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questions about 11/83 CPU board, QBUS and card interoperability

I

iainmaoileoin

Experienced Member
Joined
Dec 24, 2014
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216
Location
inverness
I am trying not to let the smoke escape.

I have an 84 [NOT 83!] (KJD11-B M8190 "AE") and memory (NSV11, M8637 "ET") as the 1st 2 slots in an 11/83 9 slot backplane (?number?)
And an M7556 in C/D of slot 3.

I cant get the PSU on this beast to behave (yet). With no cards installed - and a pile of load resistors on the 5v and the +/-15v - I still have a strange waveform on the 5v line. [Not for here].


First.
To test out the CPU board can I take the 11/84 QBUS board out and fit it in a standard 11/73 type QBUS backplane - with it just accessing "normal" memory? Or is that going to cause me electrical grief? I appreciate I will have to work out what the 2 ribbon connectors do, but that wont beat me.

Second
Can I pull out the M7556 and place a "non-memory" 22bit Qbus quad card in place of it (With addresses that dont flight with the unibus which follows the M8191 quad/unibus adaptor?)

Third
Can I use the QBUS slot 3 for a dual height card in A/B? (leaving the grant card in C/D)

Yes I have read the manual. My best guesses are
First: OK
Second: OK
Third: no idea

Comments to help me keep the smoke at bay are welcome.
 
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We REALLY need to know what kind of chassis you are using. What model number is the power supply?

Almost all 9-slot backplanes (where the cards plug in) are straight Q/CD, you don't want a load module installed if the CPU and at least one memory module are installed.

Some of this post seems to indicate you have an 11/84 chassis (qbus cpu and memory, unibus map card, etc.). See the first question, we need to identify the chassis.

I strongly recommend not applying power to the box right now.
 
And WHATEVER you do, get that 7556 unibus load module out of the
Edit:
Never mind, you must have an 11/84 box, which has the load module in slot 3/cd.
 
Last edited:
Photos

Photos

PG31 said:
Is this the type of enclosure that you have?

https://00c8048d-a-62cb3a1a-s-sites...rY9w4Wkkt7a-yxvvmA8ni_fvdmtUg=&attredirects=0
Click to expand...


I will get some photos later today/tomorrow.
OK, don't laugh, check out http://www.scotnet.co.uk/iain/DEC/11-84-1/index.html http://www.scotnet.co.uk/iain/DEC/11-84-1/index.htmlfor the photos straight from my camera. 1/2 of them need deleted, the other 1/2 need to be retaken, but they will give you a clue.
Ah I see my 'scope pictures of the 5volt supply rail are there too. Each photo is in 3 times, once at high res and two reduced size images. One day they will be thumbnails and click through. Right now they are everything in the directory.

My 2 x 84's [not 83s] have "side on" card mounts rather than deep boxes. I have photos but they are not indexed and are awaiting classification.

Before doing anything with the machines I dismembered cleaned, loaded and reassembled both units. The two units are identical. This gave me a great belief that they were viable configurations.

1 powers up - but lacks access to disks at present. The other PSU has a 5 volt rail that dips to 3.X volts every whatnot milli-seconds. I have had the PSU boards out and visually inspected them, measured caps with an in-circuit LCR meter. Nothing obvious hits me - but I am not an analogue engineer - while the theory of switch mode is fine I am damned if I will put any parts of my body within 2 miles of a live circuit to measure voltage! Wimp? Na, I want to live long without too much pain.

H7202B with 5, 15 and 12 volt cards. The only stamp I can see on the chassis is 74-35190-01 REV AX01ML
The backplane has bar-codes on stickies with 54-17228-01 and KA74100212.
 
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The front looks like mine. But on mine the PS is in the back and thus allows the full width of the chassis
for slots.
 
Wild looking system, just about the time I think I have seen a couple PDP-11 systems something like this shows up that I never imagined, a split Qbus Unibus chassis.
I have never seen one or worked with it so don’t know how good my information may be but think if it’s like most high current low voltage supplies that they built back then the incoming AC is feed to a high DC voltage supply that’s distributed to one or more DC to DC inverters that use switching regulators to beat the voltages down to the appropriate level. Pure speculation on my part but if this is the case and you have an issue with the one high voltage supply not developing clean DC to feed the others it will show up as anomalies in all the regulated outputs, much like the 60 or 120 cycle garbage that your scope displays and will also result in a under voltage condition. The primary DC supply will have a fair size transformer, bridge rectifier or maybe diodes and at least one or two huge capacitors that are on the frame and not on a card. Those old capacitors have been known to fail and at their age would be surprised if they still are any good. Don’t know if it’s the case or not and maybe someone who knows can say but going to assume that there is a high voltage DC supply transformer and not a direct AC input switching converter like on newer computers so it may be relatively safe to work on the supply as long as that’s the case but remember that eighty to ninety volts in that supply with a good amount of current is still enough to do serious damage if you are not careful. Also make certain that your scope and meter grounds are connected to the ground rail in the system or you readings and displays will be false.
If that is a direct AC input switching supply you’re better off finding someone with experience working on them including the isolation transformer that it will require for any diagnostic work. High speed switching non isolated power supplies are dangerous and frustrating to work on if you’re not acquainted with their construction and layout.
 
I could not find the horizontal box style in the manual, but I did find a bit that says the M7677 MUST be used when an H7231-E or F is in use.
Neither of my '84s have a M7677 and were otherwise full when I got them.
 
It seems that what you have must be an 11/84-D or 11/84-E with the 9-slot H9277-B backplane instead of 13-slot H9277-A backplane.

According to a post on the classiccmp list back on 2007-05-22:

According to my manuals, there are two backplanes for 11/84
systems. The Users and Maintenance Guide for the 11/84-A ( and -P )
( EK-1184A-MG-001, June 1988 ) shows a 13-slot H9277A, part number
70-20650-01. The Users and Maintenance Guides for the 11/84-D and -E
( EK-1184D-MG-001, EK-1184E-MG-001, June 1988 ) show a 9-slot H9277B, part
number 70-17228-01. But in both cases, the slots below slot 4 are
Unibus. Specifically, for the 9-slot backplane, the slots are listed as

Slot 1 quad width Q22/CD for CPU
Slot 2 quad width Q22/CD for memory
Slot 3 quad width Q22/CD for memory or MLM
Slot 4 hex width special for KTJ11B
Slot 5 hex width Unibus/SPC for hex or quad Unibus device
Slot 6 hex width Unibus/SPC for hex or quad Unibus device
Slot 7 hex width MUD/SPC for hex or quad Unibus device
Slot 8 hex width MUD/SPC for hex or quad Unibus device
Slot 9 hex width Unibus out/SPC for quad Unibus or M7556 MLM

Another difference is that the topmost slot in the H9277A (labelled MDM,
it would be slot 0 rather than slot 1, if they were all numbered) is for
the monitor board. That doesn't seem to be the case in the H9277B,
where the topmost slot is slot 1, for the processor. In both cases,
though, the top slots are quad slots for CPU and memory, and the rest
are hex.

The H9277B is also the backplane used in 11/94-E systems.
Click to expand...

I can't find any online copies of the EK-1184D-MG-001 or EK-1184E-MG-001 manuals.
 
gslick said:
It seems that what you have must be an 11/84-D or 11/84-E with the 9-slot H9277-B backplane instead of 13-slot H9277-A backplane.

According to a post on the classiccmp list back on 2007-05-22:



I can't find any online copies of the EK-1184D-MG-001 or EK-1184E-MG-001 manuals.
Click to expand...

I have a hard copy of EK-1184E-MG-002 and EK-1184E-TM-001 which match the 11/84 I have.
 
Thanks for identifying that kit.

Now back to my questions about trying to keep the smoke at bay-
Can I fit the 11/84 CPU into any 2bit Qbus backplane to allow me to test it out?
Can I put a qbus dual card into slot 3 (the one that says MLM) ? If so what do I put into the C/D area (or can I leave the load module in place?)
Can I put a qbus quad card into slot 3
Thanks
 
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