Epson SEIJ98006 G N D, p i n O S C, EPSON Stylus Color, Revision C, Troubleshooting, Overview

EPSON Stylus Color 900 Revision C

Table 3-19.

Isolating the Faulty Part on the Power Supply Board (continued)

Step	Check Point			Action
9	Is the main switching	Check the electrical continuity of the switching
	FET (Q1) defective?	FET by trying four patterns below. Be sure to pay
		attention to the polarity. If the main switching FET
		is good, the findings should be as shown under the
		figure.
			S t e p S. 1t e p . 2
			G			G
			S		+ D S
			- D	+
						-
			S t e p S. 3t e p . 4
			+G		-G
			- D		+ D
		Step 1: Off, Step 2: On, Step 3: Off, Step 4: Off
10 Is the NPN connection		Check the electrical continuity of the NPN
	transistor defective?	connection transistor on the C265 PSB/SE board
		by trying four patterns below. Be sure to pay
		attention to the polarity. If the NPN contact
		transistor is good, the findings should be as shown
		under the figure. Note the NPN connection
		transistor is shown in the circuit diagram as
		described below.
			S t e p . 1			S t e p . 2
				N P N		T r
			B		B
			E			E
		- C		+	+	C
						-
			S t e p . 3 S t e p . 4
			B		B
		+	E	-		E
			C			C
			-			+
		Step 1: On, Step 2: Off, Step 3: Off, Step 4: On

Table 3-20.

Isolating the Faulty Part on the Power Supply Board (continued)

Step

Check Point

Action

11 Is the PNP connection

Check the PNP connection transistor on the C265

transistor defective?

PSB/SE board in the same manner described in

the previous step.

S t e p

. 1

P

S t

P N

T r

B

B E

B

C

E

E

- C

+

+ C

-

S t e p . 3

S t e

B

B

+

E

-

E

C

C

-

+

Step 1: Off, Step 2: On, Step 3: Off, Step 4: On

12 Is the +5 V regulator

Check the IC51 for the oscillation waveform

(IC51) defective?

(measured by using a oscillo scope) output from

the Pin 5. If the output waveform is as shown

below, it means the IC51 is working properly.

G N D

I C

Os c illa t ion

5 - p i n ( O S C

Troubleshooting Overview 91