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Thread: Broken RLV12

  1. #1

    Default Broken RLV12

    My RLV12 controller was broken and the VRLBC0 diagnostic returns errors.
    I want to repair this board but I have no idea to find damaged parts.

    The log of the VRLBC0.BIC is
    Code:
    R VRLBC0
    VRLBC0.BIC
    
    DRSSM-G2
    CVRLB-C-0
    RLV12 DISKLESS
    UNIT IS RLV12, RLV11, OR RL11
    RSTRT ADR 145702
    DR>STA
    
    CHANGE HW (L)  ? Y
    
    # UNITS (D)  ? 1
    
    UNIT 0
    RLV12           (L) Y ?
    BAE ENABLED     (L) Y ?
    CSR ADDRESS     (O)  174400 ?
    VECTOR          (O)  160 ?
    BR LEVEL        (O)  4 ?
    
    CHANGE SW (L)  ? Y
    
    ERROR LIMIT FOR AUTO-DROP  (D)  0 ? 4
    
    ALL REMAINING QUERIES ARE FOR OPTIONAL (MANUFACTURING)
    G5388 TEST-LOOP-MODULE SET-UP.  USE <^Z> TO BYPASS.
    
    G5388 TLM INSTALLED     (L) N ?
    
      MMU AVAILABLE
      MEMORY SIZE   80 KW
      18 BIT ADDRESSING
    
    CVRLB DVC FTL ERR  00136 ON UNIT 00 TST 020 SUB 000 PC: 016356
    MAINTENANCE MODE SEQUENCER FAILED
    AT INTERNAL STATE  2
    REGISTERS        CS      BA      DA      MP      BAE
    BEFORE COMMAND: 000200  004370  000000  066666  000000
    AFTER COMMAND:  112200  004400  000002  110443  000000
    
    CVRLB DVC FTL ERR  00143 ON UNIT 00 TST 026 SUB 001 PC: 017370
    UNEXPECTED CONTROLLER ERRORS
    ERRORS SET: ERR HNF OPI
    REGISTERS        CS      BA      DA      MP      BAE
    BEFORE COMMAND: 000200  004370  155552  001371  000000
    AFTER COMMAND:  112200  004370  155554  020227  000000
    
    CVRLB DVC FTL ERR  00143 ON UNIT 00 TST 026 SUB 001 PC: 017370
    UNEXPECTED CONTROLLER ERRORS
    ERRORS SET: ERR HNF OPI
    REGISTERS        CS      BA      DA      MP      BAE
    BEFORE COMMAND: 000200  004370  133330  001371  000000
    AFTER COMMAND:  112200  004370  133332  020227  000000
    
    CVRLB DVC FTL ERR  00143 ON UNIT 00 TST 026 SUB 001 PC: 017370
    UNEXPECTED CONTROLLER ERRORS
    ERRORS SET: ERR HNF OPI
    REGISTERS        CS      BA      DA      MP      BAE
    BEFORE COMMAND: 000200  004370  066663  001371  000000
    AFTER COMMAND:  112200  004370  066665  020227  000000
    ERROR LIMIT EXCEEDED
    UNIT DROPPED
    
    PASS ABRTD THS UNIT
    CVRLB EOP    1
        4 TOTAL ERRS
    
    DR>EXIT
    I removed 82S181 PROMs (E20-E22) and checked their contents. Checksums of three PROMs are the same as PROMs on working RLV12.

  2. #2

    Default

    If I am interpreting the bits in the CS register (112200) correctly, the 11 is E3-E0 = Parity error abort (PAR ERR)
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    http://www.ricomputermuseum.org

  3. #3

    Default

    Hello m_thompson,

    Quote Originally Posted by m_thompson View Post
    If I am interpreting the bits in the CS register (112200) correctly, the 11 is E3-E0 = Parity error abort (PAR ERR)
    Hmm, my interpretation is
    112200(oct) = 1001010010000000(bin)
    and E3-E0 = 0101.

    So, the error code shows HNF (header not found), I think.

  4. #4

    Default

    Quote Originally Posted by coredump View Post
    Hello m_thompson,



    Hmm, my interpretation is
    112200(oct) = 1001010010000000(bin)
    and E3-E0 = 0101.

    So, the error code shows HNF (header not found), I think.
    Oops, I am used to DEC systems that have a word size that is a multiple of 6 bits.

    HNF would imply that it expected a disk connected and working, or maybe it has a way of simulating the data that would have come from the disk?
    Member of the Rhode Island Computer Museum
    http://www.ricomputermuseum.org

  5. #5
    Join Date
    Mar 2008
    Location
    Westchester County, NY
    Posts
    1,259

    Default

    HNF is correct and should be set. Test 20 is the force HNF with read test.

    I do not see a listing for VRLBC0 available online. I also just checked my fiche, and the most recent listing I have is B0, which is available online. If I was faced with this problem, I would find B0 and run that, then study the test 20 code, maybe studying in particular around the PC address on the error printout.

    I have done a deep dive into the RLV11 some years past fixing a couple of them. The diskless tests run the microcode of maintenance function 0. The RLV11 controller has a beautiful flowchart diagram in the FMPS that steps through the microcode. I wonder if the microcode is at least similar on the RLV12 since the same diagnostic can be used for both. I wish there was the same diagram somewhere for the RLV12.

    Lou

  6. #6

    Default

    The output of this diagnostic isn't very helpful. Usually they show you what they expect vs. what they found.
    On other repair projects I really needed the source for the diagnostic so I could see why it was complaining.
    Member of the Rhode Island Computer Museum
    http://www.ricomputermuseum.org

  7. #7

    Default

    Quote Originally Posted by Lou - N2MIY View Post
    The RLV11 controller has a beautiful flowchart diagram in the FMPS that steps through the microcode.
    Thanks. I read the documents on RLV11 and I understand 'OPI' shows 'error during maintenance command'.

    Unfortunately, I dont' have B0 version of VRLB. I have older disk but it's a subset. It doesn't contain any diagnostic program for RL. Now, I'm looking for the source of B0 version of VRLB.

    Quote Originally Posted by m_thompson View Post
    On other repair projects I really needed the source for the diagnostic so I could see why it was complaining.
    I agree. I'm reading TDM and FMPS of RLV11, but I have not yet found any idea to repair my broken RLV12.

  8. #8

    Default

    Quote Originally Posted by coredump View Post
    I'm reading TDM and FMPS of RLV11, but I have not yet found any idea to repair my broken RLV12.
    On my 8/e, I wrote some very small diags to test for specific issues. They let me test small parts of the board that I though were broken, and gave me a better idea of how the board actually worked.
    Member of the Rhode Island Computer Museum
    http://www.ricomputermuseum.org

  9. #9
    Join Date
    Mar 2008
    Location
    Westchester County, NY
    Posts
    1,259

    Default

    I will mention a strange thing I have noticed on various RLV12s I have worked with over the years. For reasons I don't quite understand, I have needed to turn the C65? (or it may be C66) variable capacitor on the VCO circuit back and forth (returning to where it started), and then the card worked fine. Has anyone else ever noticed this? I should (but haven't) study the mechanical construction of that variable capacitor to see if there is any kind of wiper that has a surface that corrodes. It reminds me of the boards that have Grayhill dip switches that have a corrosion problem, where when you exercise them a few times it wipes the corrosion off the contacts.

    Lou

  10. #10

    Default

    Quote Originally Posted by Lou - N2MIY View Post
    I have needed to turn the C65? (or it may be C66) variable capacitor on the VCO circuit
    I sometimes have the same problem, causing CRC error. But, I think it is not the reason for the problem here.

    If the algorithm of the maintenance mode of RLV12 is the same as that of RLV11, my broken RLV12 can't set WC OFLW at the final stage of the TEST2.

    After E3 (74LS123) pin-5 generates a pulse, E3 pin-4 generates two or three pulses. Then, E3 pin-4 becomes quiet. There is no RLV2 MAX-C H signal. Of course, no RLV2 WC OFLW H signal.
    TEST2_NG.jpg

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