Yamaha PSS-480

[phanoo]

hello

I am french, sorry for my bad english... 

I bought today this synth for 8€, I have never done circuit-bending. but on this little keyboard, I would like to add some functions (effects on the sound and/or effects on the rythm (it has nice sounding drum sounds inside!)).

I opened the keyboard, and searched according to the chips references I saw, but most of them gives me no result in google...

ref	name written on the pcb	type
YAMAHA YM 3419B	"RYP7"	SMD
YAMAHA YM 3420B	"OPU"	SMD
A203 87E25 XE415A0	"Gate Array"	SMD
YAMAHA XF305D0	2M ROM	DIL
8831EX XE402AO-611	1M ROM	DIL
TOSHIBA TC5565APL-12	64k RAM	DIL

I can give photos if you want.

I don't know what is the FM IC and Rythm IC... I mean the 1st and 2nd, but i'm not sure.

Is there someone who has already bent this keyboard could give me some info about what I can do on this keyboard ?
I'd like to modify the drum sounds 

[phanoo]

I tryed to find points around the 1MB ROM chip, I did some contacts between a few pins on the chip:


the 9 points I tested seems to be data lines between the ROM and the YM3419B chip.

Some sounds I got are quite funny ^^
Some connections make a bug that plays the entire content of the PCM memory, I listened to this and I think some of the sounds in the memory aren't usable from the keyboard. I listened to 4 different tom sounds (with a very lot of noise), and the 2 high toms are unused... maybe I will found a trick to use them !! 

you can listen to the drums here: http://xiwav.free.fr/Samples/q.mp3 (first, you hear the normal playable drums, next the bug that plays an infinite loop of all sounds)

[phanoo]

Yesterday, for a little 24hours composing competition, I made a song entirely with this keyboard: http://xiwav.free.fr/fete_a_la_saucisse.mp3
that shows you the possibilities of this thing 

[Circuitbenders]

I think theres some details on the PSS480 in the really long Yamaha PSS thread on this forum http://www.circuitbenders.co.uk/forum/index.php/topic,99.0.html

or at least some people have already bent it.

[kick52]

Yeah, playing all of the ROM happens alot on some keyboards, Casio/Yamaha for example when you short the clock.

[phanoo]

oh it's really hard to find stable bending points (I want something that can do music, not only random glitches ^^).

actually i've found 1 very interesting bend on the rythm IC, it makes hardcore drums and seems to be very stable (I can switch it on/off while playing without any bug). It's by connecting together the pins 4 and 7 of the first line of the rythm IC (sorry for my bad expression...).

I will add on this topic everything I discover on this synth 

[phanoo]

hello

I've made 2 interesting bends !!

the first: a switch that mades very punchy drums, you can listen here: http://xiwav.free.fr/pss480drums.mp3 (first you hear the normal drums, next the modified drums)

the second: I added the possibility to use the synth as a portable amplifier !! I connected a female jack to the right pins of the amp, with some resistors between, to reduce the input signal).
It's very useful, for example to amplify the music of your MP3 player. it's also possible to play the keyboard and listen to music at the same time 

some photos:
the little blue switch at the right hand corner is for the drums:


the jack input:


photo of the pcb (if u want to reproduce my bends...)

for the amp mod:
red cable = ground
two black cables = left/right signals from the jack
for the drum mod:
a switch is connected to the 2 cables

[phanoo]

today I added 2 tweeters, because the original speakers don't makes any high frequencies...
I connected the tweeter in 'parrallel' (not in serie [sorry if it's not the good word in english...])

the original speakers : 4 ohm
my tweeters (got on an old TV): 16 ohm

(16x4) / (16+4) = 3 ohm

that's maybe a bit low for the amps, but for the moments it works well, the amps don't become hot...

[iwillbeacircuitbender]

Like you said, the YM3420B is the FM chip