Sony Mini Hi-Fi Radio Station Memory Loss

[Jerome Halphen]

Good day, Gentlemen,

I've got a Sony PMC-D307L mini hi-fi combo (AM/FM radio, CD, Cassette) which
is about 6 years old. It used to retain programmed radio frequencies for a
couple of hours or more during a power outage, but now any loss of AC power
wipes the memory immediately.

There is no user-replaceable backup battery, and i don't know if this unit
uses internally a Ni-Cd battery, a lithium cell or a 1 Farad capacitor. I
have no schematic either.

Any help greatly appreciated to restore this unit back to its original
memory retention performance.

Thank you for your help,

Best Regards

jhalphen at dial dot oleane dot com

 

[[email protected]]

Hmm there's a schematic for a CFD-S38L in PDF format at:

http://www.promelec.ru/scheme/CFD-S38L.pdf

It uses the same mechanism as the PMC-D307L. It shows a 6 V, 4X AA for
memory backup .

Richard

 

[Jerome Halphen]

Hello Richard,

Thanks for the link to the radio/cassette schematic !
The physical aspect of PMC-D307L is in the shape of a shoebox standing on
end with separate speakers.

I can't believe though that regular (and possibly leaking) AA batteries
would be used for backup INSIDE a piece of equipment, and requiring
disassembly to reach them, when it's so easy to have a small user-accessible
hatch to locate the batteries. Did Sony do THIS !

Thanks again & Best Regards

jhalphen at dial dot oleane dot com

 

[[email protected]]

I personally have never seen this unit but I'm pretty sure that the
memory backup batteries are externally accessable. It was the only
schematic I could find and I thought it would give you a clue as to
the location of a memory backup system. If you follow that trace out it
supplies B+ to the system chip which makes sense and would be the first
place to look for a cap that would be memory backup. (your discription
doesn't sound like a lithium )

Richard