrote: >>>> On 2022-05-11 7:02 p.m., Peter Coghlan via cctalk wrote: >>>> Given the normal usage that has evolved for the t

Re: DEC H7822 power supply

2022-05-12 Thread Peter Coghlan via cctalk
>> >> If I am trying to calculate the height a sea harbour wall needs to be, can I >> not consider the height of the tide and the height of the waves separately >> and add them together, just to make it easier to work it out even though I >> know that it would be physically impossible to disti

[cctalk] Re: Connecting a physical terminal via LAN to Serial Port

2022-08-01 Thread Peter Coghlan via cctalk
> > For an extra $1 now you can get integrated WiFi (and Bluetooth but > there isn't any BT software support yet) in the form of the $5 Pi > Pico W, so that's one route to talking to an IP network for IoT or > something like this. > > A neat thing about the Pico is that you can do hard real-time

[cctalk] Re: VT220 North of Boston

2022-08-08 Thread Peter Coghlan via cctalk
Boston GB, Boston USA or Boston somewhere else? Regards, Peter Coghlan (No Bostons anywhere near where I am anyway). > > Looks like both of them are North of Boston, but one is like a 19 hour drive > away and one is a half hour drive away. > > I'd guess the half hour one. :D > > -Paul > > > >>

[cctalk] Re: COMAL language in the UK?

2022-09-07 Thread Peter Coghlan via cctalk
I'm not in the UK but I think I have a COMAL paged rom image for the BBC Micro somewhere. I don't think I ever tried using it, I have no documentation for it and I don't know anything about it but if there is any interest, I will try to find it. Regards, Peter Coghlan. > > This is a query which

[cctalk] Re: TVI-921C

2022-09-14 Thread Peter Coghlan via cctalk
Mike Loewen wrote: On Wed, 14 Sep 2022, Jonathan Katz via cctalk wrote: I have a TVI-921C at the museum. I power it on and it beeps continuously. One long, solid tone that does not stop until I power it off. How do I start diagnosing this? Check the power supply voltages. After checking

[cctalk] Re: Is this a RIFA (uV3100-10 PSU)?

2022-10-23 Thread Peter Coghlan via cctalk
I'm working on cleaning up a bit of battery leakage in a MicroVAX 3100 Model 10 and while it's apart I decided to look inside the PSU (an H7822-00). It's nice and clean inside with no bulging caps. What it does have is an X2 capacitor, as shown here: https://photos.app.goo.gl/dpdqJ3tuGfsRDR3

[cctalk] Re: RDI BriteLite IPX keeps going to white screen

2022-10-29 Thread Peter Coghlan via cctalk
> > I've been trying to do a little work on the RDI BriteLite IPX I have here, but > when it runs more than a few minutes the LCD just blanks out white. The > machine > seems to still respond to commands, so it seems like it's something with the > display hardware. Even powered off and back on it

[cctalk] Re: Is this a RIFA (uV3100-10 PSU)?

2022-11-01 Thread Peter Coghlan via cctalk
On 24/10/2022 21:07, Antonio Carlini via cctalk wrote: the bitsbox one may be a teensy bit to large but the ebay one should fit nicely. Neither is too expensive even with postage so I'll buy a few, given that I do have a fair few PSUs knocking around. Turns out both sets of X2 caps I bought we

[cctalk] Re: Is this a RIFA (uV3100-10 PSU)?

2022-11-02 Thread Peter Coghlan via cctalk
Antonio Carlini via cctalk wrote: On 01/11/2022 23:10, Peter Coghlan via cctalk wrote: I've taken the boards out of a whole bunch of H7821 and H7822 PSUs to replace the electrolytics without removing the fans.  It was difficult at first but the more I did, the easier it got.  I did come a

[cctalk] Re: Seeking a Sun monitor with 13W3 interface

2022-11-08 Thread Peter Coghlan via cctalk
> > I'm seeking to buy a Sun Microsystems monitor with a 13W3 interface. > > Ideally somewhere around central Europe for pickup in person. But I'm happy > to consider shipping options as well. > I have a GDM1604B40 monitor (Sony Trinitron design) with a 13W3 connector. I don't know if it works or

[cctalk] Re: Exabyte recovery

2022-11-10 Thread Peter Coghlan via cctalk
Jon Elson via cctalk wrote: On 11/9/22 20:52, Warner Losh via cctalk wrote: I have a few old exabyte tapes of possible historic value. Who can I pay to get them recovered that has the best chance of success? Very difficult.  We were a big user of Exabyte drives for processing of physics experi

[cctalk] Re: Is this a RIFA (uV3100-10 PSU)?

2022-11-15 Thread Peter Coghlan via cctalk
On 15/11/2022 10:06, Antonio Carlini via cctalk wrote: On 24/10/2022 21:07, Antonio Carlini via cctalk wrote: the bitsbox one may be a teensy bit to large but the ebay one should fit nicely. Neither is too expensive even with postage so I'll buy a few, given that I do have a fair few PSUs knock

[cctalk] Re: Is this a RIFA (uV3100-10 PSU)?

2022-11-18 Thread Peter Coghlan via cctalk
Maciej W. Rozycki via cctalk wrote: > > Same here, five 1800uF 25V caps to replace in the H7821 according to my > notes. Overall if you spot a cap that says SXF on it, then replace it > right away whether already leaking or not. These were made by Chemi-con. > Other Chemi-con lines reported

[cctalk] Re: Identifying a Failed Diode in a Rainbow H7842 Power Supply

2022-11-20 Thread Peter Coghlan via cctalk
Hi Rob, I'm only guessing here. I think the sequence may have been that the main switching transistor failed first as it would be under more stress than a diode in the base circuit. If the transistor shorted E-B-C then the HT would become connected to the circuitry at it's base which would be co

[cctalk] Re: Identifying a Failed Diode in a Rainbow H7842 Power Supply

2022-11-20 Thread Peter Coghlan via cctalk
outputs with working rectifiers when power is applied through the light bulb and a lesser or no voltage rise on an output which has a shorted rectifier or other issue that needs closer inspection. It also means there is no need to hide behind the sofa when you switch it on :-) Regards, Peter. &g

[cctalk] Re: Identifying a Failed Diode in a Rainbow H7842 Power Supply

2022-11-23 Thread Peter Coghlan via cctalk
Don, Does the url suggest you may have searched for a H5901 rather than a H9501? Regards, Peter Coghlan. > > NTE seems to turn up these possibilities for a H9501. > > https://www.nteinc.com/search/search/search.php?ss360Query=H5901 > > Don Resor > > Sent from someone's iPhone > >> On Nov 23,

[cctalk] Re: Identifying a Failed Diode in a Rainbow H7842 Power Supply

2022-11-25 Thread Peter Coghlan via cctalk
It is often possible to infer the component ratings needed from the other components around them. A component in the base circuit of a transistor is likely to experience lower currents and voltages than one in the collector circuit. In this case, we can see from Tony's diagram that there is a 2.7

[cctalk] Re: Identifying a Failed Diode in a Rainbow H7842 Power Supply

2022-11-27 Thread Peter Coghlan via cctalk
> > I think that a good thing is to ramp up the input voltage slowly. Use a > bench PSU to supply the Vstart voltage and then use a variac with > insulation transformer to feed the rest if the supply. Use some small > loads on the 5V and 12V outputs. Now you can safely probe the PSU and > monitor

[cctalk] Re: Guidance on repairing Dec PDP 11 System

2022-11-27 Thread Peter Coghlan via cctalk
I am looking for advice to get the 11/34 system up and running. I have started to put together a site to document my progress, to stay on track with the repair effort. The system has 2 rl02 drives, and an attached 9 track tape drive. I had worked to repair a power supply issue at first, there

[cctalk] Re: unpleasant odor from VT100

2022-12-20 Thread Peter Coghlan via cctalk
I had something similar with a VT220. I didn't get around to investigating it before the flyback transformer failed :-( I can only suggest to run it for a short time with the cover off and the lights out while looking for any glows / discharges around the flyback transformer, the EHT cable, the E

[cctalk] Re: unpleasant odor from VT100

2022-12-20 Thread Peter Coghlan via cctalk
istribution board while the unit was > powered on, it does not seem to be overheating. > > On Tue, Dec 20, 2022 at 1:09 PM Peter Coghlan via cctalk < > cctalk@classiccmp.org> wrote: > >> I had something similar with a VT220. I didn't get around to >> invest

[cctalk] Re: what is on topic?

2022-12-21 Thread Peter Coghlan via cctalk
> > Windows 2003 and XP is about as obsolete now as the IBM PC was in 1995. > Probably more so. XP is popular on Vogons but I'm sure considerably less > then 5% of computers actually host it. > > There's also the issue of beating a dead horse. There will always and > forever (and forever...) be som

[cctalk] Re: AI applied to vintage interests

2023-01-17 Thread Peter Coghlan via cctalk
Fred Cisin wrote: How well does it do on something "simple", and less esoteric, such as translating FORTRAN to BASIC? On Mon, 16 Jan 2023, Chuck Guzis via cctalk wrote: How about FORTRAN to RPG? Certainly more of a challenge! But, a good way to quanitfy how far along they are getting on it.

[cctalk] Re: AI applied to vintage interests

2023-01-17 Thread Peter Coghlan via cctalk
Peter Corlett wrote: > On Tue, Jan 17, 2023 at 10:16:18AM +0000, Peter Coghlan via cctalk wrote: > [...] >> How about translating code from Z80 which has several registers to 6502 >> with rather fewer? That would seem to need some more intelligent thinking >> on how to

[cctalk] Re: AI applied to vintage interests

2023-01-18 Thread Peter Coghlan via cctalk
Chuck Guzis via cctalk wrote: > On 1/17/23 19:14, Chris via cctalk wrote: >> My worst nightmare is some fiendish AI turning me into a really beautiful >> woman. Maybe with no arms. The Terminator future doesn't seem so bad by >> comparison. >> > My worst nightmare, which is sure to become reality i

[cctalk] Re: AI applied to vintage interests

2023-01-18 Thread Peter Coghlan via cctalk
I telephoned the customer service department at a railway company. I think the person I spoke to knew less about trains than this thing knows about a PDP-11. Maybe they are using AI to do telephone answering now? Regards, Peter Coghlan. Jay Logue via cctalk wrote: I don't know about guessing

[cctalk] Re: scsi

2023-01-21 Thread Peter Coghlan via cctalk
Paul Berger via cctalk wrote: Indeed not not all SCSI terminators are created equal, there where three types of signalling used Single Ended (SE) High Voltage Differential (HVD)  and Low Voltage Differential (LVD). LVD was created to squeeze a bit more speed out of parallel SCSI. That's n

[cctalk] Re: cctalk archives not updating

2023-01-28 Thread Peter Coghlan via cctalk
It appears there was some sort of coup in July 2022. The mailing list owner was apparantly replaced and the list was moved from where it was previously hosted to somewhere new. There were some vague declarations about needing to deal with archives but I never saw any formal or informal announcemen

[cctalk] Re: cctalk archives not updating

2023-01-28 Thread Peter Coghlan via cctalk
27;m still in the dark. You seem to know something about it? Can you enlighten those of us that don't? Regards, Peter Coghlan. Patrick Finnegan wrote: > > If by "coup" you mean rescued from getting turned off, then yes. > > Patrick Finnegan > > On Sat, Jan 28, 20

[cctalk] Re: Low cost logic analyzer

2023-03-14 Thread Peter Coghlan via cctalk
> > There are some nice mixed signal oscilloscopes made by Rigol (Chinese) at a > very affordable price. > Until just over a year ago, buying very afforadable Russian oil and gas also seemed like a great idea with no downsides compared to getting these products elsewhere. Regards, Peter Coghlan.

[cctalk] AT&T Customer Service

2023-04-18 Thread Peter Coghlan via cctalk
Fred Cisin wrote: On Mon, 17 Apr 2023, AT&T Customer Service via cctalk wrote: Sorry, I forgot to post the location.  I'm in Kent, Washington. USA.  disregard the AT&T customer service.  Have E-mails in to them. not sure what going on there, but its at&tso anything is possible. With a user na

[cctalk] Re: Rainbow H7842 PSU Fault

2023-04-22 Thread Peter Coghlan via cctalk
> > This seems to be because I measure a steady 0.6V on pin 6 of the transformer > (p4, PSU Sheet 3). I just can't imagine where it might be coming from as the > chopper won't be running. I had previously removed the transformer and there > are no shorts between the pin 5-pin 6 winding and any of t

[cctalk] Re: Rainbow H7842 PSU Fault

2023-04-22 Thread Peter Coghlan via cctalk
> > This seems to be because I measure a steady 0.6V on pin 6 of the transformer > (p4, PSU Sheet 3). I just can't imagine where it might be coming from as the > chopper won't be running. I had previously removed the transformer and there > are no shorts between the pin 5-pin 6 winding and any of

[cctalk] Re: Rainbow H7842 PSU Fault

2023-04-23 Thread Peter Coghlan via cctalk
Hi Rob, > > Thanks for the various replies. Here are my responses and further > observations. > > I was asked if I had a load on the PSU while bench testing it. The answer to > that is no. > I initially thought that the +0.6V on the -12V line might have been arriving there via a load which was c

[cctalk] Re: Rainbow H7842 PSU Fault

2023-04-29 Thread Peter Coghlan via cctalk
> > Yes, that is certainly the problem. Presumably more current is flowing > through the current sense resistor than should be. > Do you mean when the power supply is connected to the mains here? If we are still talking about the test case when you are applying an external supply to Vstart only,

[cctalk] Re: Rainbow H7842 PSU Fault

2023-05-01 Thread Peter Coghlan via cctalk
It seems a bit odd that a power supply from someone like DEC of that era would be designed to depend so critically on the absolute value of a rail used for startup purposes. The output of the replacement 7812 varying between 12.2V and 12.4V suggest that the 7812 itself could be faulty. Or maybe

[cctalk] Re: Rainbow H7842 PSU Fault

2023-05-07 Thread Peter Coghlan via cctalk
> > The comments about the tolerance of the 7812 were right, it doesn’t > appear to be an issue with the replacement 7812 regulator because when > I tried using the bench PSU to feed exactly 12V to the circuit from the > output of the 7812 the comparator still gave the wrong result. It was > still

[cctalk] Re: Rainbow H7842 PSU Fault

2023-05-08 Thread Peter Coghlan via cctalk
> > > > -Original Message- > > From: Peter Coghlan via cctalk > > Sent: 07 May 2023 10:34 > > To: General Discussion: On-Topic and Off-Topic Posts > > > > Cc: Peter Coghlan > > Subject: [cctalk] Re: Rainbow H7842 PSU Fault > > &g

[cctalk] Re: Rainbow H7842 PSU Fault

2023-05-09 Thread Peter Coghlan via cctalk
> > I am going to read your answer more carefully later. But I wanted to check > one thing. I measured the base-emitter voltage as negative in both cases, > and yet the TIP121 appears to be conducting on the bad PSU. Surely that > means that the TIP121 is not working correctly? > I'd be very reluc

[cctalk] Re: Rainbow H7842 PSU Fault

2023-05-10 Thread Peter Coghlan via cctalk
> > I will do all the suggested checks, but I won't be able to do this for a > number of days. However, I wanted to understand something in the meantime. > The conditions I am applying are (I think!) what would happen during > startup, and during startup the control board has to make the PWM run,

[cctalk] Re: Rainbow H7842 PSU Fault

2023-05-20 Thread Peter Coghlan via cctalk
> > > > -Original Message- > > From: Peter Coghlan via cctalk > > Sent: 10 May 2023 12:04 > > To: 'General Discussion: On-Topic and Off-Topic Posts' > > > > Cc: Peter Coghlan > > Subject: [cctalk] Re: Rainbow H7842 PSU Faul

[cctalk] Re: Rainbow H7842 PSU Fault

2023-05-25 Thread Peter Coghlan via cctalk
> > This evening I went to check Vstart for any oscillation. However, all of a > sudden, the current draw is down to 85mA and PWM has started working. I am > at a loss to explain it. I wondered if there might be a dry joint, but I > have tried a few light taps and shakes and it continues to work. P

Re: Scrounging - was Floating point routines for the 6809

2017-03-30 Thread Peter Coghlan via cctalk
> > Or the time an English co-worker related the story surrounding her > initial job interval in the US. She described the stunned look on the > face of the desk clerk at the local Holiday Inn when she asked to be > knocked up at 7:30 the next morning. > This reminds me of the rather surprised lo

Re: Reviving VT220?

2017-04-28 Thread Peter Coghlan via cctalk
> Hi all, > > A colleague and I are trying to get a VT220 working again as it recently > died on us. We are hoping to set up a few items for the mid-80s > (including this terminal) to show the graduands what it would have been > like if they were doing their CompSci degree 30 years ago. > > It look

Re: Reviving VT220?

2017-04-28 Thread Peter Coghlan via cctalk
> > Thanks for the information, Peter. It makes me want to try and test a > few of the components around the flyback. > It would also be good to check the stuff like voltages on the base of the CRT and that the CRT heater is glowing. You could have a problem that is nothing to do with the flyback

Re: xv and VMS

2017-05-16 Thread Peter Coghlan via cctalk
> > Is anyone out there using X11 on VMS and the xv image viewer? > Yes. Why do you ask? > -- > David Griffith > d...@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

Re: xv and VMS

2017-05-17 Thread Peter Coghlan via cctalk
> > I ask because I've been scraping together patches for xv and collecting > them into a Github repo[1]. I've finished adding all the patches > collected by Greg Roelofs, patches from OpenBSD, and now I'm working on > eliminating unsafe calls like strcpy() and sprintf(). Could I get some of

Re: DEC terminals and classic server computing

2017-05-29 Thread Peter Coghlan via cctalk
> > The DEC PS/2 keyboards that you could use with the VT510, VT520, VT525 > include the LK450, LK460, and LK461. > My VT510 has an LK411. I don't know if this is what it came with originally but I suspect it is. It works fine with it anyway. Regards, Peter Coghlan.

RE: Line printer art: (was Re: tape baking)

2017-07-07 Thread Peter Coghlan via cctalk
> > > > > If anyone's running Hercules or some other uses-EBCDIC emulator, here's > > the link to the .tap image file. > > > > https://app.box.com/s/8rxbihjjnw5zdkesym4cjwqswekufagh > > > > --Chuck > > Sadly I don't think that's much use on Hercules as it needs an AWS or HET > file. Is there a fo

Re: Ibm rs6000 7025-f50

2017-07-27 Thread Peter Coghlan via cctalk
> > I have a CD still in the original shrink wrap of 5765-393 AIX 4.1.4 > for Clients, LCD4-0114-00. Can't be that hard to find. I have no use > for it myself anymore, got rid of my RS/6000 systems a few years back. > I have a CD which has "5765-393 AIX 4.1.4 for Server for D5 Processors" and "LCD

RE: DECstation 220. Another Impasse

2017-08-15 Thread Peter Coghlan via cctalk
> > I have looked at this problem a little more. I have two motherboards, > neither of which work, but one at least produces a corrupted video pattern. > The one that works best appears not to be writing to the video memory. When > I look at the EMEM pin on the Paradise PVGA1A chip I can see a sign

Re: Plotter + Tape drive

2017-08-16 Thread Peter Coghlan via cctalk
> > It is SCSI. > Hi Andy, In that case, I am interested too. I am on the East coast of Ireland. I don't suppose you make regular trips to North Wales or anything like that :-) Regards, Peter Coghlan.

Re: HP Draftmaster I, Power Supply repair

2017-08-30 Thread Peter Coghlan via cctalk
> > I think that I'm responsible for the dead, as the plotter stood in an attic > for 20 years, meanwhile power was raised from 220 to 230v (+-10%) in Europe. > The distribution voltage had previously been specified as 220V in some European countries and 240V in others but the specification was t

RE: BitNET (Was: RE: RIP Jerry Pournelle - Firsts)

2017-09-16 Thread Peter Coghlan via cctalk
Hi Bill and Dave, I have fond memories of BITNET in a university environment in the early 1990s on VM/CMS and on VAX/VMS. Some years ago, I went searching on the web for information about it and found almost nothing. It was as if it had been erased from history. I did find a single website whic

Re: H7878 Fails Under Even Moderate Load

2017-09-17 Thread Peter Coghlan via cctalk
> > Can anyone explain the behaviour? > It's hard to know what to do from a distance but here's what I think I'd look at if I was faced with this problem. I think failing under moderate load could be explained by one or more of the following possibilities and probably others I haven't thought of:

Re: DECstation 5000/240 Thickwire Connector

2017-10-04 Thread Peter Coghlan via cctalk
> > The thickwire connector on my DECstation 5000/240 does not have the sliding > lock on it, instead it has standoffs with threaded screw holes (like any > normal serial/parallel connector). This means that the thickwire adapters I > have won't connect properly because their locking studs are bloc

RE: The origin of the phrases ATA and IDE [WAS:RE: formatting MFM drives on a IBM PC]

2017-10-05 Thread Peter Coghlan via cctalk
> > That concurs with my observation that SCSI was initially an Apple > > convention. > > I can recall conversations about SASI vs. Apple SCSI. > > And like Fred, I don't believe that it does any such thing. > >Rich Me too. Given ho

Re: The origin of SCSI [WAS:RE: The origin of the phrases ATA and IDE ]

2017-10-05 Thread Peter Coghlan via cctalk
The biggest problem you had was the requirement to assert ATN when selected properly.  Later the tag queuing caused huge headaches as manufacturers implemented that feature. It eventually was made mandatory for the most part by linux, and perhaps Windows requiring the tag queuing drilled

Re: Aaron Nabil & pdp-8.org

2017-10-06 Thread Peter Coghlan via cctalk
Jim Stephens wrote: On 10/5/2017 11:28 PM, Vincent Slyngstad via cctalk wrote: From: "Zane Healy via cctalk" Sent: Thursday, October 05, 2017 9:09 PM I'm not sure if Aaron's website was offline prior to the last couple days or not, as I honestly don't remember the last time that I visited, b

Re: DEC Alpha 3000 and OpenVMS 8.4

2017-10-13 Thread Peter Coghlan via cctalk
Douglas Taylor wrote: I'm trying to bring up an Alpha machine, a 3000-300, the hardware is working fine, but I have some questions- The system disk is an RZ26 (1.06GB) and I installed the OS and one layered product and the disk is full.  How much disk space is needed for 8.4? I have sev

Re: tandem computers cartridge tapes

2017-10-15 Thread Peter Coghlan via cctalk
Camiel Vanderhoeven wrote: > >On 10/14/17, 7:55 PM, "cctalk on behalf of steve shumaker via cctalk" > wrote: > > >>On 10/14/2017 10:42 AM, Camiel Vanderhoeven wrote: >>> On 10/14/17, 7:22 PM, "cctalk on behalf of steve shumaker via cctalk" >>> >>>wrote: >>> >>> found as part of the stack save

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