• Please review our updated Terms and Rules here

Pdp 11/40

Hi John;
Thank You for the clearification, I for now am going to assume, that since the Boards are just sitting in their slots, that plain vibration and or Bad contact to the fingers is causing most of the problems.. I am printing out Lawrences's book and will do some reading and trying out any examples that He gives.. I also need to male a cable for the M7800 board to my PC Computer, running TeraTerm, and see IF I can get ODT to work..
THANK YOU Marty
 
Hi All;
For those who have been away, I did get the system to run a short program, it turned out to be a Bad Cable.. But, according to those who are more knowledgeable than I will ever be.. IT has a Vector Interrupt. I think it is Power AC or Dc LO signal getting spikes when things are running.. What I am trying to figure out is where IC E15 pin 10, is going to, on the Status Board (M7235).. On the right side of the same page, it shows BUS AC LO L coming out of E16 pin 13, which comes from E34, (the 74123) and the input to E15 looks like the same signal BUS AC LO L.. Needless to say I am somewhat confused.. I have the signals AC LO and DC LO coming out of the Backplane Block, pulled High thru a 100 ohm resistor.. I have not attached them to the AC LO and DC LO in the Secondary Block, where the Memory board is, But, after doing the cleaning thing to Both Blocks, (Tomorrow) I will wire them together.. I guess, my main question Is, Is AC LO that I am pulling High the start of the Chain of events, or the end of the chain of events ?? Am I pulling High the right signal, or should it be E15 pin 10, that I need to pull high ?? This has been bothering me all afternoon, so I have not yet gotten to the wiring of the Terminal cable.. Which seems straight forward..
THANK YOU Marty
 
Hi All;
I have cleaned the blocks and tied the second block to the first, for AC LO and DC LO, and tied them with a 330 ohm resistor (seperately) to +5 volts.. No difference, still have Interrupts..
THANK YOU Marty
 
Hi All;
I FOUND THE PROBLEM !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
It was that W2 on the Data Paths Board was NOT Grounded, and it needed to be !!!!!!!!!!!!!!!!!!!!
THANK YOU Marty
 
Hi All;
I found a part, But, the machine is not working.. I am for now only turning it on for short periods of time.. Since I am not completely sure what caused the Burn-out.. It was after I put in the M7800 DL11.. Don't know If that had anything to do with it or not.. The Switches seem to work, but most of the Address led's are on with a few Data led's as well.. I am tracing what All is connected to this chip and where it is going to as well.. Trying to follow who may have been affected.. Both Input and output to the third generation, just in case..
THANK YOU Marty
 
Hi All;
I traced with ohm meter, and wire-wrap boards, (easier to connect meter to) back to the M7800, an 8881.. I still can't say for sure, that the M7800 did it.. But, it looks most likely where the problem origionated.. The system seems to have no clock, per say, which I know is generated by U word.. I need to then trace that back (schematic wise) and see where that origionates.. Trying to figure out If only the timing board is broken, or IF the problem is more wide spread.. I may need to check IC by IC.. One board at a time.. Unless someone has a better suggestion..
THANK YOU Marty
 
Hi All;
I have checked out about a third of the Timing board.. I have alot of Green and Blue dots all over the board.. So far so good.. I had to get out and repair one of my Pulsing probes.. Its the one from Radio Shack, I still like it best of all, my other one is Lp-425 by Elenco..
THANK YOU Marty
 
Hi All;
None of the Boards have IC's that get real hot.. The proms on the U Board get slightly over warm.. And with my 16 pin Led clip over an IC, (I forgot what its really called), it tells me what an IC is doing, not as good as a scope, like for fine detail, but I can get levels.. But, when testing an IC I use my scope, that way I know for sure what is happening.. the Proms are outputting.. That is with just the U board and the Timing board in.. I can see, with my scope that I do have some sort of timing pulse.. Which Is good.. My guess is with all the boards in, something is preventing the timing pulse from continuing.. It gets inhibited..
THANK YOU Marty
 
Hi All;
I have not been working on the Machine for awhile.. I needed to take a break from it all.. I am still sick about what happened.. I am also still trying to figure which way is the best way for me to go.. As I have not heard alot from those of you in the know about PDP 11's.. I can keep going one Ic at a time, gate by gate, it makes me feel like I am not getting anywhere, though.. I can wire-wrap a board, that simulates what the Proms do on the U Board, with Switches and Led's.. Leds for the Address lines, telling me what Micro Address it is at, and Switches for me to put out the (I think) 56 bit word.. Which also allows me to switch on one line at a time, and not all of them.. So, I can check an IC and If it is something like a 74157, I can try it one way and then the other way.. Checking out inputs to the IC as well as outputs.. On the down side it may inhibit any clock signals, on some of the Ic's.. Working my way thru the board.. I could, instead, start with the Data Board, starting with the Switch signals coming from the Front Panel (Console) and working my way thru the Board to the Leds.. I am for now leaning toward making the wire-wrap U Board equivalent.. Any Suggestions and/ or feedback Would be very much appreciated, and possibly lift my spirits.. I know that there are Many of you who have gone thru much worse.. Trying to get an old machine up and running..
THANK YOU Marty
 
I can't really add much but hang in there. I have been busy, have not installed the power supply parts I bought to repair my 11/40. Project has been in limbo for too long.
 
Hi Bill;
Thank You for Your reply, just knowing that people out across the land are rooting for me, helps alot.. What all do you have to do, besides the Power Supply, to get your Machine running ??
THANK YOU Marty
 
Once power is restored it should be functional again. When 15v goes the circuitry protects the logic components, hopefully ayway.
 
Hi Bill;
I wish that would have been the case with my machine.. But, since I didn't have the origional power supply system, I am paying for that difference.. Thank You for your reply..
THANK YOU Marty
 
Hi All;
I have one-third of my 6 wide Blank Board, wired up for connectors to be able to connect to another plain PCB Board. What I have is two 20 pin connectors at the top of the Dec 6 wide board, for each 36 pin connection.. So the Dec board when fully done will have 12, 20 pin connectors at the top of it.. I have four of them done.. Which can then connect to any kind of Board that I want to make, and be used in any slot on the Dec Backplane.. I decided that, that would be the best used of the one full wide Dec (Wire-wrap) PCB board that I have.. Next I can get 12, 20 pin cables, which can be used for connecting to the fake U board, that is next on the list to build..
THANK YOU Marty
 
Hi Lou;
THANK YOU for the information.. I will keep that in mind.. But at first I don't think that it will be a problem, since I will be turning on only one or two bits at a time.. As I will be testing one, possibly two Ic's at a time.. I mainly will be using this to turn on or off usually a couple of the 56 word bits, via switches, and not even running anything at the present time.. It is just a checking out tools, not a running at full speed or even half speed.. Thank You for your Information and your interest.. I appreciate that..
THANK YOU Marty
 
Hi All;
I have finished wiring the Board, so that it has enough 20 pin sockets for the timing board.. But, it will be awhile before I can do this, as I will need to wait until I have enough money for the Cables and the Blank PCB with all the holes, and the wire-wrap sockets.. So it will be awhile before I get the next stage done enough to report something back to you..
THANK YOU Marty
 
You must log in or register to reply here.
Back
Top