problem with marion systems prosynth

trans alp · Joined: Apr 19, 2012 Posts: 2 Location: dresden/ germany

hi, this is my first post here ...

i was searching for a marion pro synth for a very long time and finally managed to buy one. the seller stated the synth as NOS and it looks so.

there is only one thing that is annoying ... there is a high frequency "hiss" on four of its eight voices. for example ... when i turn down the filter cutoff to a low value - so that only a sine-like waveform can be heard - there is that high hiss on voices 3/4 and 7/8. it sounds like the high freq portion of the base waveforms is leaking through. this happens on any preset ... so it seems to be an hanrdware issue.

i took a look inside and checked the ic sockets. the only thing that looks not normal is that some of those (many) yellow caps (they are "blob" shaped and i guess they are the ceramic type) in each voice seem to be a bit leaky ... but this also could be just some solder flux. unfortunately i have no camera to docuent this.

is there anyone around who is familar with the marion systems pro synth an experienced something similar or can help me track down the error otherwise?

thanks in advance,
sebastian.

drapdap

hi sebastian!

just read your post. i have a marion msr-2. maybe i can help.
i'm not knowlegable at all when it comes to these beasts, but mine is working properly after changing the psu caps and a full reset. im such a happy chap...

could be you have an issue that unit has been switched off for too long, and the power supply is not up to driving the unit properly anymore?
but hard to tell.
the bleed thru are the high frequency drivers for the vco?

measure the psu. i'd start there, rather than messing with the voice board.

robert

trans alp · Joined: Apr 19, 2012 Posts: 2 Location: dresden/ germany

hi robert, thanks for the reply.

i just have some basic knowledge in electronics, so i checked the caps on the psu only optically and measured the output voltages - wich have the correct value (as printed on the pcb). only one thing was wrong there - there are two voltage regulators (i guess) and one of them had a loose cooling element. is there anything else to check on the psu?

it really could be, that it was switched off for too long. i guess it never ever has been used before.

well, about the bleed thru ... i'm not even shure if it is one Embarassed

it also could be distortion. in fact, when i turn down the cutoff, there are some high overtones, that are not supposed to be there. i can make an recording if it halps ...

sebastian.

drapdap · Posted: Wed Jul 31, 2013 5:50 am Post subject: