Ivconic built this machine and it is working fine for him. There are 2 parts to the detector: The charging circuit, and the sensing circuit. You can test the charging circuit with a digital volt meter. Connect between the dish and the battery ground. you should have at least 12 volts. if not there is a problem in the charging circuit that needs to be corrected.
The sensing circuit is seperate from the charging circuit. There should be no connection between the two. Test for continuity between the ground of charging circuit and the ground of the sensor circuit. if it is less than 1 meg ohm then I would look for where the leak is. Also test between the antenna and dish. This should also be more than 1 meg ohm. If you find these two circuits are connected, then there is a chance of damage to the TL op amps.
If these 2 tests test ok, then the remaining sensing circuit is a simple differential amplifier and power amp stages to run a speaker and meter. You can test each stage at a time to locate the problem. be careful with the TLC271 and TLC272. These are FET devices and can be easily damaged if you touch the leads when you have a static charge on your hands. Use a grounding strap on your wrist.
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