LOOKING FOR GOLDSCAN 4 Schematic.

[Jose]

Amarasha
This is what I would do to try to resolve the problem.
Installed U10, I measure the voltage at U4, I follow the line of (-5) measuring with the voltmeter at all points along the way, to see from that point increases the voltage to (-10 volts).
It may be that somewhere GND is interrupted, or the line (-5V).
Could make a bridge on a temporary basis from GND to leg 10 or 12 of U10, to rule out this interumpido GND somewhere.
I wrote what I think, I hope this helps.

Jose

[amarasha]

-5v problem

dear jose
what reason -10v with u10 installed and -5v without u10?
79L05 replaced by another but not different!
Tl064 installed voltage is correct but tl074 not right.
i didn't adjust rv1..rv8 because the legs voltage is 0 V.
can you tell me step by step?

[Jose]

Not what the problem. I would conduct the following steps:
Measure the voltage at the output of U4 (79L05) should be (-5) with U10 installed.
If is (-10), replace U4.

[amarasha]

thanks dear jose
my pcb is smd version. when u10 not installed, leg 4 is -5v but when install u10 on location leg 4 to be -10v!
bridge is correct and tested.

[Jose]

If using the SMD version PCB, I can assume that lack GND bridges.
The bridges are shown as 000.
See drawing.

[amarasha]

hello all
79L05 voltage -5v is correct, but when insert U10, voltage changed to -10v!
anyone help me?

[ABDW9]

tanks jose
when remove u10, the voltage -5v is correct but when i put u10, voltage is -10v.
mean 79L05 not correct?
amaRasha

Welcome to all
I also have this problem
Use 7905 gives out-10v
As for 7905
Use 7805 gives very Dapf effort (0.2) P almost Is this a problem of U1 555??
As for 7905 does not give-5V, but (-10V) What Blazers??
I think this is the problem that makes a key (RRSET) does not work!!
Greetings to you

[amarasha]

tanks jose
when remove u10, the voltage -5v is correct but when i put u10, voltage is -10v.
mean 79L05 not correct?
amaRasha

[Jose]

hello jose
i made gs4 and there are a problem with -5v. when turn on +5 and -12 are correct but -5v is -10v. when i separated tl074 -5v is correct.
what can i do for this problem. i tested and not found any shortcuts.
thanks

Hello Amarasha
Regulator (-5Volts) would have to maintain stable voltage level regardless of current consumption.
I can only make some guesses.
Check the correct installation of the 79L05. Can be inverted. See the catalog of fabicante.
Replace the regulator 79L05, by another 7905 to see if that solves the fault. I and had problems sometimes with 79LXX series.
Verify that this installed and in good condition 22 mf capacitor this output to the 79L05.
Hope this helps. Jose

[amarasha]

-5v problem

hello jose
i made gs4 and there are a problem with -5v. when turn on +5 and -12 are correct but -5v is -10v. when i separated tl074 -5v is correct.
what can i do for this problem. i tested and not found any shortcuts.
thanks

[ABDW9]

Davor and Porkluvr Thanks for clarifying these issues.
ABDW9, if you have oscilloscope check the noise level at the output of 5534, with the coil disconnected. If noise is high for some reason, the detector becomes unstable and impossible to tune.
Best Regards
Jose

Hello again
Well I will do
And tell you participate next
Thank you for your attention
Greetings

[alonejax]

hi to all

any body make gold scan 4?
what is max sence meter for gold in dept? is a good detector?
thanks

[Jose]

Davor and Porkluvr Thanks for clarifying these issues.
ABDW9, if you have oscilloscope check the noise level at the output of 5534, with the coil disconnected. If noise is high for some reason, the detector becomes unstable and impossible to tune.
Best Regards
Jose

[Davor]

BF245 is by definition a symmetrical one. It is easier to find it here than the J parts.

When mentioning the diode test, next time check the barrier voltage ... it is lower than the usual silicon diodes, as they are not doped as much. May come handy sometimes.

[porkluvr]

KT 315
In post # 4 you could see in this way the location of the drain and source.
Anyway, Geotech forum members, saying that small signal configurations as in this case, drain or source can be connected either up or down.
Regards

Some manufacturers will tell you if a particular JFET has interchangeable S & D. Other manufacturers will have the "identical" part number but their data sheet will say nothing about S-D interchangeability.

For instance, the Philips (NXP) and Fairchild data sheets, state "S & D are interchangeable" for the J111~J113.
Vishay's J111~J113 spec sheet, however, makes no mention.

Another way of stating S-D interchangeability is "symmetrical".
Not all JFETS are symmetrical. Do not assume that all JFETS are symmetrical just because some of them are.

2N4393 looks like it may be a good sub for J113 and Fairchild's 2N4393 datasheet does state S & D being interchangeable.

EDIT: So, what this all means is that if you are doing a PCB layout and run into a problem with a J113, you can sometimes side-step the issue by making a pin-swap.

You can get an ohm-meter and measure from G-D and G-S and you should get identical readings. Same with a diode test.