TP2 at 7V

[Tibuck19]

Hi guru's , quick question, I built the mmp D version a while ago and been using it with a fast coil, Now I wanted to make a complainer coil for It, So I pulled the board from its case and set it up on the bench to better adjust it when the coil is done, mean while, I was poking around with Scope and multimeter , I notice im Getting +7 volts on Tp2 and other spots that I should be getting 5V, has anyone had this issue or perhaps the 78l05 is going bad?? Any clues gentlemen.

[Qiaozhi]

Hi guru's , quick question, I built the mmp D version a while ago and been using it with a fast coil, Now I wanted to make a complainer coil for It, So I pulled the board from its case and set it up on the bench to better adjust it when the coil is done, mean while, I was poking around with Scope and multimeter , I notice im Getting +7 volts on Tp2 and other spots that I should be getting 5V, has anyone had this issue or perhaps the 78l05 is going bad?? Any clues gentlemen.

Are you sure you're measuring with reference to TP10 (0V)?

Also, I guess you meant to say "coplanar coil".

[homefire]

Everything else checked out , a bit of resistance on the control leg of the 78L05 could cause the voltage to go up. Check Solder joints.

[Tibuck19]

Are you sure you're measuring with reference to TP10 (0V)?

Also, I guess you meant to say "coplanar coil".

George to the rescue once again d'oh! how did I missed that! yes indeed when I reference TP2 to using TP10 I do indeed get the 5V loll Thanks. Coplanar! Complainer! lol lets pretend they are both one and the same hahah I Got my handbook In the mail today, I ll be reading tonight ! Nice quality guys i'm glad I finally decided to get it.

[Tibuck19]

Everything else checked out , a bit of resistance on the control leg of the 78L05 could cause the voltage to go up. Check Solder joints.

Thank you for your help Homefire, Turns out its fine, I was just not taking the correct reference points But thanks nonetheless.

[Tibuck19]

Are you sure you're measuring with reference to TP10 (0V)?

Also, I guess you meant to say "coplanar coil".

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?

[green]

Voltage on all three pins of the 78L05?

[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.

[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]

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]

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]

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

[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]

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.

[WM6]

Possibly to high damping R.