Brother HL-3450CN Service Manual page 120

(2) Connector Pin Assignment
1) DCN2: IOD1 PWB - Power Supply Unit ACN1 (28 pins)
Pin No. Signal
1 +5v - 1
3 +5v - 1
5 +5v - D
7 +5v - D
9 ACSYNC - N
11 +24
13 +5v - 1R
15 HON - N
17 +24v - 1
19 +24v - 1
21 +24v - 1
23 +24v - 1
25 PGND
27 PGND
2) DCN17: IOD1 PWB - High Voltage Unit (18 pins)
Pin No. Signal
1 +24v - 1
3 FUTEMP
5 ACVON - N
7 CHVON - N
9 CBVPWM - N
11 DBV (MC) PWM - N
13 DBV (KY) PWM - N
15 FCBVPWM - N
17 AC_DCON-N
3) DCN3: For Factory Use Only (4 pins)
Pin No. Signal
1 TESTO1
2 TESTI1
3 TESTO2
4 TESTI1
4) DCN5: IOD1 PWB
Pin No. Signal
1 REARDOPEN - P
2 NC
3 TOPDOPEN - P
Pin No. Signal
2 DCOFF2-P
4 SGND
6 SGND
8 SGND
10 SGND
12 DCOFF1 - P
14 ACOFF - P
16 TESTI2
18 TESTO2
20 TESTI1
22 TESTO1
24 PGND
26 PGND
28 PGND
Pin No. Signal
2 PGND
4 PGND
6 PWMON - N
8 CHVERR
10 THVRON - N
12 THVPWM - N
14 THV - I
16 TH1
18 TH2
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HL-3450CN SERVICE MANUAL