Xerox Phaser 3450 Service Manual page 155

CIRCUIT DESCRIPTION
11.4.4 Environment
THV voltage recognizes the change in the transfer roller environment and then supplies optimum voltage for the
environment to create optimum image. Analog data is converted to digital by the environment sensor of the transfer roller.
According to such digital output stored in the program in the engine controller Rom, and with the consideration of the paper
type printing environment, optimum transfer voltage is supplied.
The environment recognition setting for the ML-6000 series is as following.
First set the THV(+) standard voltage. Then, set the 800V standard voltage by using VR201, which has 200ß supplied in
the output section. Next, set the standard CPU index value to 80 using VR302. This is to set the CPU standard of feedback
current to 8ßÀ when the output voltage is 800V and resistance is 100ß. If dif ference resistance value appear at 800V, the
feedback current and the index value will also vary accordingly. Based on the index value read by CPU and already set
Transfer Table, the corresponding transfer voltage is generated. The change in transfer output required in each section is
adjusted by PWM-DUTY.
5V
R201
10K
THV-PWM
3 4 5 6
CN2-#5
U2-C
U2-B
7407 7407
24VS
+
C101
35V 47uF
5V
CN1-#3,4
18V
R3
1/2W 560
THV-EA
1 2
U2-A
CN2-#7
7407
D-GND
THV-READ
R316
CN2-#6
1KF
R317
2KF
Service Manual
11-24
18V
R206
100
R208
30KF
R205
Q203
1K
A708-Y
R209
R207
100KF
2K C201
103
C202
331 R210
VR201
845KF
50K
ZD1
5.6V
C7
104
24VS
D301
1N4148
C4
104
10
+
8
R303
R302
9
- 33K 100KF
U1-C
KA324
C303
333
C302
R301 D302
102
1N4148
470K
C301
222
24VS
Q204
D526-Y
D201
1N4148 U1-B
KA324
R213
5
2.2K
+
7
6
-
D202
1N4148
R212
C203
D203 ZD201 ZD202
470K
223
1N4148 5.6V 7.5V
R211
D200
1MF
1N4004
18V
R312
1W 56
R313
R309
Q301
1W 56
2.2K
A708-Y 1
R307
33K
5
2
Q303
18V
D526-Y
4
R310
2.2K
R308
33K
R311
VR302
Q302
110KF
5K
A708-Y
C305
333
R306
R304
26.1KF
200KF
R305
6.2KF
C304
500V 103
VR301
5K
T201
C206
T1167
6KV 471
1 7
D204
D205
4KV
4KV
5 6
2
C205
C207
2KV 101
6KV 471
4
R216
R218
SBR1/2W 30MJ
MGR1/2W100KF
R215
430
R214
2.2K
R217
C204
SBR1/2W 200MG
473
T301
D304
C307
KAB-006
3KV 471 4KV
6
R315
SBR1/2W 30MJ
7
C306 D303 C308
2KV 680 4KV 3KV 471
R314
2.2KF
THV