help with tesoro silver umax

[giuhalftrack]

hi everyone !!

i'm here today for ask help from you.

short story.
my tesoro silver uMax is "broken" if I power the unit with battery i only measure 2.4 V across the battery (fully charged) and no sound came out (detector dead), the battery is drained fast.

if i power the unit with a bench power supply the unit works as normal...

it is obvious to me (i hope) that there is some form of "short" somewhere and the bench power supply has enough power to feed the short and the circuit too, but the normal battery can't.

what I'm asking:
have you ever experience a failure like this ?
in which part of the circuit i should look to find the problem ?

additional information:
the repair process....
i have desoldered audio transistor thinking of a failure of the audio stage but they are good, so i have tested the micro controller (pic16F73) and i have noticed that no "audio signal" is coming out from RC0 RC1 (pin 11 - 12).
if i connect the bench power supply a beautiful 390 KHz square wave came out of those pins..
so i decide to reassemble all to discover that with bench power supply the unit is working as new...

maybe i must transform my detector in a way to be connected to main even in field ???

thank you

[Andi68]

Check switch, potentiometer, check electrolytic capacitors

[dbanner]

You neglected to measure the current consumption when connected to bench supply. This is sure way to know if something is wrong with the device. Inordinate high current consumption points to a leaking component but not a short, which would have probably led to magic smoke.
Maybe just the battery needs replacing.
You measure output of pic, but forgot basic first steps?
Also, you must be suspicious of the PIC, check out how warm she gets. If she running hot to the touch.

[kt315]

can you give pics?

[giuhalftrack]

Check switch, potentiometer, check electrolytic capacitors

ah ok !! i'll do that

You neglected to measure the current consumption when connected to bench supply. ...
......You measure output of pic, but forgot basic first steps?....

i'll check the current consumption but i don't know the normale current consumption..

for the basic steps ... yes sometime i do this stupid error ...

[giuhalftrack]

can you give pics?

i have a video of the disassembly process, i post this and pics as soon as possible...
in the repair process i have collected some data about the schematic and pcb of the silver so i'll post here to help others in future.

[kt315]

Check switch, potentiometer, check electrolytic capacitors

he must do pics of boards with wires (to know how and where to solder them back).
then desolder all wires from board and again do pics.
check switch - by any tester, on close-on state. do not desolder wires from switch.
this is plastic and without needed experience you will melt out the plastic.
check pots - by any tester, in kOhm range.
check electrolitics - by chinese transistor tester, in ESR range.

[kt315]

[giuhalftrack]

ok i've check capacitor (on circuit) and they are not shorted..

more clues from current consumption.

i made this test:
with the bench power supply set on constant current 20mA detector doesn't turn on..
if i increase the current i reach a 50 mA peak and detector start working, the current consumption is now 13 mA (silent) and 40 - 50 mA (with sound from the speaker)

i'm thinking about some "current regulator" or some "turn on circuit" have fail in the board... maybe a charge pump ? any idea ?

p.s i think all the broken wires that i found are broken during disassembly so they are not cause of the problem.

[dbanner]

Why fully charged battery not work but regulated bench supply make device work flawlessly?

[kt315]

BTW what type of battery you use?

[giuhalftrack]

he must do pics of boards with wires (to know how and where to solder them back).
then desolder all wires from board and again do pics.
check switch - by any tester, on close-on state. do not desolder wires from switch.
this is plastic and without needed experience you will melt out the plastic.
check pots - by any tester, in kOhm range.
check electrolitics - by chinese transistor tester, in ESR range.

ohh i must prepare myself and my mind to desolder all the wires
some of the test you said i have already made but for sure i redo when i desolder all the wires...

the pics you post are different from my unit (maybe an old silver all analog ?) the last picture is like mine. thank you.
please check my other post with "current consumption clues"

thank you again

[giuhalftrack]

Why fully charged battery not work but regulated bench supply make device work flawlessly?

i'm using a NIMH battery and i have tested with power supply at 8.7V ... the path from battery to PCB is tested and is good

[dbanner]

Nothing is wrong with the detector. The current drain you noted above is normal. Try different battery. Like typical 9V alkaline Duracell.
If you like tinkering, then disassemble entire unit and reverse engineer with high res pics of top and bottom PCB.
You will make KT315 go orgasmatronic.

[kt315]

uff it is just 9V chinese one...

You will make KT315 go orgasmatronic

BTW i have HR pics, but if you had grasp i do not put them on first click LOL.