Surf PI kit problem on -5v

[chiuino]

Hi there!!
Before writing I checked several posts on the forum but no one has been a real help to know what is wrong with the kit I bought on site silverdog! I state that I do not have an oscilloscope but doing tests with an AM radio I hear the sound produced by the coil. The problem is that I do not have-5V output from 7660-pin5 and as a result even on pin4-5534 and 4066-pin 6,7,8,9 then any kind of sound emitted and no detection of metals. I can not adjust the 0v on pin 6 of the 5534 varying P1.

Many thanks to all those who will want to help me
Andrea

http://imageshack.us/a/img196/5650/t8q5.jpg
http://imageshack.us/a/img89/6850/88h5.jpg

[Tepco]

Business as usual. First remove all chips and verify +5V, 78L05 must be cool. Then insert just 7660 and check for around -4.5V output. If not present, check electrolytic's orientation, bad solder joints, misplaced components around, wrong chip orientation etc, if everything is right, replace 7660, one in 1000 may be bad initially, no way to pretest every individual component in kit, also very fragile chip, will easily blow if overloaded due to some other mistake, (or subjected to overvoltage or wrong polarity). When you get +5 and -5V present, insert other chips one by one, monitoring voltages, at this point ignore any detector response, or lack of it, and post where you got stuck.

(Forum issue whit this post, invalid thread etc ? delete my double post if appear)

[chiuino]

Thank you Tepco for your help and sorry for my bad English!
I have checked and remade all the welds to no avail
The 78L05 output has +4.96 V with and without the cip(7660), but the 7660 does not have to pin5 -4.5V but +0.60V
I recheck all around to 7660 and return to you soon!
Tnx in advance!
Andrea

[chiuino]

It works I have all the right voltages on each pin's on ic's!!!!!
I just did this:
since I could not get this damn-5V or around, I decided to clean perfectly the circuit with an contact-cleaner spray and after I spent rubbing alcohol on both sides well with a toothbrush (obviously without any chip mounted) ET VOILA' everything works!! Now it is only to make a good calibration!
Tnx Silverdog for this kit and tnx Tepco for your help!!! And happy hunting to all

Best Regards
Andrea from Italy!

[Tepco]

Rare, but possible fault. Even a small amount of just partially conducting soldering flux can stop 7660 oscillator operation and disable chip, osc input pin is very sensitive. Good reminder for others to check this and clean the board.

[chiuino]

Hi Tepco!!
I have read around the forum a few changes that could be done to improve the Surf PI. My problem is the interference that are too many and I can not silence them (or almost) without losing much sensitivity! If there is some mod please you or someone else help me!
Many TNX

[chiuino]

I have read this post http://www.geotech1.com/forums/showt...314#post129314
Tepco Article:
My detector is not exactly Surf, but similar, just works whit different timing. I believe this component values will be good for Surf and mod's will work on different boards and SM incarnations.

First, you have to change TX timing, whit these values you will have about 5.2kHz repetition and 18uS pulse. (components referred to "original" White's schematic, check what you have on your PCB version)

Change R2 (3K3), between 555 pin 6&7 to 1.2K (or 1.5K) this will shorten TX to 18 (22us). Change R1 (100K) between 555 pin 8&7 to 10K, to increase frequency.

My question is: can I make these changes to my surf PI 1.2 kit without modifying the sample timing?

Thanks to all
Andrea

[amousetoi]

help please .. I cooked something in my pi .. just a somber tone in no detection outputs
my tensions found in red are those different from those that should be marked in pencil in black
What I'll have 'burned .... someone help me please



[IMG][IMG=2a91]http://img600.imageshack.us/img600/159/2a91.png[/IMG][/IMG]

il 7660
volt foot 1... 1.12

2.... 2.45

3... 0.00

4... -2.42

5... 4.88

6... 2.67

7... 1.17

8... -4.87

[chemelec]

I suggest you remove All the IC's Except the 7660.
Than Test your -5 Volts Again.
If it now reads about -4.5, than you likely have a Bad IC somewhere in the ones you removed.
If it Still reads LOW, than your problem is likely at or around the 7660.

[golfnut]

I made a gas valve with a large accumulator. I burned this one and now I look for reputable transistor. If you have friends too then I will make modern my pen pal. Also with noises I need none as good treasure can always be funny one. Bandwidth time and signals are corrupt demons when trapped in wire strands for your machine. S

[amousetoi]

I have the 7660 volts and -4.9 +4.90
the 78L05 generates 4.90 volts but already on tlc 555 I do not have 5 volts anywhere
I replaced irf 9640 but I think it burned again 'cause much warming
Now, however, 'warms up very little

[chemelec]

The 78L05 should produce +5 Volts, Give or take a Bit. (4.9 Volts is OK)

QUOTE: on tlc 555 I do not have 5 volts anywhere.
OK, But WHY do you think you should?
The Measurements you show on the attached link, Appear OK

[amousetoi]

I'll explain it all over again
Fitting the kit could not detect gold and iron coins but only to 30 cm
reading on the forum I have not found anything that would resolve my case but a lot of interesting news .
I found a nice post explaining something on the frequencies of research and so ' I tried to change the trimmer with a 100k to 200k
with this change and a coil 10 cm wire from 0.90 to 1 mm are able to pick up gold coins and gold I had a reception of 5-10 cm depending on the size of the jewelry.
coins of one euro to about 3-4 cm
At this point I made a new coil of 22 cm with wire always one to do other tests
Since then he has stopped working I cooked something
my knowledge of electronics is limited, and I'm trying to fix it having only a voltmeter.
I already changed 78L05 - 2N3906 - IRF9640 ....... that warmed a lot but still does not work , I think it burned again
I do not know how to find the fault - which component is to actually change
HELP .... please ....... ....... : (

excuse for English and 'with the translator

[amousetoi]

solved

[6666]

So what was the problem so others can learn ?