problem with falcon sound

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Joined: Sun Apr 10, 2005 2:37 pm
Location: Italy - Torino

problem with falcon sound

Post by Gatsu »

Hi to all,
Sorry for my bad bad english!

My Falcon have a Big problem, the sound output is broken

the computer work great, but have no sound.
No sound from internal speaker, and no sound when i connect it via HIFI.

Falcamp give me an error message, when try play mp3,

No sound when play games, and no sound from keyboard press... ecc

the computer so is equipped: Falcon + CT63

What can be happened?

please help me

Thank's in advance

Falcon CT60 + MagicMAcX, Calamus SL2006
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Fuji Shaped Bastard
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Joined: Mon Jul 30, 2007 10:26 am
Location: South West, UK

Re: problem with falcon sound

Post by nativ »

You might try running Ace or another piecee of Falcon music software. Are you using Aniplayer to do MP3's?

Also look for Iphegeny? Which is a util for the Falcon sound system.

Best wishes

Atari STFM 512 / STe 4MB / Mega ST+DSP / Falcon 4MB 16Mhz 68882 - DVD/CDRW/ZIP/DAT - FDI / Jaguar / Lynx 1&2 / 7800 / 2600 / XE 130+SD Card // Sega Dreamcast / Mega2+CD2 // Apple G4 ~ ~ ~

Re: problem with falcon sound

Post by simbo »

if all sound has failed it is most likely a faulty regulator or opamp and not the sound codec ic u28
it controls all sound output like psc fm and dsp interactions

perhaps it is faulty but i dont think so
im sure this could cause the locked thing
did you test the external port also

did you also try to press ALT before it boots
to bypass the hard disk and load plain tos ???
then try a key click test
perhaps some acc locks the sound {im not saying your daft ... :( }

there is a 9 volt regulator that supplies the final output opamp's
and mic circuit {audio in}
u8 behind the scsi2 port looks like a transistor

if this fails there will be no speaker or sound from the tv
and the small 3.5 mm wont produce sound nor will there be audio in
but the machine will still function perfectly
so its worth checking the 9v supply will be a 78L09 3 pin ic

you can find the LM386 u22 and u23 {prob not these } or u21 LF347 and or u9 LM387 {most likely u9 or u21}
amplifier ic's can fail and this pulls the 9v supply down
and this disables the whole sound stage
its more likely just one has failed
and this will turn the regulator off {safety feature}

so this regulator package has three pins
1 ...............2............ 3
out{9v} ground{0v} in{12v}

if you connect a multi/dc meter black wire to ground somewhere metal like the tv modulator metal box,
and then you can check the two outer pins on the 9v regulator
one will be 12v the other should be 9volts
if its not
cut the 9v pin side {not the working 12v pin }
and test at the package end of the cut one again
if the voltage is there now and 9v shows
there is a shorted opamp or a short low resistance somewhere in the 9v supply rail and nothing too serious
{ i suspect this more than the codec !!!}
you should after cutting and 9v reappears on the ic pin turn off

then use a multimeter set to diode test range {most cheep lcd meters have this range}
test from the pcb end of the cut pin and ground
you should get a reading with black on ground and red on the pcb cut end
~1000 turn the leads round you should get open circuit
or you can safely use the beep test range

and sort of beep for longer than 2 seconds
then there is a gubbed ic

to find shorts i use a low resistance range and test at the power supply pins of the ic's
where the lowest to ground resistance is
is the short ic

power in pin on opamps is pin 6 for LM387
and pin 4 LF347 this 14 pin ic are like this 14 13 12 11 10 9 8
.......> notch 1 2 3 4 5 6 7

for 8 pins LM387 8 7 6 5
.......>notch 1 2 3 4

occasionaly you can find one of the axial {tube like } electrolytic caps
is placed with the positive end that can short on the negative metal case
in the picture below is two marked with squares
the one on the left is an example
ive chased this for 20 mins to find before
so check these capacitors havent got this short
this happend becouse the plastic shrinks {becouse its shrink to fit plastic they use}
even in summer its hot enough to shrink these sleaves
just bend it over a little !!
as if by magic the sound is back
easily done if you knock them when your inside
or by a sudden bump when its on its side

the bigger one near the bottom right of the picture
is a resoviour capacitor that gets charged with 9v
so can also go short circuit or leaky

these parts can easly be replaced from above with no need to strip the whole pcb out
beware that sometimes falcons can have modified audio stages
if poorly done this can cause this issue
the usual one is people use insulating tape to protect from shorts
then it dries out over time and falls out when you turn the atari on its side

then when the atari goes flat and something shorts undeneath the pcb
so check supply regulator and for shorted 9v rail

so there is your expos
lets see what it is
if you need the schematic you can find it here ...

pages 10 and 8 are the guys to look at
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