On 4/21/2010 1:10 PM Meat Plow spake thus:

On Wed, 21 Apr 2010 12:46:35 -0700, David Nebenzahl
wrote:

On 4/21/2010 12:40 PM Meat Plow spake thus:

On Wed, 21 Apr 2010 12:18:03 -0700, David Nebenzahl
wrote:

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.

Well that's why, the battery is missing!

D'oh! I knew it.

Alright, now, any *serious* answers?

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.



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