GROSS TROUBLESHOOTING PRELIMINARY INSTRUCTIONS.

TM 11-5820-401-34-3/0967-LP-432-3060

GENERAL. (CONT)

3-11.

GROSS FAILURE TROUBLESHOOTING

Gross failure troubleshooting is generated by failure of the VOLUME control test, the first of the

performance tests in section I of this chapter. Failure of the VOLUME control test indicates that no

audio at all is available at the receiver's loudspeaker jack. This implies a total failure of some module

or component resulting in complete loss of signal. Therefore, the gross troubleshooting charts are

designed to help you locate the failed module or component, with the assumption that the failed part

does not operate at all.

This assumption differs from the approach taken in performance degradation troubleshooting, which

assumes that a module or component may be responsible for slight defect symptoms because the part

may be only partially operational.

PERFORMANCE DEGRADATION TROUBLESHOOTING

When the receiver produces audio output, but the signal fails to meet certain standards, the receiver's

performance is considered degraded. Degraded performance can result in weak audio, limited

reception range, distortion, and many other problems.

The troubleshooting charts are designed to locate the cause of the performance degradation by using

procedures more complex than those utilized for gross troubleshooting. Added complexity is due to the

fact that the troubleshooting tests must evaluate the quality of the signals at various test points, instead

of merely confirming the presence of signals as is usualIy the case in gross troubleshooting.

OVERALL TROUBLESHOOTING APPROACH

Both kinds of troubleshooting charts contained in this section are intended for use based on the

following assumptions in connection with the R-442/VRC.

1, Only one malfunction exists which is causing the defect symptom.

2. The troubleshooting charts do not isolate every possible defect.

3. Failure to locate a defect using the charts suggests a wiring-related problem which can be

isolated using the schematics located in the back of this manual.

4. Troubleshooting procedures for germanium and silicon versions of the R-442/VRC are the

same.

3-12.

GROSS TROUBLESHOOTING PRELIMINARY INSTRUCTIONS.

The gross troubleshooting charts in this section are based on the assumption that the receiver fails the

VOLUME control test at any frequency setting of the MC-TUNE-KC control. However, certain defects

in the crystal reference system can result in loss of audio at some frequencies while the receiver can

function normally at other frequency settings.

3-34