© Bosch Security Systems, Inc., 2014
12000 Portland Ave S., Burnsville, MN USA
www.rtsintercoms.com
RTS-TB-030
Technical Bulletin
25-June-2014
Page 6 of 7
Channel 1 adjustment procedure:
NOTICE:
The procedures described in the following sections require recording &
comparison of measurements. It may be desirable to keep a table or spreadsheet of
recorded resistance values to track completion.
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1.
Use the op amp locations shown in FIgure 1 to locate U101.
2.
Figure 2 is a magnification of the area around U101. The circle on U101 in Figure 2 represents the
corner corresponding to pin 1.
3.
Figure 3 depicts the package pin out for U101.
4.
Measure and record the resistance between U101 pin 1 and pin 2. This is the resistance of R106 and
should be between 19.00k and 21.00k ohms.
5.
Locate R104 on the bottom assembly print Figure 2. It is just below U101.
6.
Measure and record the resistance of R104.
7.
Subtract the recorded value of R104 from the value of R106. This is the resistance that potentiometer
R105 must be adjusted to match.
8.
Locate R105 on the AIO-16 using Figure 4.
9.
Measure the resistance between pin 1 and pin 3 on R105. Use a screwdriver to adjust R105 to the
resistance calculated in step 7.
10.
Recheck the resistance between U101 pin 1 and pin 2.
11.
Check and record the resistance from U101 pin 3 and any of the AGND posts.
12.
The difference between the resistance recorded in step 10 and step 11 above should be within 40
Ohms. Repeat 9 to 12 until the difference is within working parameters.
3.2
Rework for Channel 2
1.
Measure and record the resistance between U101 pin 6 and pin 7. This is the resistance of R206 and
should be between 19.00k and 21.00k ohms.
2.
Locate R204 on the bottom assembly print Figure 2. It is just below and tot he right of U101.
3.
Measure and record the resistance of R204.
4.
Subtract the recorded value of R204 from the value of R206. This is the resistance that potentiometer
R205 must be adjusted to match.
5.
Locate R205 on the AIO-16 using Figure 4 (it is next to R105).
6.
Measure the resistance between pin 1 and pin 3 on R205. Use a screwdriver to adjust R205 to the
resistance calculated in step 4.
7.
Recheck the resistance between U101 pin 6 and pin 7.
8.
Check and record the resistance from U101 pin 5 and any of the AGND posts.
9.
The difference between the resistance recorded in step 7 and step 8 should be within 40 Ohms.
Repeat 6 to 9 until the difference is within working parameters.