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  • MauriceH's Avatar
    August 11th, 2019, 06:03 PM
    MauriceH replied to a thread PDP-11/23 Bootstrap Failure? in DEC
    EK-1T23B-OP-001 PDP11-23-PLUS System Manual.pdf check page 106 -PDF =page 94 book "Microprocessor reconfiguration. Table 8-1 Power-up mode. ...
    8 replies | 717 view(s)
  • MauriceH's Avatar
    August 11th, 2019, 05:39 PM
    MauriceH replied to a thread PDP-11/23 Bootstrap Failure? in DEC
    I mean , you had a working station way back and is now after long time broken. That's what I mean by the first start up seconds after long time off...
    8 replies | 717 view(s)
  • MauriceH's Avatar
    August 11th, 2019, 03:40 AM
    MauriceH replied to a thread PDP-11/23 Bootstrap Failure? in DEC
    So 2 faults? Eprom fault in your system and in his working sytem? That will make a Eprom fault. Then CPU board defect? Did you swap your MMU,...
    8 replies | 717 view(s)
  • MauriceH's Avatar
    August 4th, 2019, 03:45 PM
    Don't let be mislead bij old caps, specially in this kind of really good expensive(way back) engineered products. They put good stuff in them. ...
    14 replies | 1230 view(s)
  • MauriceH's Avatar
    August 4th, 2019, 03:11 PM
    Roland, My TU60 came with 3 cassettes, so maybe something interesting on them.
    12 replies | 584 view(s)
  • MauriceH's Avatar
    August 1st, 2019, 07:25 AM
    MauriceH replied to a thread decserver 700-16 fan problem in DEC
    Could be a heat sensor and then it will only run if internal heat becomes at certain level. Mostly a NTC somewhere on a heat sink. Test with a...
    2 replies | 187 view(s)
  • MauriceH's Avatar
    July 30th, 2019, 10:38 PM
    Ah I see you have a different board. Ok CR409 BLOWN, THen check C486 , Remark a current through a 100k resister will seldom lead to blow a Diode....
    14 replies | 1230 view(s)
  • MauriceH's Avatar
    July 30th, 2019, 10:04 PM
    First check your 12Vdc supply if that is stable. Than check if it is really the center or width problem. Width than both sites left and right...
    14 replies | 1230 view(s)
  • MauriceH's Avatar
    July 23rd, 2019, 11:54 AM
    Have the setting correct? Use local echo (turn it on in the setup menu) so you can visualy see if the keybord is working on the screen. Then...
    5 replies | 298 view(s)
  • MauriceH's Avatar
    July 23rd, 2019, 08:46 AM
    Don, The lesson here is to 10x look close to the schematic with a repair. I also stumbled at first in this part of the circuit by using a LS...
    13 replies | 573 view(s)
  • MauriceH's Avatar
    July 22nd, 2019, 01:41 PM
    Bit schematic. Switch D is data , C is clock. If at the green LED output position you place a switch to pull that to LOW The RED LED will go on....
    13 replies | 573 view(s)
  • MauriceH's Avatar
    July 22nd, 2019, 01:24 PM
    @CHUCK. See attached circuit detail about those 74175.holding quad D-FlipFlops Pin 1 is to Clear the 4 D-FF back to state Q=0, Q'=1 Clock, 4x...
    13 replies | 573 view(s)
  • MauriceH's Avatar
    July 22nd, 2019, 12:47 PM
    Don, Thanks I'll see now indeed I started at 020 instead of 200... Ok ..The order and placement looks ok. Do you not have a serial console...
    13 replies | 573 view(s)
  • MauriceH's Avatar
    July 22nd, 2019, 12:08 PM
    Don,, Many thanks for your reply. Indeed the 74175 are used in a bit unusual way at this frontpanel switch circuit.. That is, it makes in this...
    13 replies | 573 view(s)
  • MauriceH's Avatar
    July 22nd, 2019, 09:59 AM
    I am restoring my PDP8M after a couple of decade s to be a display item... After a PSU repair and some repair at the boards M8330 (Timing Control)...
    13 replies | 573 view(s)
  • MauriceH's Avatar
    July 20th, 2019, 08:15 PM
    I ordered a couple of 100 pin S100 Bus Backplane 0.125' 3.175mm Pitch Card Edge Connector. Should fit also the board thickness of 1,57mm. ...
    6 replies | 460 view(s)
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About MauriceH

Basic Information

About MauriceH
Location:
Dordrecht , Netherlands
Interests:
electronic stuff as old Valve equipment, Old Computer
Occupation:
Service Engineer inland vessel electronics and navigation equipment, as Radar, Pilot, VHF etc.

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August 17th, 2019 01:24 AM
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April 2nd, 2014
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