Toshiba e-STUDIO520 Service Manual page 411

2) Irruptive current control circuit
This circuit controls the irruptive current flowing into the current regeneration condensers mounted
on the drive circuits for the motors to a certain value. The circuit consists of a posister (PTH1) which
controls the current and FET (Q12) which supplies the current in normal conditions.
Base current is not supplied to Q2 and it becomes OFF after the RADF open/close switch (SW9)
and jam access cover open/close switch (SW10) are turned OFF till the cathode voltage of ZD3
reaches the zener voltage. At this time, both voltages are set by R36 and C107. Q12 is turned OFF
correspondingly to supply the current to PTH1, and the current regeneration condensers are
charged.
After the current regeneration condensers are fully charged and when the cathode voltage of ZD3
exceeds the zener voltage after the time allowance given by C107 and R36, a base current is sup-
plied to Q2 to turn it ON and Q12 comes ON correspondingly. The current limitation is canceled and
the current flowing in the PTH1 starts to be supplied to Q12.
R66, R67, R68 and R69 are discharge resistors to capture charge stored in the current regeneration
condensers right after either of the RADF open/close switch (SW9) or jam access cover open/close
switch (SW10) is opened. The circuit consisted of PTH2 and D1 captures the charge stored in C107
right after either the RADF open/close switch (SW10) or the jam access cover open/close switch
(SW10) is opened, and also controls incoming current for instantaneous opening/closing of the
cover.
March 2005 © TOSHIBA TEC
Fig.16-95
e-STUDIO520/600/720/850 REVERSING AUTOMATIC DOCUMENT FEEDER (RADF)
16 - 75
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