Need help/service manual for Yamaha C-70 Preamp

hi all,

my borrowed C-70 stopped working a few days ago. i jiggled the connections on back - just a slight buzz through the speakers - so there's no signal going to the amps. everything lights up as usual. i used another preamp and the rest of the system works fine.

i know the relays can get squirrley and also the RCA jacks on back. no harm in spraying some deoxit, right? on the relays too?

anybody have the service manual or schematic? my friend is an awesome tech.

i suppose while he's in there, he might as well replace the old power supply caps. any modern equivalents for the chip-sets? i figure there's MUCH better op-amps these days, eh? any drop-in replacements?

i need to get this bad boy running again - it's the greatest phono stage I've heard (with-in reason of course - but still very impressive). maybe a touch of grain up top (1980's op amps) BUT extremely dynamic and tight. definitely none of that usual low-end muffled analog sound.

BTW - i sold my mint C-80. sounded nice - but there is something very special about the C-70. especially the disc direct phono stage. also, the C-70 uses relays instead of push buttons. it's also simpler with none of the variable loudness crap like the c-80. uses an Alps blue velvet instead of the nightmare 6-gang unit.

this unit is in okay condition - some scratches and stuff, but hey i can't complain. my friend said if i fix it - i can have it ;-)

Thanks Mike!

i downloaded the C-80 schematic. looked on the site, but no C-70. there are lots of similarities between the two. we'll see if the C-80 schematics is good enough.


mikemaniak said:
In case this can help, I just downloaded Yamaha c-80 schematics here:
I have a c-60 to fix, maybe when I retire...

Good luck