Shure T1 Body-Pack Transmitters
19
Bench Checks
25C1016 (CC)
Excessive Current Drain
n Try readjusting C215 for lower current drain while maintaining
output power to specification. If the current drain is still exces-
sive, check for the following:
S short
S wrong resistor value
S shorted capacitor
n As a last resort, try changing Q204.
Deviation
n If R217 cannot be adjusted to obtain a "15 kHz deviation, try to
isolate the problem to the audio or
RF section by doing the fol-
lowing:
S If
TP3 does not measure –2.2 dBV (775 mV), refer to the
“Audio” subsection, above.
S If TP3 has the right level, check R217, C220, C227, R208,
R216, D201, R209, L209, and C214. Also make sure that
the cathode of D201 is being supplied with a 5 Vdc bias from
the 5 V Line through R216 and R208. The value of C214 is
critical to the deviation sensitivity.
n As a last resort, try replacing D201 and Y201.
n Make sure the carrier is good: you need that to get any devi-
ation.
Distortion
n Make sure the analyzer’s 400 Hz high-pass and 30 kHz low-
pass filters are ”In.”
n Pin 9 of U101 should read about 1.8 Vdc.
n As you turn R130, the dc level on its wiper should change from
about 1.5 V to 3.5 V. If it does not, check R129, C125, R130,
R141, R140, R126, and the parts tied to pin 9 of U101.
n Check the audio level.
n Lastly, replace D201 and Y201.
