aor: AR7030 with a strange malfunction

My AR7030 surprised me with a strange malfunction: from time to time, a strange peeping noise, the panel goes blank, the receiver stops working …

Checking the reason for the apparent short-circuit leads to the ‚+10db‘ position of the RF-IF button and the reason seems obvious, Q16.

De-soldering the transistor solves the short-circuit problem, but following this operation the receiver delivers static only on any AM signal but normal reception on the sidebands, FM and CW.

Measuring the usual suspects gets you nowhere – everything seems to be ok until you reach the 2nd mixer, but the IF amp has no input signal. The apparent culprits could well be the 4053 switching circuits and/or Q83, a 4094 controling the swichting ICs.

When faced with an SMD cemetary one hesitates to de-solder more ICs than absolutely necessary … which leads to a prolonged phase of thinking things over.

In the end it was, as it most often is the case, the simplest thing. Probably caused by the short, the memory ‚forgot‘ its filter bank config and a reset plus a new filter calibration made it remember again it had an AM filter.

As I never used the +10db RF gain position I just left Q16 out and we’re happily living together again, my 7030 and I.

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