A less painful way may be to lift the output pin of the regulator from its via. Or (and this is evil, but works, and is can be better than losing all your unsocketted chips), cut the trace after output of the regulator. You can always use a piece of foil tape or wire to effect a repair. This may detract from the ultimate value of the board, but you're far less likely to wreck it than removing irreplacable socketted chips. --John

-----Original Message----- From: cctalk-admin(a)classiccmp.org [mailto:cctalk-admin@classiccmp.org]On Behalf Of Tony Duell Sent: Tuesday, September 24, 2002 20:24 To: cctalk(a)classiccmp.org Subject: Re: Altair-what do I do first _Neve_ plug in a classic computer without checking it first! [Good advice on electrolytic caps deleted] first. not The amin problem with S100 systems is that the PSU lines on the bus are unregulated. The voltage regulators are on each card. And this means that a defective regulator _on a card_ will wipe out all the chips on that card, and may even put high voltages onto the bus lines and damage other cards. Therefore, do as suggested and get the unregulated PSU working first. Then take the cards (one at a time) and remove all socketed ICs. Make a diagram first, of course if you don't have the schematics/layout diagrams for that card. You'd better hope that the expensive/rare ICs (CPU, ROMs, RAM, LSI I/O chips) are socketed. Then put the (essentially bare) card in the backplane and check the outputs of the regulators on that card. Repeat for all the cards you have. Put the ICs back into a card before starting on the next one (unless you are a lot better organised than me!) Then, and only then do you put populated cards into the backplane and start testing logic functions. -tony

I will consider serious offers of trade.. things I would like in working order please.

Other HP gear - HP71, HP74

At 08:37 PM 9/26/02 -0700, you wrote: Or a TI-74? Or perhaps even a HP-94?

Joe

Ron Hudson <rhudson(a)cnonline.net> writes: [...] Oooh, I want an HP-74 also!!! Despite having no clue what it is :-) Did you perhaps mean HP-75C or HP-75D?

A word of warning if you try this. Some (only a few, but) 3-terminal regulators are unstable if don't properly decouple them. So if you totally disconnect the output pin, add a 100nF capacitor between the disconnected pin and the ground rail. It may be impossible to do this, BTW, if the regulator is a TO3 (metal can) one _and_ the power distribution is on an internal power plane of a multi-layer PCB. Multi-layer PCBs are not common in S100 machines, but they did exist at that time. Indeed. Don't just bridge the trace with a blob of solder, though. It will give problems later.... In fact _always_ solder a wire across a track break or cut rather than just using a blob of solder. I've never damaged a chip removing it from a socket. But desoldering irreplacable chips (i.e. removing unsocketed ones) is something I'd not want to do too often. It depends on the board. If you can pull almost all the ICs, perhaps just leving a bit of TTL, then try it like that. TTL is still fairly easy to get. If, on the other hand you've got soldered-in RAMs, or LSI parts, or... then disconnect the regulator from the rest of the board rather then trying to remove the ICs. -tony

Peter, yeah, this seems like an easy approach. Question: could a simple 6.2V Zener be installed reverse-biased from the 5V regulator output to ground? Seems like you'd want inline fuses between the unregulated supply and the backplace as well for this kind of test... Patrick

A better solution is to use a crowbar circuit. It's only 3 components! +5V o--------------+-----------------------+ | | | | --- | ^ | 5v6 Zener | | | +-------------------\ | | \ V Thryistor/SCR / ------ to carry full PSU current \ 100R | / | \ | | | | | 0V o---------------+-----------------------+ You want something that will fail safely if the crowbar trips, sure.... A fuse is a pretty good choice. -tony

Hopefully on the up side.... when things get better, prices should have fallen significantly and beginning grabs at bargains should be good for all... the times of fat wallets and insultingly high Ebay prices are now over and lean times and good bargains should be on their way.

Ernest wrote: You said it. The economy is not only far worse than people generally admit, but if you pay close attention to recent news, all signs point to another sharp decline that's already underway. You want a recovery? We had it, baby! That anemic little blip was it. It's all downhill from here. Despite assurances that "the economy is basically sound",

----- Original Message ----- From: "Joe" <rigdonj(a)cfl.rr.comRepublican pals, that's who! I seem to recall that most of the bastards donated pretty much equal amounts of money to both sides of the aisle.

get back to old, cranky, computers.

I did manage to pick up a dual trace Tektronix RM-503 scope on ebay for $49.99 today :-D

Ernest wrote: You said it. The economy is not only far worse than people generally admit, but if you pay close attention to recent news, all signs point to another sharp decline that's already underway. You want a recovery? We had it, baby! That anemic little blip was it. It's all downhill from here. Despite assurances that "the economy is basically sound", too many bad factors are coming together at the same time. Many are preventable; some are inevitable. Investor confidence is low, consumers are holding onto their cash, unemployment continues to rise, and foreign investors are pulling out of the US market in droves, perceiving rightly or wrongly that the US leadership is neglecting fiscal policy (or worse, actively screwing things up), and creating problems for global stability due to reckless and/or unilateral foreign policy. Oil prices are headed upward, mostly due to defective foreign policy, which is always harmful to the economy, and the odds are good that a lot of European investors will yank their holdings out of US markets and put them into Europe or Asia. There's no up-side. There's no turn-around, or even economic news that hints at one.

Of course, this kind of condition just exacerbates the tendency of people to hold tighter onto their income and cut spending, in a downward spiral. In the absence of inspiring leadership to reverse the trend, it's going to be a while before people are going to spend, let along re-enter the stock markets in large numbers needed to bring things back. Bleh. That's my analysis, take it or leave it. :) On the bright side, now that more and more people are aware of the value of these old systems, maybe a lot more will be spared from the dumpster and will end up on e-bay. That ought to increase the supply at least. Supply-side economics says that means the price should drop. :) -- Ross

I agree...I've definitely cut back on collecting this year (not getting a paycheck made that decision easy)...it's so hard to window shop! But what amazes me is that some systems have not come down in price and in some cases set records (e.g. Apple Lisa 1, Altairs, SOL-20s, Apple I etc.)...I am amazed that some people can drop that much cash in this economy.

I also observed that the supply has not gone up...I would expect more systems on the market as people would sell their "luxuries" to raise cash. I just haven't seen it. Any one agree?

--- Chandra Bajpai <cbajpai(a)attbi.com> wrote: I am amazed that some people can drop that I don't. The recession is not that serious for this to happen, median household income declined 2.2% last year, and unemployment went up 1%, that tells me the overwhelming majority of collectors still have their jobs and adequate income to collect.

steve __________________________________________________ Do you Yahoo!? New DSL Internet Access from SBC & Yahoo! http://sbc.yahoo.com

These numbers don't sound too serious, until you realize the nature of this unemployment (many highly-skilled, college-educated workers) vs. the employment (retail, minimum-wage, or low-wage jobs.) I know several qualified engineers working far below their ability. They're being counted as employed, but at a far lower salary, doing something they're overqualified for. Also, unemployment is grossly under-reported. There are lots of people who are out of work long enough now, that they're not being counted as unemployed anymore, due to some trickery enacted back in the 80s to make recessions seem less severe.

At 09:54 PM 9/27/02 -0700, Wayne M. Smith wrote: > >Whatever the condition of the economy, it isn't depressing the prices of

>stuff on eBay. I haven't bought much at all on eBay this year -- and it's

Do you mean that you can't automaticly steal an auction win just by

Joe :-)

On Fri, 27 Sep 2002, Chandra Bajpai wrote: Those were the truly smart people who realized it was a bubble and pulled out at the peak ;)

I think the psychology is that people are not willing to let their precious gems go for less than they think they're worth, certainly not for less than they paid for them.

Everyone seems to be waiting for the immaculate economic recovery that Bush keeps promising. I hope everyone is planning to vote in this year's elections.

On Fri, 27 Sep 2002, Joe wrote:

It goes without saying that we will not.

I don't know. Maybe we could get Perot to run again. Hell, even Jesse Ventura would be an improvement over the candidates that we've had in the last few elections.

ANYBODY who would deliberately run for office, by that action has demonstrated that they are unfit for it.

ANYBODY who would deliberately run for office, by that action has demonstrated that they are unfit for it.

On Sat, 28 Sep 2002, Doc Shipley wrote: I gave some of my programming students an assignment of completing the program in "Nine Billion Names of God".

Now that was punch card output right! :)

True but having the entire print out done with modern equipment don't feel right with the era of the story. BTW how big would that printout be?

On Fri, 27 Sep 2002, Joe wrote: I voted for Nader. I'd do it again. I also voted for Ross Perot in '92 (?), and I'd have voted for him more if he'd run again. Nader is a fanatic, and Perot is a crook, but at least neither one is owned.

At 03:44 PM 9/27/02 -0700, you wrote: Given the choice between "I invented the internet" Gore and "Let's

Joe

Guys, I lived under communism. I am very happy here. You are all welcome to move. Regards - Mike

Sellam - I agree, completely. I also voted for Perot. But, between Clinton and Bush, at least to me, there is a world of difference. I still cannot believe that the majority of the American people voted for Clinton, for two terms. I am not claiming that Bush is perfect, but, he is a heck of a lot better in every respect than Clinton, from what I can see, from an engineer's perspective. As someone else pointed out previously, the people that can really do a decent job at being president, unfortunately will not run, or do not have the finances to even get it started if they were to. So, our choices are limited. But, at least, we do have choices. Fortunately in this country, I believe we have the momentum, and the will of the American people, to make things continue, properly, during any administration. Fluctuations in economy and world opinion will continue regardless. I am a consultant, for the military, and as of the new fiscal year I do not have a job. I do not blame any one for that. I will make something work out, as I have enough confidence in myself and my abilities even at 57. Regards - Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell NJ, 07731 (732) 901-9193 ----- Original Message ----- From: "Sellam Ismail" <foo(a)siconic.com> To: <cctalk(a)classiccmp.org> Sent: Sunday, September 29, 2002 10:34 AM Subject: Re: Hard year to Festival ---- http://www.vintage.org www.VintageTech.com *

Sellam - I agree, completely. I also voted for Perot. But, between Clinton and Bush, at least to me, there is a world of difference.

I still cannot believe that the majority of the American people voted for Clinton, for two terms. I am not claiming that Bush is perfect, but, he is a heck of a lot better in every respect than Clinton, from what I can see, from an engineer's perspective. As someone else pointed out previously, the people that can really do a decent job at being president, unfortunately will not run, or do not have the finances to even get it started if they were to. So, our choices are limited. But, at least, we do have choices. Fortunately in this country, I believe we have the momentum, and the will of the American people, to make things continue, properly, during any administration. Fluctuations in economy and world opinion will continue regardless. I am a consultant, for the military, and as of the new fiscal year I do not have a job. I do not blame any one for that. I will make something work out, as I have enough confidence in myself and my abilities even at 57. Regards - Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell NJ, 07731 (732) 901-9193 ----- Original Message ----- From: "Sellam Ismail" <foo(a)siconic.com> To: <cctalk(a)classiccmp.org> Sent: Sunday, September 29, 2002 10:34 AM Subject: Re: Hard year to Festival ---- http://www.vintage.org www.VintageTech.com *

Ross - I feel sorry for you. Hope your endeavors, in the classic computer collecting hobby, works out, regardless of your misguided beliefs. Regards - Mike

Mike B. Feher, N4FS 89 Arnold Blvd. Howell NJ, 07731 (732) 901-9193 ----- Original Message ----- From: "Ross Archer" <dogbert(a)mindless.com> To: <cctalk(a)classiccmp.org> Sent: Sunday, September 29, 2002 2:10 PM Subject: Re: Hard year Bush, am do this a a I Mike welcome have we > >>should not seek to make ours more honorable. > >> > >>Sellam Ismail Vintage Computer > >> > >> > >Festival > > > > > >>-------------------------------------------------------------------------- > >> > >> > >---- > > > > > >>International Man of Intrigue and Danger > >> > >> > >http://www.vintage.org > > > > > >> * Old computing resources for business and academia at > >> > >> > >www.VintageTech.com * > > > > > >> > >> > > > > > > > > > > > > >

On Fri, 27 Sep 2002, Sellam Ismail wrote: At times like this it is a real shame that they killed the proposed ballot choice of "None of the above" of a few years ago here in California. It wooould be a natural this year!

I was just wondering if any of you have had to drastically cut back on

collecting this year. I collected 20+ Apple II clones in 2001. So far this year, I think that I've picked up maybe six. Collecting old computers is a luxury, of course and this year has been hard on my wallet. I've watched several choice systems go by on ebay, and I never used to let any of them

by -even the crappy ones. Things are getting better for me but I'll sure be damned glad when this lousy year is over. People talk about Black '87 but as far as I'm

'02 has been my "black" year. Ernest http://12.228.5.66

This is getting absurd! Tony Duell wrote: Really? Here we must agree to disagree. Old sockets suck,

generally don't use them for this reason. If I recall correctly, you had to pay extra for sockets (or was that the Imsai??).

> >In fact I would argue you _must_ remove and reseat all socketed chips to >cure bad connections anyway.

This is getting absurd! Tony Duell wrote: I think your failing to address the relative risks here. You may have good reasons for using and reccomending your particular approach to bringing up a vintage machine, but please review the advice the list as a whole has given to this Altair ower: Main filter cap restoration was reccomended without bothering to test if such a risky technique is even needed. This is simply BAD advice, period. Zero safety tests were reccomended, in fact, its not clear from the old messages just what should be done prior t0 applying power for the first time. Disassembly was reccomended to the point of removing chips from boards, despite the lack of documentation. Do you think the list gave this Altair owner good advice? I don't. Really? Here we must agree to disagree. Old sockets suck, and Altairs generally don't use them for this reason. If I recall correctly, you had to pay extra for sockets (or was that the Imsai??). Good for you. Has the Altair owner done this? Do they have the equipment needed for antistatic protection? Hmmm, did anyone tell the Altair owner this Tony? Sure, and pigs sometimes fly, but the FAA is not too concerned over this. Parts can fail for apparently unknown reasons, but is this likley enough that it should determin how an old Altair is brought back to life? Once again, we may have to agree to disagree. Let me get this clear, you would REMOVE soldered-in TO-3 regulators rather than simply check that their case was grounded with an ohm meter? Thats quite some restoration style you have there. Ever restored a machine larger than a microcomputer? The reason why is that the original post was seeking advice on how to safely return an Altair to operation. As you have already agreed, the chances are that ZERO chips need to be changed. How about starting with small steps, and learning new skills as needed? Ahh, so perhaps the most efficient course of action is to take precautions agains messy failures, ones that would burn up etches, etc. Clearly burning up rare chips would also fall under this concept as well, so we have to go back to the relative risks envolved. IMO, having a person new to vintage restoration start by removing chips from boards is FAR more risky than applying power after a few basic tests. The Altair uses +8 unregulated. If this were applies to TTL parts, some ~might~ fail, but you are not going to destroy all of them as you suggest. So once again we are back to the question of how likley is it that such a regulator failure exists in this machine? In your own words, "most likely is _is_ still working". So how then is it any SAFER to reccomend that the original poster start pulling chips off boards? Frankly, I'd risk any chip in the machine to not mess up PCB etches, as many parts (probably) are not in sockets. The advice and discussion have gotten far too abstract, and really are not giving the original poster good advice on how to proceed and what to check for. S-100 vintage decoupling caps generally don't fail I agree, but they are by far the most commonly dammaged components I find on S-100 boards, due to mechanical dammage. They get chiped and broken, often shorting. Other times they break one lead, and short something nearby. The risk here is a burnt etch. Not a huge risk, but given that this risk can be eliminated in seconds with a meter, its not an unwise thing to test, is it? Its been a long time since meters were made that would apply enough current (thats what matters, not the voltage) to dammage devices. Testing the power to ground resistance, even with something like a Simson 260, is not going to cause dammage. Once again it seems the argument is grasping at straws rather than focusing on the original posters needs. Hmm, I'm going to take a board full of old TTL devices, and run them at 8 volts. I'll let you know when they fail. Don't hold your breath though. Yes, it can happen. And if it did happen, there is a chance, not a certainty, that a device might fail. But you have already agreeded that this is most probably NOT going to happen in this case. Given that this is most probably NOT going to happen, the process of removing parts from a machine is far more likley to CAUSE problems than it is to prevent them. Perhaps the best test for the regulators is to leave them alone, given that they probably are working just fine. Aren't you over-reacting to a risk that you admit is unlikely? An extender board with a fuze is a much better idea if you insist on such tests. What that has to do with it is simply this, the list gave the original poster some BAD ADVICE. Your overstating the risks, and the potential for dammage. Then why was the original poster reccomended to 'reform' the caps? Venting is a non-issue? Its really nasty stuff for your health and for the health of the machine, but I agree its not a major risk here. Thats part of why I object to the advice the poster was given by the list. If it takes you a few weeks to power up an old S-100 box, you either have too little time, or your going in way over your head. Once again, good for you Tony. We really are impressed. How many chips has the poster changed? Mainly, is there a really good reason to remove them? This last point may be a matter of opinion for people with experiance, but thats not who the lists replys to the poster should be written for now is it? Risk versus risk. Which risk is greater? The low probability that a regulator has failed, AND that it will dammage other components, or the risk of breaking a pin or the hermetic seal on some vintage chip? Preventitive maintainance is not a repair, an oil change on your car is not a repair. Your grasping at straws here. And this has ZERO to do with an Altair. Apparently one of your 7805's Tony. If you want to make this personal, take it off-list.

"I don't even know what a crowbar is, except that large metal prying tool used to open crates." They're also useful for attempting to bludgeon some sense into individuals that carry on certain threads *far* past their expected lifetime. --John

"I don't even know what a crowbar is, except that large metal prying tool used to open crates." They're also useful for attempting to bludgeon some sense into individuals that carry on certain threads *far* past their expected lifetime. --John -----Original Message----- From: cctalk-admin(a)classiccmp.org [mailto:cctalk-admin@classiccmp.org]On Behalf Of Ron Hudson Sent: Sunday, September 29, 2002 13:36 To: cctalk(a)classiccmp.org Subject: Re: Altair-what do I do first Hey Everyone! Tempers seem to be getting a little heated here. ; ^ ) Thanks for all the great suggestions, Those of you who suggest the technically harder things to do, I am sure, do it out of care for detail and best interest. I have not even gotten the machine yet, I may never. It's from a stranger, (X of a co-worker) who mentioned it once. I will not press the person because I have no real right to the machine. If I do get it, I will probably trade. My knowledge of actuall electronics is somewhat limited, I know what a capacitor is but I can't really identify types on sight. I don't even know what a crowbar is, except that large

prying tool used to open crates.