Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Default Bearcat BC855XLT Loosing Memory

Hi,

I have a Bearcat BC 855XLT scanner (scanning radio) in my service shop.
No schematic. The radio lost all it's memory, but I was able to reprogram
some of the channels and the radio works.

The OM says, "A unique capacitor type memory back-up eliminates the need
for batteries". I suspect that maybe this capacitor is going bad(?), but
since I don't have a schematic, I have no idea where this capacitor is
located.

Thanks in advance, Brad

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Default Bearcat BC855XLT Loosing Memory


Brad wrote:

Hi,

I have a Bearcat BC 855XLT scanner (scanning radio) in my service shop.
No schematic. The radio lost all it's memory, but I was able to reprogram
some of the channels and the radio works.

The OM says, "A unique capacitor type memory back-up eliminates the need
for batteries". I suspect that maybe this capacitor is going bad(?), but
since I don't have a schematic, I have no idea where this capacitor is
located.



The is a type of RAM called CapStore. It was a common static RAM,
with some flash memory. It detected a power loss and stored the
contents in the flash memory, and on power up, wrote it back to the
static memory. We used it to replace the 2k * 8 battery backed RAM in
our products.

http://www.zmd.de/pdf/CapStore.pdf

http://www.google.com/search?q=capstore+ram&rls=com.microsoft:en-us:IE-SearchBox&ie=UTF-8&oe=UTF-8&sourceid=ie7&rlz=1I7GGLD


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Default Bearcat BC855XLT Loosing Memory

Michael A. Terrell wrote:

Brad wrote:

Hi,

I have a Bearcat BC 855XLT scanner (scanning radio) in my service shop.
No schematic. The radio lost all it's memory, but I was able to reprogram
some of the channels and the radio works.

The OM says, "A unique capacitor type memory back-up eliminates the need
for batteries". I suspect that maybe this capacitor is going bad(?), but
since I don't have a schematic, I have no idea where this capacitor is
located.




The is a type of RAM called CapStore. It was a common static RAM,
with some flash memory. It detected a power loss and stored the
contents in the flash memory, and on power up, wrote it back to the
static memory.


snip

If not this device, then perhaps you have static RAM with standby power
from a supercap (perhaps about 1F). Look for a squat round package which
looks a little like an electrolytic or a battery cell encased in plastic.
I have a scanner so equipped and have seen supercaps used in many
handheld and ruggedized devices where battery (cell) changeout would
be difficult.

Michael
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Default Bearcat BC855XLT Loosing Memory

If it's loose, tighten it.


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Default Bearcat BC855XLT Loosing Memory

The manual states the memory backup is only good for up to 3 days with
no power.


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Default Bearcat BC855XLT Loosing Memory

On 16 Set, 23:59, Ken Layton wrote:
The manual states the memory backup is only good for up to 3 days with
no power.


I have an old digital radio tuner with 8 presets. Its memory is kept
out of a standard 470uF capacitor, probably very low consumption SRAM
and lasts a few weeks.
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Default Bearcat BC855XLT Loosing Memory

On Mon, 15 Sep 2008 13:08:01 GMT, (Brad) put
finger to keyboard and composed:

I have a Bearcat BC 855XLT scanner (scanning radio) in my service shop.
No schematic. The radio lost all it's memory, but I was able to reprogram
some of the channels and the radio works.

The OM says, "A unique capacitor type memory back-up eliminates the need
for batteries". I suspect that maybe this capacitor is going bad(?), but
since I don't have a schematic, I have no idea where this capacitor is
located.


There are some Uniden Bearcat service manuals he
http://www.mods.dk/manual.php?brand=uniden

Your model's SM is not listed, but maybe a similar memory backup
scheme is used in other models. Be aware that the above site allows
only one free download in 4 days.

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Default Bearcat BC855XLT Loosing Memory


"Brad" wrote in message
...
Hi,

I have a Bearcat BC 855XLT scanner (scanning radio) in my service shop.
No schematic. The radio lost all it's memory, but I was able to
reprogram
some of the channels and the radio works.

The OM says, "A unique capacitor type memory back-up eliminates the
need
for batteries". I suspect that maybe this capacitor is going bad(?),
but
since I don't have a schematic, I have no idea where this capacitor is
located.


I would hope the capacitor would be located inside the radio, where else
would the mother****er be?

What makes you think that it's the capacitor? It could be the resistor
connected in series with the mother****er or the memory chip itself going
bad.

Thanks in advance, Brad

Before you type your password, credit card number, etc.,
be sure there is no active keystroke logger (spyware) in your PC.



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