C5.4 T854 Fault Finding M8SL2-00-002-812
© Copyright Tait Electronics Limited August 2004. All rights reserved.
5.4 DC Checks
5.4.1 Power Rails
Refer to the test points and options diagrams in Section 6 for test point locations, and to
the regulator fault finding chart (Section 5.7.2) for fault diagnosis.
Check the 13.8V (TP601) and 9V (TP602) supplies at their test points in the regula-
tor compartment with a DMM.
Check the 5V (TP604) and 20V (TP603) rails at their respective test points in the
regulator compartment.
Check that Tx-Reg. (TP305 in the exciter compartment) comes up to 8.8V when the
exciter is keyed.
Check the +5V digital regulator output (TP607 in the regulator compartment).
Check the 9V supply (IC370 pin 1) with a DMM.
Check for short circuits.
5.4.2 VCO Locking
Key the exciter.
Using a DMM, monitor the VCO control voltage between between L1 and PL14
pin1 on the VCO PCB.
If the synthesiser is locked and the VCO aligned, the voltage at this point should
be between 3 and 16V.
If the VCO is not locked, refer to the synthesiser fault finding chart (Section 5.7.3).
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