Trouble shooting TP 9 volttage -5v to +5v in Step 8 and Step 9

[jimfrombr]

Hi, I have read each thread and wasn't able to solve my issue. First I the Mini-Pulse ver D was built using the latest instructions from the sticky using a kit from silver dog. The kit was passing all the steps up to 8 when we should see a -5v to +5v swing at TP 9. I am seeing a swing from -3.6 to +4.2. I am using a spiral wound 9.5 inch coil with an inductance of 310uH. I get the low growl at about -1.2. The detector seems to work fine. I checked all the resisters and looked for cold solders. The only thing out of speck is the audio threshold pot supplied in the kit (was 220k instead of 200k, I checked the pot and it was 1-216KR). I can easily detect a gold wedding band in air at 25cm so it working.

Does anybody have any idea how to trouble shoot the voltage at TP9?

PS I don't have a proper oscilloscope I have a 2 channel USB one that does work (sort of, I am a shopping for a proper oscope).

Thanks in advance

[Qiaozhi]

Hi, I have read each thread and wasn't able to solve my issue. First I the Mini-Pulse ver D was built using the latest instructions from the sticky using a kit from silver dog. The kit was passing all the steps up to 8 when we should see a -5v to +5v swing at TP 9. I am seeing a swing from -3.6 to +4.2. I am using a spiral wound 9.5 inch coil with an inductance of 310uH. I get the low growl at about -1.2. The detector seems to work fine. I checked all the resisters and looked for cold solders. The only thing out of speck is the audio threshold pot supplied in the kit (was 220k instead of 200k, I checked the pot and it was 1-216KR). I can easily detect a gold wedding band in air at 25cm so it working.

Does anybody have any idea how to trouble shoot the voltage at TP9?

PS I don't have a proper oscilloscope I have a 2 channel USB one that does work (sort of, I am a shopping for a proper oscope).

Thanks in advance

The detector is working fine. The +/-5V is only a guide. What matters is that you can successfully adjust the audio threshold, not the values at the extremes. If you want to double-check the audio pot, then monitor the voltage at the centre pin of the pot, and note the range of adjustment.

[jimfrombr]

Thanks.