"RJH" wrote in message
...
On 19/02/2016 08:45, Woody wrote:
"RJH" wrote in message
...
I've taken the cover off, and noticed the battery seems to be
leaking slightly:

https://flic.kr/p/EdXFsh

There's a white furry deposit around what I assume to be the
battery - the blue thing centre top. The underside of the circuit
board looks fine.

Is a replacement straightforward? I can solder after a fashion.

A recommended source for a replacement? A google search throws up
quite a few options.

Would I be best not using it until the replacement's in?


Phil is right but I would wait until you have extracted it before
buying a replacement as it could be Ni-Cad or Ni-MH depending on
the
age of the tuner, and they require slightly different charging
regimes. Equally it could be 3V, 3.6V or 4.8V although I would
admit
that the size suggests the latter.


OK, will do, thanks (and Phil).

You can removed the battery and clean the PCB and then continue to
use
the tuner - it will just not remember memory settings when powered
down. Having said that it takes little power so you could just
leave
it switched on. Do however make sure that the battery wires are
insulated after you remove the battery but before use. Also take
care
unsoldering - remove the negative (black) first so that if you
accidently short the positive to chassis northing will happen:
Ni-MH
batteries (if that is what it is) can supply quite a bit of current
for a short time.

Have a look at
http://cpc.farnell.com/webapp/wcs/st...1541,110151587
who stock just about every type you might need. Maplins also stock
some but only a limited range and possibly a bit more expensive.


Great, thanks.

However, another problem. The tuner is new to me, and I'm told it
was working quite recently. However, I can't get any sound out of
it. The signal bar is showing 7/10 and the stereo light is on, so
I'm guessing that's enough?

Also, the memory store (hold Tune down and choose a preset) isn't
working. I'd think this might be down to the battery, although the
previous owner's presets can be recalled quite merrily - most with a
5-6/10 signal.

Might this be to do with the strength of the signal - I'm just using
a table top FM aerial. Or something more serious, do you think?



Change the battery first. If it is low and cannot charge it may be
pulling down the supply rail which is preventing other things from
working properly. The battery is 4V.

The audio output has a mute circuit on it for start up to prevent
noises - it could have something to do with lack of sound. If the
aerial is connected, you are showing a signal, and the stereo beacon
is lit it shows the tuner has enough signal. This may also be an audio
stage electrolytic capacitor problem - see the next paragraph.

I suggest you look at this video
https://www.youtube.com/watch?v=RXVuPcNLyWw
and read the first comment beneath. The 'electrolytics' are the
smoothing capacitors in the power supply and they dry out with age.
They are 1000uF (microfarad) each probably 35V or 45V or 63V. Such
components are easy to obtain.

If you go to
http://elektrotanya.com/quad_fm4_sm.pdf/download.html
you can download the manual - which includes the circuit diagram -
free of charge.

If you bought the tuner on eBay as working then I would suggest before
you do anything to it you start a grievance procedure. If you know
what you are doing they are easy enough to fix, but for a tuner of
that age a rather more comprehensive reworking may be needed.


--
Woody

harrogate3 at ntlworld dot com