Hello all,

I took a chance on buying a Scout 40 (a frequency counter/recorder
made by Optoelectronics) used on Ebay, knowing full well that it was
inoperative due to the original owner using a reverse polarity power
supply by accident. My thinking was that it would be something simple
like a blown diode or internal fuse. It was NOT a fuse or diode, but I
did spot a badly heat blistered transistor like component. One oddity
about this whole affair is that while I was experimenting upon the
dead frequency finder, it actually powered up and began to run
normally, so I know that the majority of the electronics must be fine,
but then it failed and I have not been able to raise it from the dead
since let alone find out what I did to make it run to begin with.

Anyways, it's early morning and I am babbling. What I really need is
help identifying and replacing this part:

http://www.projectradiantlight.com/S...ansistor_1.jpg

http://www.projectradiantlight.com/S...ansistor_2.jpg

The part is just below the leftmost switch between it and a large
mounting hole in the main board. It appears to have the same case
style as a common surface mount transistor with the exception that it
has five leads, which I am totally not used to seeing. The part number
is "U13", and is marked L01B. There is a central heat blister
indicative of catastrophic internal damage, and surely must be dead as
a hammer, and it is indeed in the area of the main PCB that is
responsible for power input and charging control.

Anyone who can help me a bit with this, please do. I will be eternally
grateful if I can ressurect this $360 (when bought new) item!

Thanks MUCH for any help!

Rick

"The usual approach of science of constructing a mathematical
model cannot answer the questions of why there should be a
universe for the model to describe. Why does the universe go
to all the bother of existing?"

- Stephen Hawking

---------------------------------------
Amateur Astronomy Page:
http://www.angelfire.com/alt2/nightrunner/skyview.html

Our Webcam:
http://web.infoave.net/~missy1/cam/webcam.html

"NightRunner" wrote in message
...
Hello all,

I took a chance on buying a Scout 40 (a frequency counter/recorder
made by Optoelectronics) used on Ebay, knowing full well that it was
inoperative due to the original owner using a reverse polarity power
supply by accident. My thinking was that it would be something simple
like a blown diode or internal fuse. It was NOT a fuse or diode, but I
did spot a badly heat blistered transistor like component. One oddity
about this whole affair is that while I was experimenting upon the
dead frequency finder, it actually powered up and began to run
normally, so I know that the majority of the electronics must be fine,
but then it failed and I have not been able to raise it from the dead
since let alone find out what I did to make it run to begin with.

Anyways, it's early morning and I am babbling. What I really need is
help identifying and replacing this part:

http://www.projectradiantlight.com/S...ansistor_1.jpg

http://www.projectradiantlight.com/S...ansistor_2.jpg

The part is just below the leftmost switch between it and a large
mounting hole in the main board. It appears to have the same case
style as a common surface mount transistor with the exception that it
has five leads, which I am totally not used to seeing. The part number
is "U13", and is marked L01B. There is a central heat blister
indicative of catastrophic internal damage, and surely must be dead as
a hammer, and it is indeed in the area of the main PCB that is
responsible for power input and charging control.

Anyone who can help me a bit with this, please do. I will be eternally
grateful if I can ressurect this $360 (when bought new) item!

Thanks MUCH for any help!

Rick

"The usual approach of science of constructing a mathematical
model cannot answer the questions of why there should be a
universe for the model to describe. Why does the universe go
to all the bother of existing?"

- Stephen Hawking


U is a common designation for integrated circuit. i would go direct to the
company first.
http://www.optoelectronics.com/

they might send you a schematic as a courtesy.

On Fri, 07 Apr 2006 06:15:23 -0400, NightRunner
put finger to keyboard and composed:

What I really need is
help identifying and replacing this part:

http://www.projectradiantlight.com/S...ansistor_1.jpg

http://www.projectradiantlight.com/S...ansistor_2.jpg

The part number is "U13", and is marked L01B.

It's a LP2980IM5-5.0 Micropower 50 mA Ultra Low-Dropout Regulator by
National Semiconductor.

http://www.national.com/appinfo/powe...68,484,00.html
http://www.national.com/pf/LP/LP2980.html

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Hey man that was great of you, thanks!!! I'm checking out the
specifications PDF file now... If I can route 5V power around this
thing, then I can at least test the rest of the device and ascertain
whether there are any further damages. I'll keep y'all posted on how
it goes with this!

Thanks again!

Rick

On Sat, 08 Apr 2006 06:50:12 +1000, Franc Zabkar
was reportedly seen on the White House
lawn holding a large picket sign and screeching the following:

On Fri, 07 Apr 2006 06:15:23 -0400, NightRunner
put finger to keyboard and composed:

What I really need is
help identifying and replacing this part:

http://www.projectradiantlight.com/S...ansistor_1.jpg

http://www.projectradiantlight.com/S...ansistor_2.jpg

The part number is "U13", and is marked L01B.

It's a LP2980IM5-5.0 Micropower 50 mA Ultra Low-Dropout Regulator by
National Semiconductor.

http://www.national.com/appinfo/powe...68,484,00.html
http://www.national.com/pf/LP/LP2980.html

- Franc Zabkar


"The usual approach of science of constructing a mathematical
model cannot answer the questions of why there should be a
universe for the model to describe. Why does the universe go
to all the bother of existing?"

- Stephen Hawking

---------------------------------------
Amateur Astronomy Page:
http://www.angelfire.com/alt2/nightrunner/skyview.html

Our Webcam:
http://web.infoave.net/~missy1/cam/webcam.html

Interesting news with this little bugger... I have it almost repaired!
Thanks to Franc's post, I got out two irons and very gently removed
the regulator chip, and found as I should have forseen that this had
zero to do with the unit being dead. The regulator's only job is to
lower the 12v adapter voltage to 5v so it can run the unit without
smoking it yet again. The real damage remained at that point unseen,
and might have plagued me MUCH longer except that a tiny glint of
copper caught my eye between the power and filter switches, and on
closer inspection I discovered that it was another heat stressed part
of the board. I very gently removed a large diode that this heat
stressed trace ran beneath, and discovered much to my joy that it was
completely burned in half. I then took a small piece of wire and
completed the circuit with external batteries powering the unit, and
presto, it powered right up, and ummm... stayed powered even after I
removed the jumper wire. It must be a flipflop type of power on/power
off toggle. Anyways, I carefully took the whole delicate in hand and
got out one of my FRS walkie talkies, and it tests out perfectly. I
still have some major repairwork to do, but I can't say how pleased I
am... I've wanted one of these buggers like forever and just could
never justify the expense. Now I have a fully functional $360
frequency recorder for a mere $60! Well, ok, a bit more than that
after that IC, but still!

THANKS both of you for helping me!! Now all I need is a new regulator
IC and some VERY delicate work to repair that melted trace, and I'll
be all set! :-D

Rick

"The usual approach of science of constructing a mathematical
model cannot answer the questions of why there should be a
universe for the model to describe. Why does the universe go
to all the bother of existing?"

- Stephen Hawking

---------------------------------------
Amateur Astronomy Page:
http://www.angelfire.com/alt2/nightrunner/skyview.html

Our Webcam:
http://web.infoave.net/~missy1/cam/webcam.html

On Fri, 07 Apr 2006 20:05:35 -0400, NightRunner
put finger to keyboard and composed:

Interesting news with this little bugger... I have it almost repaired!
Thanks to Franc's post, I got out two irons and very gently removed
the regulator chip, and found as I should have forseen that this had
zero to do with the unit being dead. The regulator's only job is to
lower the 12v adapter voltage to 5v so it can run the unit without
smoking it yet again. The real damage remained at that point unseen,
and might have plagued me MUCH longer except that a tiny glint of
copper caught my eye between the power and filter switches, and on
closer inspection I discovered that it was another heat stressed part
of the board. I very gently removed a large diode that this heat
stressed trace ran beneath, and discovered much to my joy that it was
completely burned in half. I then took a small piece of wire and
completed the circuit with external batteries powering the unit, and
presto, it powered right up, and ummm... stayed powered even after I
removed the jumper wire. It must be a flipflop type of power on/power
off toggle.

Maybe you had it switched on for long enough to partially recharge the
battery???

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

THANKS both of you for helping me!! Now all I need is a new regulator
IC and some VERY delicate work to repair that melted trace, and I'll
be all set! :-D

Rick



a trick i learned long ago was to use bare 'wire wrap' wire to repair the
thin traces. i don't know how commonly available it is anymore. one spool
lasts approximately one lifetime if used only for repair work.