The SPERRY UNIVAC UTS 40 system + 8406 double-sided diskette subsystem : Restoration

Dominique Carlier dce at
Wed Oct 4 06:34:51 CDT 2017

Hi All !

I started checking / replacing all the capacitors - tantalum and 
electrolytic - on the CPU board saved from the US. Until now I don't 
found the guilty.
The CPU board of the USA is a horror to troubleshoot, because of the 
acid the battery that changed the nature of solder tin and some kind of 
resin characteristic of these PCBs, it is difficult to desolder the 
components. I wonder if I would do better to repair my own CPU board 
because this one is finally in a better state in comparison.

What is raging is that these two types of breakdownswere perfectly well 
identified by Sperry Univac. According to the UTS 20 manual :

- Blank screen and long tone (the breakdown of my CPU board) : I'm 
supposed to report this information to my Sperry Univac customer 
services, point, no explanation

- SERIAL I/O CHANNEL B failure (the breakdown of the CPU board from US) :
Their advice = Corrective action: none, and I'm supposed to transmit the 
code "3560U-0010" (still to my Sperry Univac customer services).

Zero information, nothing, it is raging. One or two clues to orient my 
research would be so precious...

I have the corresponding manual but for the UTS 40 somewhere lost in my 
attic. I will find it, I do not have the hope to find a better 
description but I must be sure.
On this subject, I would like to scan and share it because it does not 
exist on the internet.


On 2/10/2017 18:13, Dominique Carlier via cctalk wrote:
> Hi everybody,
> Here is the next episode of the restoration of my UTS 40.
> During the previous “season”, I was talking about buying a wreck of an 
> UTS 40 from the USA.
>  I had taken the risk to buy it, after the conclusion of the sale, the 
> seller had retracted, I had argued with him, I finally put a bad note 
> on Ebay. However, surprise! The guy still sends me the machine. This 
> one remains blocked during a full month at the Belgian custom house. I 
> finally receive it, and now, if you like horror movies, you will be 
> happy.
> Here is the state in which I received the machine:
> I never - never! - received a package in this condition !! The reason 
> maybe was the hideous and ridiculously “protective” packaging ? 
> Possible ... or in the plane they 400kg over my UTS ? Possible ... but 
> we still have the impression that someone hammered the machine, even 
> the very solid plastic pieces have also shattered.
> As I am an optimistic guy, I think "the plastic ... not important, 
> fortunately the chassis and the electronics of this machine is build 
> like a tank".
> I analyze the boards, as expected, some architectural differences but 
> not so much. Here is the CPU board:
> Unsurprisingly, the battery has sunk and there are damages:
> With courage I clean the board, I replace some resistors, one 
> capacitor, ...
> Before/After
> and I replace the battery (2,4V ? A doubt persist)
> And comes the time of the first test and it boot!
> The POC test at startup is not successfull but from the outset, this 
> allows me to analyze and diagnose some elements of my own UTS 40, here 
> is what I notice:
> - The program cartridge of my UTS 40 is functional
> - The power supply to my UTS 40 is OK
> - The video circuit of my UTS is OK
> - The keyboard of my UTS requires a restoration (aluminum discs, foam 
> cylinder, classic issue of old keytronic keyboard)
> - The absence of the backup battery is not a problem, the machine can 
> boot, without this it can successfully passing the POC test and the 
> encoding of the parameters in the setup page is possible.
> I discover other interesting things about the relationship between the 
> cartridge program and the hardware configuration.
> - These program cartridge are made for a specific hardware 
> configuration, for example the RAM repartitions at the level of 
> hardware has an impact on the result of the startup test. The number 
> of kilobytes checked, the memory extension considered as PASSED or 
> FAILED. Even the installed memory is working and assignable, with a 
> configuration that differs from the hardware intended to run with a 
> specific Program Cartridge, the POC test could show that a memory is 
> missing, simply because the RAM is not physically in the slot or 
> socket according to the program specification in the cartridge.
> I drew this conclusion because the CPU board form USA has 64Kb 
> installed on it, and 27 empty sockets, I filled them with RAM and now 
> with the program cartridge form Ebay, 4X  64KB are detected and 
> flagged with a PASSED.
> However with my program cartridge, it detects a second memory 
> extension as PASSED, but considers the first extension FAILED, I think 
> that on the original CPU board, there was only 32kb, even 16kb and 
> non-extensible on that board (hence the presence of two memory 
> expansion boards in my original configuration). Briefly, according to 
> the inserted program cartridge, the tests are sometimes but not always 
> dynamically adaptable to a given configuration.
> - A cartridge program can be programmed to operate only with a 
> specific model of PERIPHERAL I/O board. The program cartridge form 
> Ebay does not work with my PERIPHERAL I/O board, however my program 
> cartridge seems to detect the PERIPHERAL I/O board of the US.
> - I recreated the breakdown of my machine with the hardware of the 
> other UTS. I'm talking about the situation of a long BEEP + blank 
> screen, this happens if I remove the unique memory expansion board in 
> the original configuration of the UTS from Ebay, this could mean that 
> my own CPU board is maybe OK and that this could be one of two memory 
> extensions of my machine that has a problem (Hypothesis).
> But now, without documentations, without diagrams and schematics, 
> without info, I'm blocked on a problem, at the beginning it was 
> intermittent, now it's constant, and even aggravated, the explanation:
> Here is the best result I could get with the following configuration: 
> CPU board form US + my PERIPHERAL I / O board + memory extension from US
> The POC test is successful, it loads the default settings in non 
> volatile RAM:
> And I can access the setup page:
> Everything would be perfectly fine if most of the time I did not have 
> at startup an error at line 9. of the POC test:
> This error blocks the machine, it does not load the default settings, 
> I no longer have access to the setup page.
> I continued to clean the board, looked for damage related to corrosion 
> of the CPU board because of the battery, but today it is not better, 
> it stops at line 8 of the POC TEST:
> However, it could be inferred that this is because the machine can no 
> longer determine whether the status of the SERIAL I / O CHANNEL B is 
> Last thing, the few times I was able to go into the setup page, I 
> rushed to try to encode (with the dead keyboard) the information to 
> declare the subsystem and finally return to the CP/M mode. And I had 
> twice the fig case where busy to enter the data, without warning hop! 
> Blank screen, reset, POC TEST -> SERIAL I / O CHANNEL B: FAILED
> We have here some interesting information about the intermittent 
> nature of the failure, could this give information about the type of 
> component in default?
> So I have not yet been able to return to the CP/M mode.
> My questions are:
> - What exactly is "SERIAL I/O CHANNEL B" in this machine?
> - What components are used by this SERIAL I/O CHANNEL B?
> - Is there really no way to find the schematics of that CPU board? Or 
> better, the complete machine, including the PSU?
> I think that if I can fix that problem, I could go back to the setup 
> page and restart the machine in CP/M mode, in fact it is the last 
> obstacle, if I solve this problem my machine is fixed.
> Thanks in advance for your help !
> Dominique

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