Seeking Surf Pi Pro help,connected the battery backwards!

[sentella4d]

Hello;
I have been using my Surf Pi Pro(Surf XX version) extensively at the beach in Puerto Rico and I love it.Yesterday, I accidentally connected the battery backwards and I fried the +5v supply(78L05) and the -5v supply(ICL7660).I replaced both 78L05 and ICL7660,but I have a problem I cannot figure out, I have +5v again but I still cannot get the icl7660 to provide the -5v signal,it will only provide +.26v from pin 5.I went ahead and replaced C13,C14,C15 but that did not work either. I am an electronics beginner,so I really do not know what else to do. Is there any other thing or component that could prevent the 7660 from providing the -5v signal since I already have +5v.

The voltages for 7660 are:
pin1 0v
pin2 0v
pin3 0v
pin4 .26v
pin5 .26v
pin6 1.47v
pin7 5.13v
pin8 4.96v

I am truly lost,Please Help!

[sdesic]

Replace TLC555 too.

[Qiaozhi]

Do you have the ICs in sockets?

By the way, I've removed all the multiple posts regarding this problem. You only need to post your question once.

[sdesic]

Check D4 also - 1N5819

[sentella4d]

Hello;
Dear sdesic;I do not have a 555 right now,i will receive two next Tuesday.I have a question though;how is the 555 timer and D4 related to the -5v from 7660?
Dear Qiaozhi;I cannot removed the IC's,they are soldered.

Thanks for the replies,Sentella4d

[sentella4d]

Dear sdesic;
I replaced D4 but i still do not have -5v in 7660,I still have the same reading of .26v in pin 5.

Thanks,sentella4d

[sdesic]

When you start building you can check connections and voltages by placing 555 and 7660 in sockets - or solder them
555 is giving 7660 sync / osc.

If you have NE555 it should work too - but try it on IC socket so you can change it to TLC later
It can be something else too ... you can't find it without desoldering other ICs

[sentella4d]

Dear sdesic;
I will be receiving some samples of TLC555 not NE555 on Tuesday.But, i remembered that i had one TLC555CDR at home ,but in a 8-soic configuration instead of PDIP.I went ahead and adapted it temporarily by soldering 30 gauge enamel wire to the pins and I was able to mount it temporarily to the board in order to finish diagnosing the detector before my parts arrive.It was hard to solder and make it fit,but I made sure that there are no shorts or bad soldering joints.But I ran into some new problems.When I first turned it on with the coil attached,T2(IRF 9640) would become scorching hot within seconds,i had to disconnect the battery immediately to prevent burning up any more components.I went ahead and tested IRF9640 by following the instructions on this link: http://www.ehow.com/how_7683791_chec...osfet-dmm.html and it passed the test so it seems that it is functioning properly.I guess there is something else wrong with another component or something that is causing the temperature of IRF9640 to go ballistic.

I went ahead and disconnected the coil,and 9640 stopped heating up.I tested to see if i had -5v on 7660 after installing the TLC555 ic and I now have -4.76v in pin 5.I will measure all the voltages for all the other components and I will post the results in a a half hour or so. I really need to fix my detector ASAP,I am really excited to find my first real gold since the beach conditions for detecting in my area are the best I have ever seen(5-6 foot cuts on the sand) since i started the hobby of metal detecting in March of this year.I need to diagnose and fix my detector,before i miss out this opportunity.

Thanks,Sentella4d

[sentella4d]

Hello;
Here are the component voltages after the replacing 555;
7066

1 .02v
2 2.46
3 0v
4 -2.35v
5 -4.73v
6 1.42v
7 4.95v
8 4.95v

TLC555

1 0v
2 6.13v
3 11.35v
4 11.83v
5 7.85v
6 6.13v
7 6.12v
8 11.83v

4093

pin 9,12,14 4.95v
pin 10 -4.65v
pin11 -3.76v
pin 3,4 -4.5v

4066
pin 14 4.95v
pin 6,7,8,9 -4.72v


LM358
pin 4 -4.72v
pin8 4.95v


NE5534
1 3.19v
2 0v
3 .02v
4 -4.73
5 -.065v
6 -.0v,can control with offset
7 4.95v
8 3.06v


IRF9640
G 11.35V
D .04V
S 11.82V


2N3906
E 11.82V
B 11.73V
C -4.14V

[sdesic]

What is your power supply ?
You need to check that coil ... it was working but ... check for shorts in connections to it and resistance /inductance of coil.
Check also R6.

Detector was working ?

[sentella4d]

Hello sdesic;
The detector is not working right now,i have no audio whatsoever.I am currently using a 3 cell lithium polymer battery.The coil is a 8.5" diameter, cat-6 cable twisted pair with 3 turns for a total of 24 turns, with a graphite shield.The coil has a resistance is 1.4 ohms,inductance of around 350 and it was working excellent before the accident.What could currently be causing ta complete lack of audio?.I have a 390ohm damping resistor

Thanks,Sentella4d

[sdesic]

You are lacking -5V ... you need to find that drain ... you really need to try PCB without ICs ... just two of them are enough for testing other components and connections.

Do you have access to oscilloscope ? You can try to follow signal from 555 to speaker.

[sentella4d]

Dear sdesic;
I do not have access to an oscilloscope.I have -4.73 coming from pin 5 of 7660, isn't that enough? I will build an audio utility and test the 555.I will get back to you in a few minutes.
Thanks,Sentella4d.

[sentella4d]

i am still trying to scavange a 1000 ohm resistor,an i use any other value for the utility?

[sdesic]

Dear sdesic;
I do not have access to an oscilloscope.I have -4.73 coming from pin 5 of 7660, isn't that enough? I will build an audio utility and test the 555.I will get back to you in a few minutes.
Thanks,Sentella4d.

-4.73 is OK
what did you do to correct it ?

try to connect piezo speaker to output of ICs ... base of mpsa13 ...

is your R2 trimmer 5k or resistor 3k3 ?
don't know why IRF9640 is overheating... coil is one thing that might be problem ...
did you measure impedance on connector or on coil cable?