TP2 at 7V

[green]

Maybe this could help solve the problem, R21, 10K is reading as 8K and r22 56K is reading as 22K. And they are the correct resistors.

Why would R21 and R22 effect +5v supply? Maybe a stupid question, what voltage would you read if the 78L05 was connected reversed?

[Tibuck19]

Maybe this could help solve the problem, R21, 10K is reading as 8K and r22 56K is reading as 22K. And they are the correct resistors.

[Mdtoday]

I replaced the 78L05 and went around the board re-soldering and cleaning with IPA just to make sure, the single seems to be coming for the power supply I think ?

Sounds like you have a broken common connection to the 5v regulator.

Brian

[Tibuck19]

Have you looked at the +and-5v with a scope? Don't see how can get 7v unless 78L05 is bad or leakage across input to output pins of 78L05.

I replaced the 78L05 and went around the board re-soldering and cleaning with IPA just to make sure, the single seems to be coming for the power supply I think ?

[green]

Have you looked at the +and-5v with a scope? Don't see how can get 7v unless 78L05 is bad or leakage across input to output pins of 78L05.

[Tibuck19]

Possibly to high damping R.

as it stand I took off the R1 and its on a variable resistor. but if I lower the resistor value I lose all sensitivity.

[WM6]

Possibly to high damping R.

[Tibuck19]

would explain the poor performance, when I had put it all together a while ago I could swear I was getting more depth, hens is why I want to make a concentric coil. I will try to figure out the frequency.

[homefire]

Emmm Looks like some other signal is riding on your intended signal. Not just noise. Try to figure out what frequency it is. Stretch it out and see if you can figure out the freq.

[Tibuck19]

If you've fitted a 78L08, then that's the problem. It should be a 78L05.

It was a typo , it is the 78L05 I replaced

[Qiaozhi]

Yes Pin 4 Of u8 is at -5V , I replaced the 78L08 and it is also the same at 7 V,

If you've fitted a 78L08, then that's the problem. It should be a 78L05.

[Tibuck19]

What about the -5V supply? Does that measure ok?

Yes Pin 4 Of u8 is at -5V , I replaced the 78L08 and it is also the same at 7 V, EDIT: Also the tail end of Tp4 on the scope is very dirty meaning the line has lots of noise in it passed the dip , I ll poste a photo in a few mins

[Qiaozhi]

George I thought I was getting 5V from tp2 with tp10 but I looked again and I am still getting 7V, I flipped the board and went around every solder joint but still same 7V it was working fine before but 2 extra Volts is still two too many, Any idea's?

What about the -5V supply? Does that measure ok?

[Tibuck19]

Voltage on all three pins of the 78L05?

12V 0V 7V , ill have a look to see if I don't have a spare one and replace it.

[green]

Voltage on all three pins of the 78L05?