OT: yamaha rex50

[mat]

Hi!

I thought i might ask You peaple an advice for the yamaha rex50 multieffector i bought some 20 years ago.

It has been on the back of the shelf for about 10 years. I picked it up yesterday and tried it.

It works ok despite the problem that it has no more the distortion effect it had earlier and with just every other effect (delay,reverb,chorus,octave,comp..) in the end of the note the sound dies very ugly and disappearing suddenly - like there would be a noisegate on all the time. And there is this faint distortion sound on the backround always - eaven when bypassed  

The battery is also 20 years old and i have all the old patches in in still  :shock:

the picture of the innards:




any idea would be mostly welcome  
cheers,
mat

[mikeb]

Replace all the electrolytics, inspect and touch-up any solder joints that look dodgy then report back!

Hmmm ... you don't live near the ocean, do you? I can see what appears to be rust in there....

Mike

[RickL]

Dryed up/leaking power supply caps maybe? The symptoms sound a little like low voltage at the chips. The kill-a-fly-with-a-sledgehammer approach would be to replace all the electrolytic caps with new ones.

[mat]

All right, i'll counted 15 of them. I'll start to change them. First got to get the pcb off of the bottom plate.

Thanks for the quick one  

mat

[mat]

Ok, i'll change the power caps first. In the picture there is something underneath and in between the caps. Maybe it is some kind of a cooling paste or glue  :roll:  don't know..

mat

Dryed up/leaking power supply caps maybe? The symptoms sound a little like low voltage at the chips. The kill-a-fly-with-a-sledgehammer approach would be to replace all the electrolytic caps with new ones.

[mat]

Hi,

I have changed the power section electrolytics but no difference in sound. Maybe little clearer sound but there is the always present distorted sound that i hear when the note is fading. When I put the circuits volume up, the faint distortion sound does not get louder.

The actual distortion effects are not working.

Maybe some ic that handdles the distortion has broken ?

Well I wouldnt like to tear this down (for the parts). If someone has ideas for further investigation, please tell me.

mikeb, the brown stuff is actually some kind of lacquer, not rust (tho' I live by the sea..)

cheers,
mat

Replace all the electrolytics, inspect and touch-up any solder joints that look dodgy then report back!

Hmmm ... you don't live near the ocean, do you? I can see what appears to be rust in there....

Mike