Hello everyone,

Background

This is my first post so I'll try to provide as much detail as possible so as to respect your time. I'm a hobbyist / tinkerer in my spare time with a background in computer programming. Recently I acquired a confirmed-working BizHub7228 that I've since completely stripped down for part & components.

Steps Taken So Far...


  • I started off by using a multimeter to probe the DCPS blindly; attempting to map out the voltages and groundings coming off the various leads.
  • I couldn't find the 24vdc leads so I started researching possible causes.
  • Tried to lookup the board manufacturer (Matshushita Electronic Components(H.K.) Co., LTD.) and part numbers (27LA84510, ETXKN495ACF, no. 5524V) for any kind of datasheet -- found nothing useful.
  • Tried checked the physical manuals -- found nothing useful.
  • Finally searched online for the printer model and found a "Service Manual" that explains why I couldn't find a 24vdc lead...
    • The SW2 (Sub power switch) is located on the PSW2B (Power SW2 board).
    • Upon the SW2 on, an ON signal is sent from the SW2 to the SCB (System control board) through the OB (Operation board).
    • As a result, the SCB sends a control signal to the DCPS (DC power source),
    • thus causing the DCPS to supply +12VDC, -12VDC (7145 only) and +5VDC to all of the boards and options, including the CB (Main body control board).
    • The SCB (System control board) then sends to the DCPS (DC power source) a control signal
    • that causes the DCPS to generate +24VDC.
    • This 24VDC power is supplied to all of the drive boards and options.
    • (Quote from manual; Format and emphasis mine)

  • I looked back at wiring of the DCPS trying to find a path for this "control signal" to be sent through.
  • My best guess is a bank of leads labeled as such...
    • 3-1 RL CON
    • 3-2 L2 CONT
    • 3-3 L3 CONT
    • 3-4 24V EM
    • 3-5 FM1 EM

  • My next best guess is that "3-1 RL" pin is the right path to send the signal, as RL might be short for "Relay"


The Problem

I can't find a solid definition of "control signal" within any of the manuals I have. I'm not familiar enough with circuit-board-level engineering to really know how to generate the "control signal". My best guess is that the "signal" is a momentary circuit made from one of the SW1 (offline) voltages (12v or 5v) to that "3-1 RL" pin. At this point I really don't want to just start routing voltages to pins I don't understand.

Questions


  • What is a "control signal" as defined in the service manual?
  • Is it possible to emulate/reproduce this "control signal" without the SCB, OB, and PSW2B components being involved?
  • Where should that signal be sent to on the DCPS?
  • Is there a different solution that I should explore instead? (that does not involve the SCB, OB, and PSW2B components)


Additional Resources

The Service Manual and various images of the components can viewed here on dropbox.

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Please let me know if there is any other information I can provide that would help solve my problem.

Thanks in advance for any help.