"Mike" wrote in message
et...

"Radiosrfun" wrote in message
...
Anyone here with "in-depth" knowledge of the Bearcat 250 Scanner and
repairs? I am way out of tune with these things. Haven't seen one - let
alone worked on one for close to 10 years if not much longer. I have a
model
here just came in the door for repair. I've had a manual from days gone
by.
There appears to be some differences - not shown in the manual. I'm
wondering if I can pick someone's brains about this model or it's
differences.

1. Was there more than one version of service manual? At the time I
purchased this, I don't believe I was told of anymore than the one - I
usually ask about revisions.

2. Did the updates in this model produce differences in circuitry (I'm
sure
they probably did) - and how?

3. The issue I "currently" see - is I have "low level" audio, no squelch
action, no receive, no display, no dot. I started troubleshooting it and
this book has a Q206 listed in it as providing a particular voltage to
the
circuit (can't recall which part of the circuit - without the book in
front
of me). THIS unit shows NO Q206 where the book shows it to be. I can be
more
specific in parts layout in that area if someone asks - but for now -
I'm
missing some voltage and need to find out why Q206 is not there OR
whatever.
The "Q204" is putting out like 4 - 6 volts less than it should. I'm not
sure
that is the "only" issue here - but the first I found thus far. I'm just
trying to clear up the mystery of Q206 for the moment. The book shows it
"supposedly" on the "Features" board. Along with that issue, there is in
the
same leg of circuit - according to my manual - a 47K ohm resistor there
tied
to Q204 and a wire coming from the 18V supply - with an 9v Zener in that
area also. This model has a 1xxxx ohm resistor there OR at least it
appears
to. It is burned in the center from heat - but the first band is clearly
"brown" - so this isn't the 47K as called for in my manual. Basically,
the
circuit leg is all there - minus Q206! There's not even a place for it
"to"
be, from what I'm seeing.

IF I'm in error of voltages/values specified - its' only I'm going from
memory - the book is in the shop - but I"m not off in my description
otherwise.

I can provide more specific info such as Serial Number, Board numbers
and/or
revisions, whatever - if requested, I just don't have it in front of me
at
the moment.

I realize some parts of this radio are impossible to get now-days - so -
I
want to make sure I can trace this down to something repairable and get
it
done OR find out quick it isn't possible and hand it back without
wasting
much more time.

Any info? Please answer here - my address is a spam catcher only.

Thanks,

Lou



Lou, maybe this info will help.

In looking through my Bearcat info, I found a schematic for a "250A". The
feature board is constructed a little differently than what they show in
the
250 service manual and I have seen both boards used in 250s. The red wire
still goes to the collector of Q204 (NPN). The emitter of Q204 should
have
8.4 Volts there. The base circuit of Q204 is a little different on the
"A"
version. A 9.1 Volt 1 watt zener runs from the base of Q204 to ground.
(Cathode connects to the base of Q204). Now, the collector of Q206 (PNP)
connects to the base of Q204 through R239, a 150 ohm 1/2 watt resistor.
That's the only connection on the collector of Q206. Q206's base has
R220,
a 100 ohm 1/2 watt resistor that is connected to the cathode of D212, a 10
Volt 1 watt zener.

Hope this info helps you out. Keep us posted on your progress.

Mac



Sorry, I forgot to mention in my first response that the emitter of Q206
connects to the collector of Q204 (the red wire - 16 volts). Meanwhile, I
found another schematic for the 250 that shows the same circuit I described,
but also adds one resistor on Q206, between the emitter and base. The
resistor is labeled R242 and is a 1K 5% (wattage is not indicated).

Do you have the correct voltages at the output of the switching power
supply? (plus and minus 25 volts). If not, you probably need to diagnose
that problem first. Depending on what has failed there may determine
whether or not the scanner is repairable. If it's just a capacitor failure
(common) or a failure with IC-8 (it happens) then it is probably repairable,
but if the problem goes on back to IC-9, IC-7, or IC-6, the prognosis is not
so good.

Good luck!
Mac