Discussion:
Did I brick my 780?
xray@outgun.com [UnidenBC780XLT]
2014-09-21 19:17:34 UTC
Permalink
I mainly use my 780 for P25 reception via discriminator tap and it worked very well for that purpose. Today, I uploaded a few new freqs to it via Proscan and now I receive nothing, no reception, just background noise. All functions work fine but no reception, any band. I did the 2/9/man reset but no joy. Do I now have a pretty boat ancher to use on my next fishing trip?
'Tom Hirsch' thirsch4@juno.com [UnidenBC780XLT]
2014-09-24 16:03:47 UTC
Permalink
Hello from Florida,

Sorry to hear of your problems with this great legacy scanner.

1. You can try another reset.

2. We assume that the frequencies you programmed are all active and you are hearing comms on these freqs on other scanners when your 780 is receiving nothing. Are you seeing anything on the signal strength bars on the 780? Make sure the correct frequencies are programmed in the correct mode (AM, FM). Try the service search mode, and see if you receive anything, including using FM broadcast.

3. Make sure you have the attenuator deactivated.

4. Check the BNC connector on rear of unit. Generally, these us a "fork" type contact inside the connector, and over time, the fork pins can bend outward so they no longer make contact with the pin of the BNC antenna connector. If that's the case, very carefully us a needle to press the pins of the fork inward so they contact the pin of the BNC connector.

5. Repair may be an option. Uniden no longer supports this model with parts or service. However, you can contact G & G Communications in New York, who repairs old and new scanners: http://www.gcomradio.com/

5. If the scanner is undamaged physically, I and other 780 loyalists would be interested in buying it for a reasonable price to use parts to fix our 780s that don't work. If you decide to sell the 780, please advise your friends on this list, and I'm sure you will find a buyer if the price is reasonable.

Good luck
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If you have come here to find out about the Uniden BC-780 you have come to the right place! In fact the discussion of the BC-780 is the only acceptable topic on this list. Please. I hope this is clear to all group members.
Rich Carlson rich.n9jig@gmail.com [UnidenBC780XLT]
2014-09-24 18:07:47 UTC
Permalink
Have you tried receiving other freqs? Try the local weather channel or ATIS
and see if you can hear that OK.

Reprogramming a 780 should not cause it to stop functioning unless you
programmed the freqs incorrectly. Remember, as an older radio, the default
modes and step sizes may not line up.

Check to see that the freq is correct and that the mode is right. For
instance, if you try to program 154.4075 it may come back as 154.405 or
154.410, this might be just enough to mess you up. Also Narrowbanding has
arrived since the 780 came out, so many freqs may default to a wider FM,
you may have to specify NFM.
Post by ***@outgun.com [UnidenBC780XLT]
I mainly use my 780 for P25 reception via discriminator tap and it worked
very well for that purpose. Today, I uploaded a few new freqs to it via
Proscan and now I receive nothing, no reception, just background noise. All
functions work fine but no reception, any band. I did the 2/9/man reset but
no joy. Do I now have a pretty boat ancher to use on my next fishing trip?
--
Rich Carlson, N9JIG
'Larry Shumway' lwshumway@frontier.com [UnidenBC780XLT]
2014-09-25 01:54:17 UTC
Permalink
I’m Curious.


What hardware and software are you using with the 780 for receiving P25 ?





thanks





From: ***@yahoogroups.com [mailto:***@yahoogroups.com]
Sent: Sunday, September 21, 2014 3:18 PM
To: ***@yahoogroups.com
Subject: [UnidenBC780XLT] Did I brick my 780?








I mainly use my 780 for P25 reception via discriminator tap and it worked very well for that purpose. Today, I uploaded a few new freqs to it via Proscan and now I receive nothing, no reception, just background noise. All functions work fine but no reception, any band. I did the 2/9/man reset but no joy. Do I now have a pretty boat ancher to use on my next fishing trip?
xray@outgun.com [UnidenBC780XLT]
2014-09-29 00:08:00 UTC
Permalink
I use DSD+ and just tap the discriminator output using a 10mfd electrolytic, + toward the tap. Worked great for many years. I thank I traced my problem to a cold solder joint in the BPF section.
Nicole Rayna Nobrega nickpaq7121@hotmail.com [UnidenBC780XLT]
2014-09-28 20:56:02 UTC
Permalink
Your hardware tap most likely faulted (maybe excess solder, excessive
exposed conductor on the tap, conductive flux residue, failure of tap
conductor caused by using blade-type wire insulator strippers indenting the
wire.) Your best bet is to pull out the schematics and PCB layout datasheets
from your filing cabinet and open the 780. Inspect the discriminator tap,
inspect the areas (with high magnification) on the PCB affected by the tap,
clean, test, and diagnose the hardware. My bet is that the modifications on
your 780 are likely to blame. I have yet to come across an unaltered 780
that has faulted in the way you mentioned. If you want, I am willing to take
a look at your 780 and even repair the issue, and I also can rework your
discriminator tap so that it is done correctly. I have fixed the no display
problem for other members in the group and they can feel free to chime in if
they feel so inclined.



Hope you can get this resolved in a timely fashion, it is a great scanner,
and I would hate to see it land in a dumpster over something so minor.



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xray@outgun.com [UnidenBC780XLT]
2014-09-29 00:20:38 UTC
Permalink
Hello Nicole, thank you for the info. The tap has been working flawless, I seemed to have traced it down to a cold solder joint in the BPF section. Using the blow dryer method I found that heating up the area around the filter parts brings all reception back to life, so it must not be happy where it is and now it wants a warmer climate;o). I will have to get practice with surface mount.
Could be a failing part also. It is the best scanner I ever owned so miss it.

Thanks to all who have answered,

Lew
'Larry Shumway' lwshumway@frontier.com [UnidenBC780XLT]
2014-09-28 23:27:43 UTC
Permalink
I’m Curious.


What hardware and software are you using with the 780 for receiving P25 ?





thanks





From: ***@yahoogroups.com [mailto:***@yahoogroups.com]
Sent: Sunday, September 21, 2014 3:18 PM
To: ***@yahoogroups.com
Subject: [UnidenBC780XLT] Did I brick my 780?








I mainly use my 780 for P25 reception via discriminator tap and it worked very well for that purpose. Today, I uploaded a few new freqs to it via Proscan and now I receive nothing, no reception, just background noise. All functions work fine but no reception, any band. I did the 2/9/man reset but no joy. Do I now have a pretty boat ancher to use on my next fishing trip?









_____


Posted by: ***@outgun.com


_____
Nicole Rayna Nobrega nickpaq7121@hotmail.com [UnidenBC780XLT]
2014-09-30 16:37:51 UTC
Permalink
Hello again,



I am pleased to hear that you have narrowed down the problem. There really
isn't far too much difficulty working with the SMD technology used on the
780. The solder is leaded and the soldering tip should not exceed 650 F at
any point in time when reworking any individual SMD lead. Do not use a basic
wall plug pencil soldering iron as these irons will burn and destroy the
sensitive components and PCB lands/traces/VIAS/etc.

Desoldering braid must be of narrow width and can prove to be frustrating in
the begining. Always practice on scrap PCB boards salvaged from electronics
you are disposing of (maybe that *Bleeping* printer you have sitting about
after choosing to skip buying expensive cartridges for; so instead you
bought a printer on sale to replace it. only to find yourself still paying
too much for ink.).

Tools I suggest you invest in so that you can do radio repair without the
need to build an additional room or dedicate a large space to electronic
repair.

- A NEW Weller WTCPK Soldering kit, these are the best secret out
there, and they have a wire insulation cutting tip which is thermally
controlled. Based on the ingenious magnetic temperature control tip
technology that made Weller one of the few soldering iron manufacturers to
still be around today. Changing the tip allows you to also change the
temperature. Use the 600 F tips on the 780. DO NOT USE A DAMP SPONGE on the
tip, this is a huge NO, Weller tips are plated to last a very long time,
non-Weller tips don't last long. Always tin the tip with solder (Tip tinner
should never need to be used and will damage the tip) after each joint, and
leave a ball of molten solder on the tip when placing back in the pencil
holder or turning off the pencil. Best of all: when everything is cooled
off, the soldering station breaks down, so that you can close the lid and
tuck it away in plain sight. There is a carry handle making this the most
portable soldering station I have ever used.

- Get a Hakko fluxed wire tip cleaner as a smart solution to the
damp sponge.

- Buy a 1 lb. spool of Kester 44 .015 Sn63/Pb37 Solder, this is
fantastic stuff, a single spool will last you a very long time. The
expiration date is clearly marked on the spool making it easy to determine
when you are working with old expired solder.

- Chemtronics Chem-Wik Desoldering Braid is a total must have. As
said previously, narrow width, you want to desolder a single SMD joint, not
the whole SMD. This product makes reworking and correcting solder joint
excessive solder errors rapid and helps prevent overheating the work piece.

- Quick-Chip is a product that I have mixed feelings, however,
there are certain tasks that are made easy when you use this tacky flux.
However, you will find that it leaves your work piece with a residue. It is
also super easy to accidently apply far too much of this product. This leads
me to my next tool

- A good set of dental picks. Use these to apply trace amounts of
Quick-Chip, work a SMD off your work piece, position a SMD on your
workpiece, and a multitude of other situations.

- A good array of tweezers. Not the type you buy for personal
hygiene. You will often find that certain SMD types and the locations they
are installed in require a different grip or angle. I am not a contortionist
and I would be impressed if you are.

- You will want very bright lighting coming from many directions.
Mistakes will be made and damage will be done if you dare to navigate with
poor lighting. You can be creative on this one.

- You will also want magnification. Don't bother with the gimmicky
"helping hand" tool as this will not be practical. You can be creative on
how you get a closer view. I use a lens I salvaged from projection
television set. I have used lenses from disposable cameras, and have had
luck placing a small lens over the camera lens on my phone to create an
improvised microscope. The solution you arrive at will be based on if you
are doing this at home or doing it while on vacation and have not expected
to repair something.

- There are many other items that you may need depending on how far
you want to go and how much understanding you have gained dealing with
electronic repair.

Granted a multi-meter and so on would be ideal, however, I am assuming that
you have a level of proficiency regarding electronics since you are not
afraid to open your 780 (which means you understand basic precautions and
procedure.) I am sure you could teach me several things about electronics
and I am only educated enough to give the aforementioned tool
recommendations based on my experience successfully repairing electronics of
all sizes both professionally and individually. My suggestions are only
worth what you value them at and therefore I assume they are of no worth
unless I'm told otherwise.



Hope you are able to get up and scanning with your 780 soon,

I can't imagine how difficult it must be, there is no radio that I would let
take the place of my 780, it is a wonder how I managed before I purchased
mine.



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-- NOTICE -- The information transmitted is intended only for the person or
entity to which it is addressed and may contain confidential and/or
privileged material, the disclosure of which is governed by applicable law.
Any review, retransmission, dissemination or other use of, or taking of any
action in reliance upon, this information by persons or entities other than
the intended recipient is prohibited. If you received this in error please
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