HP 2116B rescued - two boards missing :-(

[pbirkel@gmail.com]

I think I see what you mean. I think you mean the system level. The PSU as one single unit which (hopefully) has a detailed spec. One can maybe workout a spec on the basis of the functional description and some curves that show sequencing and tables of voltage tolerances. Perhaps.

My intention from the beginning was to replace as little as possible. Just the regulator boards which control the series pass transistors. The transformer, the bulk capacitors, the output smoothing capacitors, the series pass transistors and crowbar are left as is. Just the regulator module is going to be replaced somehow. If I get hold of the regulator boards that are missing I just put them in place and go. Thus my interface with the world is what surround these two cards. And then a lot of the requirements come from various design decision they made back then. For example: we have Ge-transistors (Q33), lets make them the current limit sense circuitry by having a 0.2V drop over the sense resistor when they start to conduct or use a Ge -transistor (Q34) with some diodes to create the power sequencing that doesn't allow +4.5V until -2V has reached correct level.

Since I am not intending to replace the current sense resistor or the Ge pass transistors at at this point I need create something that correctly interfaces all those things. I don't think I can find a HP spec for that on the unit level. Perhaps they have a detailed system level spec (not sure about that either - a lot is just implied by the schematic).

I answered the more general-case question, not your specific use-case. Mea culpa. However following the same path I'd ask whether you could get suitable instrumentation-data from an operational HP2116B or borrow a module that you could use to obtain such data yourself in order to reverse-engineer the boundary/interface requirements on each regulator board. Not that I have one to offer, but it's an approach to consider. Send out a call for known HP2116B units?

On the other hand if I do start to replace various parts exterior to the regulator board, like replacing all the pass transistors with modern PMOS parts (which I gave some thought initially - before I concluded that it was possible to find 2N2156) , I will be on the slippery slope towards replace everything with Chinese switchers.

So ... I think that you've come to the point of answering your original question with "exact replica" because there's apparently no other way to discern/divine the interface requirements other than setting up a SPICE simulation wherever it becomes necessary to substitute a different part than in the original schematic. You'll certainly learn an awful lot about the design that way :-}.

And actually I sort of would like to open it up and show the quality of the HP design and engineering which is something special compared to DEC or a flimsy DG.

IMO the nature of the three sorts of PS designs reflects the corporate objectives/experience. At that point in time HP was essentially a company of analog instrumentation engineers, so PS design was simply another exercise in quality analog design and gold-plated (literally) PCBs. DEC sprang from a principally digital design community; their PS designs were generally robust and mechanically well-engineered but nothing exceptional. DG was founded on the premise that corner-cutting in all aspects of design/implementation was necessary in order to achieve a cost/performance ratio that would yield success in breaking into the OEM market that DEC already held. Their PS designs reflected those concerns. It's amazing how many and how often field modifications happened throughout the early Nova-line systems. One could even declare that they pioneered the (later) Microsoft V1.0 software scenario where getting a product into the field for feedback and rapid modification was the whole point. Their field engineers must have had a lot of "fun" keeping systems operational and well-patched in the early years. Today we have other catch-phrases for the same philosophy :-}.

 

[jlang]

That's a really good deal. Even if you don't currently need the boards.

 

[Terri Kennedy]

I answered the more general-case question, not your specific use-case. Mea culpa. However following the same path I'd ask whether you could get suitable instrumentation-data from an operational HP2116B or borrow a module that you could use to obtain such data yourself in order to reverse-engineer the boundary/interface requirements on each regulator board. Not that I have one to offer, but it's an approach to consider. Send out a call for known HP2116B units?

At the LSSM we have some HP systems of that era (HP used a variety of processors to make the various HP 2000x Time-Shared Basic systems). The next time I'm there I'd be glad to look at the systems on the display floor and in off-site storage and take high-resolution photos of the boards that are needed, if our systems use them.

Stockholm is a bit far from New Kensington (near Pittsburgh), even though I'd like to visit with boards and help get the system going.

 

[MattisLind]

At the LSSM we have some HP systems of that era (HP used a variety of processors to make the various HP 2000x Time-Shared Basic systems). The next time I'm there I'd be glad to look at the systems on the display floor and in off-site storage and take high-resolution photos of the boards that are needed, if our systems use them.

Stockholm is a bit far from New Kensington (near Pittsburgh), even though I'd like to visit with boards and help get the system going.

Yes, please. Good photos could be very useful. Maybe LSSM happens to have spare boards that they don't have immediate need for? I am willing to trade for some other 2116 board that I have.

Yes, it is quite far away... But if you have somehow are going on a trip to Europe you are most welcome. My stuff is located 100 km west of Stocholm in the rural area of Södermanland, the island Aspö in the middle of lake Mälaren.

 

[MiaM]

Also: It's located at a place that shares it's name with a way larger (population size) in Scania, a totally different part of Sweden

 

[MattisLind]

The small regulator boards that are missing are looking like this (in case anyone happen to see one...)

 

[MiaM]

Looks like it would be possible to create rather realistic replicas just from those photos alone.

 

[1944GPW]

I think you can see those two boards flicking by in this animation, click and drag to view frames https://www.hpmemoryproject.org/present/contribution/anim_2116a_01.htm

 

[MattisLind]

I managed to buy another set of boards from the same seller. This time I wasn't that lucky geting a really good price. There were another bidder. Looking at what that bidder had recently bought it was quite clear it was a gold hunter. A lot of won auction in categories like gold and scrap metal. Anyway I got them and saved them from being ground into gold dust.



However there were one board that stood out: The 12588-6001 power fail with auto restart board. That was a board that I could in my machine since the standard power fail board can be replaced with such a board. Fantastic!


When I had won that auction I browsed Ebay and found a binder of HP manual which contained the service manual and diagnostic for the 12588A board.


So now I am bit closer to have a working machine and I have quite a lot of spare parts and odd controllers for disks like 2770 or 2771.

 

[Terri Kennedy]

Yes, please. Good photos could be very useful. Maybe LSSM happens to have spare boards that they don't have immediate need for? I am willing to trade for some other 2116 board that I have.

Yes, it is quite far away... But if you have somehow are going on a trip to Europe you are most welcome. My stuff is located 100 km west of Stocholm in the rural area of Södermanland, the island Aspö in the middle of lake Mälaren.

I don't get out to the museum that often, so email them (address available via the Museum's web site to prevent email-harvesting spambots) and ask for pictures (feel free to mention my name).

As far as sending boards, many years ago, I sent an 8650 board set to @bqt in Sweden and they vanished. And that's back when those boards were not unobtainium. So I think there would be some reluctance to do that.

 

[MattisLind]

Here are scans of the documents that I bought that as far as I know is not online:

HP-12588-9002_Power_Failure_Interrupt_With_Automatic_Restart_Computer_Acessory_Kit_Operating_And_Service_Manual
HP-13210-90004_Cartridge_Disc_Memory_Diagnostic_7900_7901_13210
HP-02116-91769_Power_Fail_With_Automatic_Restart_Test

So both the service manual with the schematic and the diagnostic manual for the card. The also a diagnostic manual for the for the 7900 drive and controller.