Hammerhead Rev. D build schematic info

looking good mate keep at it

i would love to compare circuits if you can share some time

Hi Ron,
I;m afraid I don't have a great deal only what I have downloaded from Silverdog's shop in UK which you are welcome to. I also have Carl Morelands publication " Inside the Metal detector " which has a few P.I. Circuits which are a bit advanced for me to grasp at the moment.
Cheers
Dave.m

Hi Dave
Could you find out which is dropping the +5V(IC6 Pin 7) off.First replace IC6 and see if it drops.If it doesn't then remove it and reconnect R37 and C11 and see if it drops.Could you also check the value of R37 to make sure it is 10K and C11 to make sure its not short circuit.
N.B Lifting the leg off R37 will do the same as removing C11 as they are in series.

This may or may not have anything to do with why your board is not working correctly but you are using way too much solder on your connections plus the temp of the iron may be a bit low going by the appearance of the blobs of solder.
You could easily have some dry joints there or possibly have overheated a component  due to the iron being on the joins for too long. or possibly solder can bridge across connector pads or CB tracks

Side view of a good solder joint on a PCB

Hi Steve,
I have carried out the procedure that you suggested to find that with IC6 refitted the voltages remained almost the same as without.I the refitted C11 and R37 removed IC6 and the voltage dropped so I then checked R37 and it measured 9.97K on myDMM. It appears as though C11 is blown.
Cheers
Dave.m

Hi Adrian,
Thanks for the advice. I did realise that my soldering was pretty ordinary and I purchased another iron rated at 30w and reduced the solder diameter back to 1mm, hopefully with more experience my soldering will improve, point taken and I do appreciate your input.
Cheers
Dave.m

Dave if you not getting things to go feel free to send me the board and i will go over it for you no charge
cheers Ron

No probs Dave.
Sometimes an easy fix is just a solder joint away. So check the easy stuff first like solder connections and cables and that all components and IC sockets are in their correct positions and the correct way around.

Dave.m wrote:Hi Steve,
I have carried out the procedure that you suggested to find that with IC6 refitted the voltages remained almost the same as without.I the refitted C11 and R37 removed IC6 and the voltage dropped so I then checked R37 and it measured 9.97K on myDMM. It appears as though C11 is blown.
Cheers
Dave.m

When you say C11 is blown do you mean shorted or open cct? what is the value of R37 (Colour code) ?
Pretty unusual for those caps to be stuffed unless you cooked it.

If it is shorted your MMtr will show it but if it is good or open you will not get much of an indication with an ordinary Multimeter.
Use a high ohms range and look for a very slight kick of the meter pointer when the probes ar connected accross the cap. (very rough check)

If you toasted R37 then the resistance will go very high

Hi Steve,
I went back over R37 and found it was of the incorrect value (Brown ,Black, Black ,Orange and Brown). C11 I thought was open as I could not get any indication what so ever. I went ahead and replaced both with new items  and everything worked well.
IC5 pin 1=-4.92v
IC11 pin 8 = -4.92v
IC12 pin 8 = -4.92v
IC5 @ TP1 = -1.3v
IC6 pin 7 = + 4.92v
IC6 pin 4 = - 4.87v
Thanks for your help.
Cheers
Dave.m

Good to hear Dave,glad you've got to the bottom of it.Something that you may need is some shielding inside the control box,see how you go when the project is up and running.

Dave.m wrote:Hi Steve,
I have carried out the procedure that you suggested to find that with IC6 refitted the voltages remained almost the same as without.I the refitted C11 and R37 removed IC6 and the voltage dropped so I then checked R37 and it measured 9.97K on myDMM. It appears as though C11 is blown.
Cheers
Dave.m

Sounds like R37 was the problem.
Very low value caps will often not cause any deflection of a normal analogue multimeter and a digital meter can be insensitive to the cap charging current.
Colour code Brown Black Black is 10 ohms.
You measured 9.97k ohms. You either mis read the meter or the range cal is wrong and 9.97 ohm would be correct for that resistor code and tolerance.
That was why I asked about the colour code. 10 ohm would have been too low  in that position.
Just curious. What was the correct value?

Hi Adrian,
R37 was 10K resistor.
Cheers
Dave.m

What I ment was that the resistor fitted was 10 ohms when it should have been 10k.

Hi Adrian ,
The R37 resistor that I removed was 10 ohms.
Cheers
Dave.m

I have just struck another problem regarding the build of this PCB as  I 'm not getting the required voltages at TP4. I have done some voltage checks across the board which are as follows:
IC3 CTR Pin = -12.6
     LH Pin  = -5.03
     RH Pin = .0
IC2 CTR Pin = 0
     LH Pin = +11.02
     RH Pin = +5.06
IC4 CTR Pin = -12.61
     LH Pin = -4.99
     RH Pin = 0
IC5 Pin 1 = -4.99
IC11 Pin8=-4.99
IC12 Pin 8 =-4.99
TP1 = - .75
IC6 Pin7 = +4.98
     Pin4 = -4.98
TP4/Pin 6 =+4.36
R18 at central adjustment on lower contacts CTR Pin = -3.20
                                                                  LH Pin = -3.20
                                                                 RH Pin = -4.94
TP3 = -.69
IC7 Pin 14 = +5.06
     Pin 7   = - 5.03
     Pin 2 = +4.32
     Pin 3 = + 4.32
IC8 Pin 8 = +5.06
     Pin 4 = -5.03
R18 is not indicating any changes of voltage at TP3 and TP4 is also not indicating any variations can anyone give me a clue to what the problem could be. Also I have replaced IC's 5&6 with new items also R19 with a 100k resistor rather than the 1m resistor also called for in the parts list and resoldered all of the joints that were looking a bit iffy. I have rechecked the above voltages and amended the figures if there was any differences. Any help would be greatly appreciated.
Cheers
Dave.m

do you have a current picture of the board both side please ?

[quote="Dave.m"]I have just struck another problem regarding the build of this PCB as  I 'm not getting the required voltages at TP4. I have done some voltage checks across the board which are as follows:
IC3 CTR Pin = -12.6
     LH Pin  = -5.03
     RH Pin = .0
looks ok to me

IC2 CTR Pin = 0
     LH Pin = +11.02
     RH Pin = +5.06
looks ok to me

IC4 CTR Pin = -12.61
     LH Pin = -4.99
     RH Pin = 0
looks ok to me


IC5 Pin 1 = -4.99 correct

IC11 Pin8=-4.99  correct
IC12 Pin 8 =-4.99 correct
TP1 = - .75   possibly correct as it is a pulse not dc
IC6 Pin7 = +4.98
     Pin4 = -4.98 correct
TP4/Pin 6 =+4.36 dont know it should be looked at with cro
R18 at central adjustment on lower contacts CTR Pin = -3.20 ok
                                                                  LH Pin = -3.20  looks like that is ok too
                                                                 RH Pin = -4.94 ok
TP3 = -.69 not relevant yet
IC7 Pin 14 = +5.06   ic7 look ok with no signal
     Pin 7   = - 5.03
     Pin 2 = +4.32
     Pin 3 = + 4.32
IC8 Pin 8 = +5.06  ic 8 correct
     Pin 4 = -5.03

Note:  the voltages you are checking are just the supply to the various ic's

R18 is not indicating any changes of voltage at TP3 and TP4 is also not indicating any variations can anyone give me a clue to what the problem could be. Also I have replaced IC's 5&6 with new items also R19 with a 100k resistor rather than the 1m resistor also called for in the parts list and resoldered all of the joints that were looking a bit iffy. I have rechecked the above voltages and amended the figures if there was any differences. Any help would be greatly appreciated.
Cheers
Dave.m


nothing wrong at R18 imo

i will compare circuit with your parts placment a bit later
but to me so far everything looks fine
cheers Ronk

put the rest of the parts in Dave