Help Identifying Components, and tinkering with circuit design

[THATguy]

This is from metal detector pointer:  Vibra Probe 580.
The second picture is of the tiny coil, 15mm diametre.

Firstly I want to change the vibrator to a smaller one, pretty easy, I might use a resistor if necessary.

I do want to replace the coil for a ferrite core coil. However that might be a job that requires tuning with a scilloscope.

To turn the coil on it is held upright for 3 seconds. However it auto turns off 1 minute after last detection, a very annoying feature. I really want to be able to increase this timer to 5 minutes. I suppose that would require reprogramming a chip, perhaps only reorganising the circuit board.
I'll map it if anyone wants (I've partially started).

I have a multi meter and LCR meter.
How do I test the N components, or can I identify them by the labels?
Are they Varator diodes?

Can I measure all the tiniest R & C components while off?
Guess I'd use the LCR for the C (capacitors?).

While trying to ID some of the components I came across these pages which I found to be very helpful:
Testing components
http://www.talkingelectronics.com/projects/Testing%20Electronic%20Components/TestingComponents.html
PCB markings
http://electronics.stackexchange.com/questions/25308/what-do-the-pcb-markings-mean

GLOSSARY FOR THE ATTACHED IMAGE.
B - they have 4 pins each
N - are these the same thing, how would I test them/identify them. Small one reads 44 & D3 written on the PCB (some read IP with Q3 written next to them) Varactor Diodes?
T - vibrator
H - 16.0M, U3 written on circuit board, mlc?
Y - PIC16F5 -/ISO (Flash-Based, 8-Bit CMOS
Microcontroller Series) Data sheet was found.
U - [PEUAC] MM74HC 132M Not sure which data sheet this is?
I - EA33  LM 324M (Low Power Quad Operational Amplifier) There are data sheets, but I can't find one ending in only 324M
O - S 1346 P   BSP170
A - jumper to connect the coil

[danadak]

Weather of not you can test components in circuit depends on how they
were used in the circuit. You need a schematic to see if the associated
components are affected by the stimulus you use for measurement.

One way, for thru hole components, is lift one leg and test, that way
you can measure R, L, C and associates ESR.


Regards, Dana.

[Zero999]

Don't worry about the M-suffix, just look up the datasheets for the LM324 and 74HC132.

[Nullarbor]

Thanks for the good PCB and Coil pictures. Was always wondering what the Vibraprobe looks like inside.

How far did you go with experimenting with this, new coil perhaps with ferrite? I find the 1 minute switch-off annoying too.
Don't think you can change that without re-programming.

Anyway,
"B" are most likely tilt-switches
"H" is a 16MHz resonator for the PIC
"O" is the mosfet that pulses the coil, controlled by the PIC

Not sure about "N":

The 3-pin part might be a transistor, but if D1 designation is for that then diode, maybe back to back one.
The 4-pin part might be an opto-coupler.

Cheers.