Re: ADM 3a with no horizontal scan

> On Apr 8, 2016, at 11:59, Seth Morabito wrote: > One more observation: Two of the three +5V regulators cut out > when their input voltage exceeds about 11.5V. The input voltage > comes from a 9.4VAC winding on the primary transformer. Input ripple > is VERY low, maybe 200mV.

RE: really old test equip

On Fri, 8 Apr 2016, Cindy Croxton wrote: No sorry, I do not recall the manufacturer. Most of the boxes had grey pattern bases with black lids, but a few were brown pattern boxes with dark brown lids. Not very helpful, I know. I should have taken some pics! Cindy Hi Cindy, Actually somewhat

Re: Voltage regulator with alternate voltage source...

On 2016-Apr-08, at 11:58 AM, Bill Sudbrink wrote: > I don't know why I bothering to be coy about it... > > My unit here: > > http://wsudbrink.dyndns.org:8080/images/cyclops-latest/P4060005.JPG > http://wsudbrink.dyndns.org:8080/images/cyclops-latest/P4060006.JPG > > Actually, I'm further

Re: Shipping big things across the atlantic.

Thanks everyone who replied. The seller stopped communicating with me so this time it's a no-go. But I'm sure there will be a next time :) /P On 04/01/2016 11:48 AM, Pontus Pihlgren wrote: Hi. I'm considering to ship an empty full height rack from the USA to Sweden. It is definitely

Re: Voltage regulator with alternate voltage source...

On 2016-Apr-08, at 11:27 AM, Mouse wrote: >> I archive all data sheets I run across and I found this information >> on both TI and Fairchild data sheets for the 78H05, LM340 and LM78XX >> devices - it is usually under a heading called Application Hints and >> for some reason Fairchild have

RE: really old test equip

-Original Message- From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Sean Caron Sent: Friday, April 08, 2016 4:42 PM To: General Discussion: On-Topic and Off-Topic Posts Subject: Re: really old test equip On Fri, 8 Apr 2016, Cindy Croxton wrote: > When I was at the

Re: really old test equip

On Fri, 8 Apr 2016, Cindy Croxton wrote: When I was at the recycler last week, I saw a lot of really OLD test equipment. I started looking through it to see if there were things I could recognize, but the closest thing I could figure out was a 1940s telephone equipment tester. All of these were

really old test equip

When I was at the recycler last week, I saw a lot of really OLD test equipment. I started looking through it to see if there were things I could recognize, but the closest thing I could figure out was a 1940s telephone equipment tester. All of these were portable, with lids that closed with

A tale of a chip and a socket

So I just had the incredibly amusing experience of managing to repair an -11/04 CPU by un-soldering a chip, putting in a socket, and putting _the same chip_ back in that socket! Before you go 'WTF?!?!', let me explain what happened. The CPU wouldn't run, and in poking around, I stumbled on the

RE: Voltage regulator with alternate voltage source...

> > > 1) I have a 12 volt DC supply. 12 volts seems to be > > >within the VIN range for the 7805s whose data > > >sheets I've now read. Can I simply apply 12 volts? > > > > Yes, but that regulator might get mighty hot! I would > > not do this for fear of cooking the poor thing. > >

Re: Why do good floppy disks go bad?

On 04/08/2016 12:11 PM, Tom Gardner wrote: > Sorry, to a EE they are all epoxies, but: Gorilla glue is an epoxy? News to me. Polyurethane is far from stable over the long term and exhibits hygroscopic properties: For example, vide:

RE: Voltage regulator with alternate voltage source...

> > First, a few quick "whys": > > 1) The 7805 is actually a Motorola MC7805CP, date >code 7308 with gold leads. Very hard to exactly >replace. Any reason why it would have to be an exact replacement? In any case, the behaviour of the 7805 if you apply a voltage to the output with

Re: Why do good floppy disks go bad?

> On Apr 8, 2016, at 3:11 PM, Tom Gardner wrote: > > Sorry, to a EE they are all epoxies, but: > > "BINDER: A polymer such as polyester-polyurethane used to bind magnetic > particles together and adhere them to the base film in the manufacturing of > magnetic media." >

Re: Why do good floppy disks go bad?

>> Entropy: Could the rust on the cookie be de-oxidizing, and turning back int$ > No. If that were true, iron ore would spontaneously turn into iron. Unfort$ Anyone keep their floppies in a hydrogen (or, more generally, reducing) atmosphere? (Cue xkcd #1426. :-) /~\ The ASCII

RE: Why do good floppy disks go bad?

Sorry, to a EE they are all epoxies, but: "BINDER: A polymer such as polyester-polyurethane used to bind magnetic particles together and adhere them to the base film in the manufacturing of magnetic media." http://www.fujifilmusa.com/shared/bin/Magnetic_Media_Terminology.pdf "Polyester

Re: ADM 3a with no horizontal scan

* On Fri, Apr 08, 2016 at 02:33:25PM -0400, Mouse wrote: > > Today, for whatever reason, my Variac was turned down to 110V, and I > > didn't notice. I turned on the ADM 3a, and... it's fine. [...] > > Fascinating! > > I have trouble imagining what sort of fault

RE: Voltage regulator with alternate voltage source...

I don't know why I bothering to be coy about it... My unit here: http://wsudbrink.dyndns.org:8080/images/cyclops-latest/P4060005.JPG http://wsudbrink.dyndns.org:8080/images/cyclops-latest/P4060006.JPG Actually, I'm further along than that, but I don't have more recent photos. Original unit

RE: Voltage regulator with alternate voltage source...

William Donzelli wrote: > > 1) The 7805 is actually a Motorola MC7805CP, date > >code 7308 with gold leads. Very hard to exactly > >replace. > > Is that the big flat plastic package with the wide > flat leads? Nope, purple ceramic. The heat transfer plate is gold plated too. > > 1) I

Re: Voltage regulator with alternate voltage source...

Silly question, but then I'm feeling silly today: Why not just connect the output and input of the 7805 together and power from the normal +8 line with your +5 supply? --Chuck

Re: Voltage regulator with alternate voltage source...

> 1) The 7805 is actually a Motorola MC7805CP, date >code 7308 with gold leads. Very hard to exactly >replace. Is that the big flat plastic package with the wide flat leads? I might have a few of those around, but I agree, not an easy variant to find. > 1) I have a 12 volt DC supply.

Re: ADM 3a with no horizontal scan

> Today, for whatever reason, my Variac was turned down to 110V, and I > didn't notice. I turned on the ADM 3a, and... it's fine. [...] Fascinating! I have trouble imagining what sort of fault could cause those symptoms. I would have agreed with whoever (tony, I think) said that if you have HV

Re: Voltage regulator with alternate voltage source...

> I archive all data sheets I run across and I found this information > on both TI and Fairchild data sheets for the 78H05, LM340 and LM78XX > devices - it is usually under a heading called Application Hints and > for some reason Fairchild have removed these Hints from the sheets > you quote. >

RE: Voltage regulator with alternate voltage source...

First, a few quick "whys": 1) The 7805 is actually a Motorola MC7805CP, date code 7308 with gold leads. Very hard to exactly replace. 2) As per the design of the unit, the 7805 is soldered to the foil side of a single sided, copper clad circuit board with no through hole plating.

Re: Voltage regulator with alternate voltage source...

Keep in mind that "not powered" and "open" are very different things. What do the data sheets say? I will admit that this is all careening towards the academic at this point... -- Will On Fri, Apr 8, 2016 at 1:31 PM, John Robertson wrote: > On 04/08/2016 8:54 AM, wulfman

Re: Voltage regulator with alternate voltage source...

On 04/08/2016 8:54 AM, wulfman wrote: https://www.fairchildsemi.com/datasheets/LM/LM7805.pdf http://www.ti.com/lit/ds/symlink/lm78l05.pdf ( page 8 gives you the internals for a low power version ) Nothing in the data sheet saying you cant apply voltage to the output. As per the low power

Re: ADM 3a with no horizontal scan

OK, I made a very interesting discovery today. When I'm working on a project on my workbench, I normally have it plugged into a Variac. This ADM 3a is no exception. I bring up voltage slowly on any unknown old electronics, and then let it sit at our normal wall voltage - which currently reads

RE: Dumb terminals for daily use today; failure scenarios

> If one were to use a dumb CRT terminal from the early '70s regularly in > this day and age, would it be more prone to hardware failure than if it > were kept in storage or just kept to look at but powered off? If you never turn it on, how will you know if the hardware has failed? More

Dumb terminals for daily use today; failure scenarios

If one were to use a dumb CRT terminal from the early '70s regularly in this day and age, would it be more prone to hardware failure than if it were kept in storage or just kept to look at but powered off? -- Eric Christopherson

Re: Voltage regulator with alternate voltage source...

https://www.fairchildsemi.com/datasheets/LM/LM7805.pdf http://www.ti.com/lit/ds/symlink/lm78l05.pdf ( page 8 gives you the internals for a low power version ) Nothing in the data sheet saying you cant apply voltage to the output. As per the low power version circuit diagram i cant see how you

Re: VCF Europe, April 30th - May 1st, Munich + registration for VCF Berlin

That's pretty nearly what it says. I'd tweak it as follows. paul > On Apr 8, 2016, at 8:42 AM, R SMALLWOOD wrote: > > >> > historische Computer und Rechentechnik> > The Vintage Computing - Berlin (VCFB) is an event for collectors of old > computers and

RE: ADM 3a with no horizontal scan

> > This particular 3a has no horizontal scan. None at all. I just get a > vertical line down the center of the screen. First thing I checked was > the horizontal deflector on the yoke, which seems secure. I am going to assume this is a conventional design, I would be very surprised if not. In

Re: Space Travel (was Re: Data General Nova Star Trek)

On Fri, Apr 08, 2016 at 05:33:43AM -0700, Charles Anthony wrote: > > http://www.chdickman.com/pdp8/spacewar/ built his own VC8/I for his PDP-8 > and runs the PDP-8 version of space war on it. He lists the IOT > instructions for the VC8/I; they are similar to the 338. Ohh, that looks very doable,

Re: Pinging Joe Rigdon

Yo, When I lived in Florida, I would see Joe several times a year. Since I moved 10 years ago, we have lost contact. His wife Sherry, daughter Amy, and Son Adam, do have facebook profiles. Just do a search for "Rigdon Oviedo" (Florida) and you can find some links to those family members but

Re: VCF Europe, April 30th - May 1st, Munich + registration for VCF Berlin

The Vintage Computing - Berlin (VCFB) is an event for collectors of old computers and calculators. From : stuebera...@yahoo.de Date : 06/04/2016 - 23:56 (GMTDT) To : cctalk@classiccmp.org Subject : VCF Europe, April 30th - May 1st, Munich + registration for VCF Berlin Hi list, the 17th

Re: Space Travel (was Re: Data General Nova Star Trek)

On Thu, Apr 7, 2016 at 9:35 PM, Pontus Pihlgren wrote: > On Thu, Apr 07, 2016 at 04:08:42PM -0700, Charles Anthony wrote: > > > > I have some code that does an X-11 emulation of the Atari Tempest vector > > graphics display; I'm thinking of wedging it into the simh PDP8 code

Re: ADM 3a with no horizontal scan

> > I've been on a tear trying to resurrect old projects here, and next on > the list is an ADM 3a. > > This particular 3a has no horizontal scan. None at all. I just get a > vertical line down the center of the screen. First thing I checked was > the horizontal deflector on the yoke, which seems

Re: Voltage regulator with alternate voltage source...

On 04/07/2016 4:41 PM, William Donzelli wrote: Does this warning assume that there is something on Vin, and not open? With a quick look at the internal schematic of an old-school 7805, it seems like what Bill suggests (leaving Vin open) will not actually do much. -- Will This warning is for