Kyocera receiver not remembering stations

[David Nebenzahl]

Question is about a Kyocera R-851 receiver, ca. 1985, 85 w./channel.
Unit is in fine condition (many capacitators have been replaced) except
for one thing: it doesn't remember radio stations.

This receiver has 7 "presets" each for AM and FM. These can be set, and
the unit will remember them so long as the power is on. Leave it
overnight and the settings are gone.

I'm ASSuming that these are stored in memory that may have battery
backing. Opening the unit reveals no such battery/cell.

Does anyone know enough about this unit to tell me what the likely
culprit is here? Any links to schematics?

Any help would be much appreciated.

 

[David Nebenzahl]

Well that's why, the battery is missing!

D'oh! I knew it.

Alright, now, any *serious* answers?

 

[David Nebenzahl]

Sorry couldn't help myself. A schematic would help find what
keeps the volatile RAM powered up during off time or power failures.

A "super cap" may not last long in 1985 circuitry. They tended to use
rechargable nicads back then like the 3.3v button cell battery pack I
just replaced in a mid-80's Peavey guitar effects processor that loads
into writable memory a patch list pulled from NVRAM when reset to
factory patches.

Get some light and inspect it closely if you haven't. It may have a
super cap depending on how long they designed it to be powered down.

Someone else in another newsgroup (rec.audio.tech) also suggested a
supercap. But it turns out to be a battery after all (actually a 3-volt
Li-Mn cell labeled "LF-1/2 W"; anyone heard of that chemistry? I haven't).

I'm going to the local electronics store to see if they have a
replacement cell.

 

[PeterD]

Sorry couldn't help myself. A schematic would help find what
keeps the volatile RAM powered up during off time or power failures.

A "super cap" may not last long in 1985 circuitry. They tended to use
rechargable nicads back then like the 3.3v button cell battery pack I
just replaced in a mid-80's Peavey guitar effects processor that loads
into writable memory a patch list pulled from NVRAM when reset to
factory patches.

Get some light and inspect it closely if you haven't. It may have a
super cap depending on how long they designed it to be powered down.

Also look for a square/rectangular box like thing, about 3/4" x 1 inch
usually black in color.

 

[Phil Allison]

"David Nebenzahl"

Someone else in another newsgroup (rec.audio.tech) also suggested a
supercap. But it turns out to be a battery after all (actually a 3-volt
Li-Mn cell labeled "LF-1/2 W"; anyone heard of that chemistry? I haven't).

See:

http://uk.farnell.com/varta/6127501301/battery-1-2aa-axial-3v/dp/463292?Ntt=463+292





.... Phil

 

[David Nebenzahl]

Question is about a Kyocera R-851 receiver, ca. 1985, 85 w./channel.
Unit is in fine condition (many capacitators have been replaced) except
for one thing: it doesn't remember radio stations.

This receiver has 7 "presets" each for AM and FM. These can be set, and
the unit will remember them so long as the power is on. Leave it
overnight and the settings are gone.

I'm ASSuming that these are stored in memory that may have battery
backing. Opening the unit reveals no such battery/cell.

But of course, as readers of this thread know, further investigation did
in fact reveal a battery (3-volt Li cell).

Clipped off the old cell (it was attached to the board with little
spot-welded-on "legs"). Found a very similar cell in my battery
collection (flat 3-volt Li large "hearing-aid" style cell). Soldered a
couple wires to it, soldered it to old battery connections, wrapped it
with electrical tape and tucked it into a slot behind the front panel.
The receiver now remembers all presets.

By the way, wasn't there a thread here recently about the difficulties
of soldering connections to such batteries/cells? I had no problem at
all; I cleaned up spots using fine sandpaper (320-400 grit silicon
carbide), then used my old non-lead-free solder and a clean tip on my
iron. Connection was bright and solid.

 

[William Sommerwerck]

It's interesting how many expensive products (and I'm including devices that
sell or sold for over $1000) use soldered-in backup cells, rather than a
battery holder. The battery in a product that gets regular use will often
last long behind its nominal life (10 or 15 years, versus 5), but that's
still no excuse. Indeed, one of the advantages of using a socket is that you
can replace the cell /while the unit is operating/.

My hall synthesizers use a lithium coin cell for backup, and I've replaced
their soldered-in cells with sockets.

 

[Cydrome Leader]

Hi!


Well, I'd wonder if there is a battery compartment on the unit
anywhere. Not trying to be disrespectful or anything, just saying that
a lot of older equipment used conventional batteries (AA/AAA cells) to
keep the memory running.

I have a Pioneer SX-5 stereo receiver that uses two AA batteries.
Lifetime seems to be around a year or so.

William

hillarious. I was just about to mention that stereo when AA batteries were
mentioned.

do you know what the weird "AM stereo" RCA jack on the back is for?

 

[Cydrome Leader]

Hi!


Dunno. I've got a Fisher tuner based on a Toshiba chipset (a 4-bit
microcontroller with integrated memory and a separate display driver)
that uses a supercap to keep the memory running.

Does is seem pretty common for those older supercaps to leak what looks
like machine oil?

 

[William Sommerwerck]

Do you know what the weird "AM stereo" RCA jack

on the back is for?

It's likely for a stereo AM adapter.