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#21
August 25th 09, 11:52 AM
posted to rec.radio.amateur.boatanchors
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AR88 -- help!
Richard Knoppow ha scritto:
"MoiInAust" wrote in message ... Thanks again Piero. Interleaved as before "Piero Soldi" wrote in message ... OK, make some measures. With a VTVM or other *high* impedance voltmeter, make a reading at juncton between R43 and C97 ( 4uF ) and chassis ground. Must be approximately *minus* 3-4 volt. That's the foot of the AVC chain and surely 3-4 Volts is *much* too low. I get 27-30, which would be expected with a total current of 110 mA and a total AVC chain of 275 Ohms. Again, make a measure at junction between pot R46 pin 3 with R55 and chassis. Must be approximately *minus* 0,3-0,4 volt. There is no pot R46. Do you mean RV3. Which do you mean by 'pin 3' Cheers Alan The designations are different on the US and UK versions of the schematic. RV-3 and R-46 are the same, i.e., the RF gain pot. The voltage table specifies measuring to the pot but fails to say which contact. Since the pot is variable (doh) that makes a difference. There is a US version of the schematic at BAMA which will show the differences in component lables. I still can't see how the AVC bus could become positive unless there is something shorting it to the B+ (HT) or else you are measuring to the wrong reference. -- Richard Knoppow Los Angeles WB6KBL Hello Alan, Richard and Colin. Alan, yes, i've done a tenfold error ! Take in good advice what Richard say, about the AVC bus, he's absolutely correct, *if you are shure of wiring redone*. The Richard's subsequent reply is *perfect* to pin down the error(s) or defective component(s), and also the Colin's reply is of great help. I can't add anything to those replies. Good debugging, cheers, Piero. |
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