9810 on TAS



#27

Hm. HP 9810A calc, $599 Buy It Now, but seller hasn't plugged it in "for fear of blowing something".

Expensive bet. Still, tempting. Would have jumped already if not for the $ spent on the SR-60.


#28

Well, it's Buy it Now or Best Offer, so why not just make an offer ? Also, they have a 7 day return policy, so you don't need to be stuck with a lemon.


#29

Mmm...good points. I'll make an offer...

After having my collecting bug re-ignited recently, I've added an HP-85, HP-87, several HPIB disk drives, and the SR-60 to my existing desktop collection of an HP-46, a 9815, and a 9825 (which I just had Larry Atherton refurb the tape drive and printer on).

I am running out of space for these large machines. Perhaps I'll sell the 9815; it works perfectly, but the printer sounds like a machine gun and I've always been annoyed that you can't see your program on the display.


#30

Quote:
I am running out of space for these large machines.

The only large machine I have is an HP 46, which completes the scientific trilogy of HP 45, 46 and 91, and that's all I can handle spacewise. It would be nice to also have an HP 81 to complete the financial trilogy of HP 80, 81 and 92, but unless I move to a larger home it's not in the cards. The only calcs I buy nowadays are handhelds.


#31

Yeah, my original collection was "handheld scientifics", but I have all of those, collected over about 30 years.

They accepted my "best offer", so the 9810's mine. Any suggestions anyone might have about what I should do before putting power to it would be appreciated. I believe the standard is to open it up, remove all the plug-in cards, and clean the contacts thereof...but I'm sure there's more.


#32

Depends a bit on what test equipment you have.

If it was mine, I would:

open it up, disconnect everything from the power supply (if possible)

Clean out any dead bugs, spider webs, mice droppings, etc. Check for corrosion and any obvious scorch marks

Check the continuity of the power supply INPUT (check across the power plug with an ohm meter), with power switch in both ON and OFF position - checks for shorts and blown fuses or power supply transformer

Plug it in (hold your breath)

If nothing blows up, check the power supply output(s) for the expected voltages. If you have a 'scope, check the DC voltages for AC ripple (or use your multimeter in AC mode on the DC lines). A likely problem, if has been sitting for a long time, is that the electrolytic filter capacitors for the DC output have gone south. They should be relatively easy to replace if necessary.

At that point, it ought to be safe to plug various things back into their slots with power connected

Good luck!


#33

Thanks for the tips, Dave. I do have a multimeter so I can perform the basic checks you mentioned. I'll post my results here.


#34

Congratulations! You may want to have a look at my 9810 ownership experience. It's a gorgeous machine, but it might require some work.

My 9810 repair job

Regards
Andreas


#35

Interesting information. Using a soldering iron and a multimeter are pretty much the limit of my hardware abilities, so if the machine's dead, I'll have to decide whether to return it or appeal to the community for (paid) help.


#36

Hey Dave,

I have a recently picked up a 9810 from a Hospital near Philly. I have to debug a keyboard problem, then rebuilt & repair the printer and card reader.

If you're interested, we can embark on the troubleshooting together. Tony Duell in the UK has already helped me A LOT.

BTW, I was "wicked brave" as they say in Maine (or stupid) and plugged this on in and turned it right on. After some funcky behavior it seems to work okay except for the keyboard.


#37

I appreciate the vote of confidence, but I think any help you can get from Tony will be several orders of magnitude more useful than I can offer!

My comments are pretty generic for starting up any old piece of electronics, whereas Tony has been all over the insides of these.


#38

I'll be happy to help anyone get one of these machines running again (ditto for the 9820 and 9830, I can't comment as much on the 9821).

I have to be honest, they are not trivial machines to get going in some cases. On the other hand if you do have a nasty logic fault, you will learn a lot tracking it down.

Then there are mechanical repairs. The card reader roller will certainly need replacing, the printer platen may be decayed too. There are various ways to repair these, I can tell you what I do (and there are some pictures in my flickr account, tony_duell, listed as for the 9820 printer and card reader, the 9810 is the same), but as you'll see from there I have a reasonable workshop.

I hate to blow my own trumpet even more, but I've submitted 8 articles on repairing these machines to HPCC (to go in Datafile). At the moment I am not willing to share said articles (to et them you have to join HPCC), I may well do so in a couple of years time after they are all published. FWIW, the first 5 articles are simply on how the machine should work, understand that and IMHO finding the fault is easy!


#39

Quote:
I hate to blow my own trumpet even more, but I've submitted 8 articles on repairing these machines to HPCC (to go in Datafile). At the moment I am not willing to share said articles (to et them you have to join HPCC), I may well do so in a couple of years time after they are all published. FWIW, the first 5 articles are simply on how the machine should work, understand that and IMHO finding the fault is easy!

Were I to join HPCC (which I must admit I was unaware of until now), are all of your articles available, or are some still pending?

It seems virtually none of the Datafile content is available online, which strikes me as odd and counterproductive in 2011. Even HP makes all of their HP Journal content available online.

I have no problem buying a membership, though. God knows it will be less than I paid the Computer History Museum to scan those SR-60 manuals.


#40

How many people would subscribe to Datafile if all its content was available free online? HP didn't have to worry about that sort of thing when they put HP Journal online (and gave out paper copies for free back in the day).


#41

I wasn't suggesting that the content be free, merely that it be available online. It's not as if write the code to implement name and password authorization-- like, say, we do here on this forum-- is particularly difficult.


#42

This has been discussed at HPCC many times. I think it comes down to several issues

-- What is to stop people sharing their password, or distributing the downloaded documents? In other words, a group of people get together, one joins HPCC, and the on-line issue of Datafile gets to all of them. Yes, I realise you can pass round a paper copy too, but it's a lot harder to duplicate it, there's a big difference IMHO between showing a magazine to a friend and giving him a duplicate of it

-- There is no requirement for members to have internet access, ability to view or print files, etc. And I happen to know that a number of members do not in fact have such facilites. We would have to keep the printed version or risk losing some active members.

-- This would then lead to multiple classes of membership which would be more work for the club.

-- It would proasbly have an impact of the sale of Jake's CD-ROMs, which are also a source of income to the club.

But I am not really the person to talk about this. Feel free to pester the other committee members (details on the hpcc web site).

#43

Most are still pending...

Part 1 : CPU Theory was published in the last issue of Datafile (HPCC journal). Part 2 : HP9810/HP9820 memory theory should appear in the next issue, when it gets produced (It's currently about 2 months late!).

The remaining parts from memory are : Part 3 : HP9830 memroy theory; Part 4 : Display, Keyboard and Printer theory; Part 5 : Storage and PSU theory; Part 6 : Dismantling and initial checks; Part 7 : Electronic troubleshooting; Part 8 : Mechanical repairs.

I am not really the person to comment as to why Datafile is not available on-line. I guess the main reason is that HPCC is a club, not a big company, and we rely on income from membership fees for club expenses. Of course none of the people involved in the club are paid in any way for their work.

Authors of articles do not transfer the copyright to HPCC, they do however grant that HPCC may publish the articles and normally that they may be included in other HPCC and related publications (such as Jake's CD-ROMs of datafile). Authors are therefore welcome to publish their articles online (or on paper) if they so wish. My moral view is that I will not do this during the year that HPCC publishes them in Datafile (and maybe not for at least one more year), after that I would be prepared to make my stuff available.

#44

I hate to say this, but as it's a bit-serial machine, I know that _I_ would have a lot of difficulty fixing logic faults with just a multimeter.

I find I need 3 things to do serious troubleshooting on these machines :

The schematics (available from the Australian museum site)
A logic analyser
CPU Microcode source listing (ask me nicely...)


#45

Quote:
I hate to say this, but as it's a bit-serial machine, I know that _I_ would have a lot of difficulty fixing logic faults with just a multimeter.

I find I need 3 things to do serious troubleshooting on these machines :

The schematics (available from the Australian museum site)
A logic analyser
CPU Microcode source listing (ask me nicely...)


Actually, I'd have a lot of difficulty tracking logic errors in a 9810 even with an entire lab full of professional equipment, since I don't have the knowledge to use it.

Purely mechanical repairs like card reader rollers are one thing (although this may largely be academic since I don't have any 9810 cards. Perhaps I can cut an SR-60 card down to fit); programming, which I am actually quite good at, is another; but hardware work at this level...well...

I will do the obvious stuff already mentioned, and perhaps it will Just Work. It's not unprecedented. If it doesn't, I'll comfort myself with the fact that there are knowledgeable folks here willing to help.


#46

Yes, you are absolutely correct. I have said many times that the most important piece of test gear is your brain :-)

More seriously, all the multimeter, logic analyser, 'scope, etc do is enable you to gather evidence as to what the machine is doing. You can't directly see electrical signals, and you can't directly interpret any signal at 8MHz, so you need test gear to be able to follow what the signals are doing.

However, IMHO the _only_ way to find a fault goes like this : Understand what the machine should be doing, make measurements to find out what it is doing, then work out why the 2 are different.

This may be straightforward (for example if you're missing some segments in one row of the display, I'd home in on the driver chips for that row), it may be complicated (a totally blank display can be caused by a fault in the CPU, memory, PSU, display driver, etc). But only by goinging logically through the machine will you find the fault and cure it.

Making random changes, boardswapping and the like, will get you nowhere fast.


#47

I'd like to add that the 74LS688-based address comparator we used to track down the current uCode address on my 9810 might be a worth a try, if you do not have a logic analyzer. I don't have one either, although it's on my wishlist for quite some time.

#48

Well, if it were a modern machine, it'd be easy: I have more motherboards, processors, memory, video cards, cases, and power supplies than I know what to do with (I test hardware for a reviews web site). I can (and have) swapped stuff out to isolate problems, and I've been in the computer industry since the late 70s and so can generally zero in on a problem quickly.

At least many of the 74-series ICs in the 9810 are still available, unlike, say, the special TI chips in an SR-60.


#49

It's true that most of the chips are still available. I recall that one owner had problems with a triple or quadruple logic gate, and had to build an equivalent circuit with two smaller gates. When I did my repair job, I bought most of the 74 circuits required, to be ready for futur service needs. I think the most difficult tasks on this type of machine concern mechanical parts; unlike Tony, I do not have a lathe, but I am considering getting one.


#50

I quite agree, that's one of the nice things in these early machines.

The 9815 is also built from standard linear and 74LSxx chips. The only exception is the masked ROMS, but in later units (and in the 9815S), these can be replaced with standard EPROMs which are pin-for-pin compatible with the original chips.

Of course, as sales volumes increased, it made economic sense for HP to produce custom chips, which also resulted in pocket-sized calculators!

Joel Setton


#51

Quote:
Of course, as sales volumes increased, it made economic sense for HP to produce custom chips, which also resulted in pocket-sized calculators!

The HP-9800 series is contemporary with the HP-35 (1972), so I doubt there was any linear progression from HP's desktops to HP's handhelds.

At Georgia Tech so long ago (1972, 73), an HP-9820A was used to control a digital circuit simulator. It connected to a panel that accepted special jumper-plug boards that were similar to the 1940s/50s-era programming boards used in some early computers. On this board various types and number of logic gates were represented which students would connect appropriately with jumpers to configure and test their solution to assigned digital design problems. I really liked the 9820A, which could be also be diverted to normal calculator use. I still have a couple of its magnetic program cards. I don't recall what I had programmed on them, because the associated thermal paper listings faded a few years after printout.

In the mid-1990s, I was given an excellent condition but (of course) non-working HP-9820A that powers up but does little else. I've not tried any troubleshooting due to higher priority projects. Still, it has nostalgic value as an example of the first HP that I ever used. (The HP-35 and -45 were in the college bookstore at the time, but I could never have afforded one.)

(Edited to correct my 9200A typo in the last paragraph to 9820A.)


Edited: 2 July 2011, 6:06 p.m. after one or more responses were posted

#52

You can easily 'disconnect everything from the power supply' The power supply regulators are on the 3 PCBs under the metal plate at the right side of the machine. The mains transformer is on the rear panel, and the secondary (output) windings are wired to edge connectors on the base of the machine. The PSU boards plug both into those and into edge connectors on the main backplane.

So if you remove the PSU boards you can apply mains and test the mains trasformer. If you remove all the other parts from the backplane (memory box, CPU boards, display, printer, card reader controller, keyboard signal cable) you can fit the PSU boards, power up and check that the power supply outputs are all correct.

Most of them are avaialable on testpoints on the PSU boards (labelled on the metal cover plate). The 5V line isn't, but you can easily fidn that on one of the edge conenctors. The chassis is connected to the machine's 0V rail and you can connect the -ve multimeter probe there.

The mains on/off switch is, of course, on the keyboard assembly. It's connected by the 5 pin in-line connector. Unless that is connected, you can't power anything up. Be careful not to touch the connections on the back of this switch, it's live mains!

The cooling fan is connected to the primary (mains) side of the transformer. If that's running, you know that power is getting that far, but nothing more.

Don't forget to check (and if necessary reset) the voltage selector switches on the back before appling mains. Burning out the power transformer will ruin your day.


Possibly Related Threads...
Thread Author Replies Views Last Post
  OT and TAS related, but ... What Unisonic Models are shown in this auction picture? Gene Wright 6 751 07-04-2012, 12:53 PM
Last Post: Guenter Schink
  TAS Modules - which are 4K ? Gene Wright 2 408 07-01-2012, 07:58 AM
Last Post: gene wright
  Has anone seen the 'other' TAS? Matt Agajanian 8 744 05-03-2012, 08:08 AM
Last Post: Luiz C. Vieira (Brazil)
  Buying in TAS outside US Fabricio 14 1,158 04-14-2012, 08:51 PM
Last Post: Fabricio
  OT: FYI...Red dot HP 35 with rom bug on TAS Gene Wright 7 658 01-06-2012, 07:19 PM
Last Post: Michael de Estrada
  Vintage HP71B Calculator HP 71B RARE CLEAR CASE! in TAS robertoataulfo 4 598 12-19-2011, 11:43 PM
Last Post: Keith Midson
  I think it is my HP71B (TAS) Miguel Toro 11 912 12-06-2011, 02:56 PM
Last Post: geoff quickfall
  Question about Hungarian Sellers on TAS Namir 22 1,663 11-07-2011, 05:28 AM
Last Post: Bart (UK)
  Another Red Dot on TAS. Is it or is it not ? Michael de Estrada 8 764 11-02-2011, 03:44 AM
Last Post: Michael Eckstein
  Who Needs TAS When We Have Samson Cables? Les Wright 13 1,079 09-28-2011, 04:42 AM
Last Post: Roger Blake

Forum Jump: