SHARP LPE256 Technical Report

Date: Aug. 8, 1996

LASER PRINTER: JX-9200/9210

No. : LPE-256

THE CHANGE CIRCUIT FOR AVOIDING IRREGULAR HEAT.

1.Model Name: JX-9210/JX-9200

2.General: In only rare cases defect could be found in one part of the circuit controller equipped to

prevent the heater from getting out of control, therefore the circuit of the main board
needs to be improve.

3.Cause: When Triac (TD101) becomes under a short circuit by some factor (the thunder surge
etc.) Relay of the heater lamp circuit controller works “ON” and “OFF". If the Relay
ON-OFF repeatedly, the temperature detecting circuit works and the printer stops as
normal error condition or after fuse-blowing but, it is a very rare case, the contact point
of the Relay may be fused.

When contact point of the Relay is fused, the temperature of the heat roller rises untill
temperature fuse F1 (installed in series of the heater lamp circuit) is blown, and smoke
can be emitted.

4.Counter-measure: 1) Temporary countermeasure (For field machine)

To remove off a pair of transistor Q302 and Q303 with using a nipper.
(Take care of that, the lead wire of the transistor on the PWB does not make
short-circuit.)
The same countermeasure as described above would be expected to be taken to all of
the user’s service call.

2) Final countermeasure (For production machine)

To reject the following 6 items.
Q302, Q303, R302, R303, R304, ZD302

Note: There is no trouble with it’s safety when removed off because the this circuit is

provided to avoid blowing of the fuse 2 when CPU gets out of control.

∗ When there is some ticking sound to be listed with user’s machine under the idoling

condition (power on /not printing) that is the sign of the above trouble.
Please consider the on your service call.

SHARP CORPORATION Printer and Scanner Division

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Orange

BA

5.Action: Middle of June 1996.

➀ Each devised product will be red-marked on its produce lot code label.
➁ 2pcs. of screw on the AC input socket of the devised printer will be black-marked.

<Circuit diagram>

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