Yamaha CS-50 All Keys of E not working

Pulling out your hair? Don't know what to do or where to go? Ask in here.
Forum rules
READ: VSE Board-Wide Rules and Guidelines

If your Help request has been solved, please edit your first post in order to select the Image Topic Icon to let others know your topic has been solved.
wizardmix
Newbie
Newbie
Posts: 9
Joined: Tue Jul 04, 2017 7:20 am

Re: Yamaha CS-50 All Keys of E not working

Post by wizardmix » Thu Jul 06, 2017 2:37 am

Mooger5 wrote:Final post for today (yawn).

Part of the KAS PCB layout. Notice the C, C#, D, D# notes and so on. Also notice the multitude of Es! Which one is it? It´s the one that leads to pin 11 of IC1. Notice how all the other Es are linked by jumper wires. I think "E" here, apart the musical note, stands for Earth. They of course meant Ground points. The shields of the wires are soldered to them. The central conductor of the lime green wire is soldered to the relevant E note.
I speculate, but it´s possible during a previous service job some tech soldered the E green wire to one of the Earth points by mistake, if they are labeled in the PCB like they are in the service manual.

Cheers.
Good God Man!! I second Rasputin's comment, waaaay above and beyond brother but extremely appreciated nonetheless. The information has been forwarded, my friend just called me to say thank you so I forward that thanks to you. This will be put to immediate use -- as will the CS50 once it's up to snuff. He won't like that I said this but in the off chance you liked BMSR from the Dandelion Gum era, you helped one of the original members on his birthday no less.

User avatar
madtheory
Supporting Member!
Supporting Member!
Posts: 5114
Joined: Mon May 01, 2006 12:45 pm
Real name: Tomas Mulcahy
Gear: Flangebeast Mk1, Plonkotron, Morovdis Arpeggiator, Maplin My First EQ, Cabaret Voltaire, Jeff Wayne Thunderchild rack, thermostat, Buck Owens Moog.
Band: Minim
Location: Cork, Ireland
Contact:

Re: Yamaha CS-50 All Keys of E not working

Post by madtheory » Thu Jul 06, 2017 11:06 am

Awesome work Mooger5! So we have 3 possibilities:
1. Open circuit caused by dead diode or dry joint.
2. The last person in there confused the note "E" with "Earth" because Yamaha didn't translate the word for "signal ground" as opposed to "Earth" correctly.
3. Rotting CMOS Yamaha custom chip.

Mooger5
Expert Member
Expert Member
Posts: 1422
Joined: Tue May 06, 2008 5:11 pm
Location: Lisbon

Re: Yamaha CS-50 All Keys of E not working

Post by Mooger5 » Thu Jul 06, 2017 10:40 pm

Thanks for the kind words, guys :) Some of the compliments are highly exaggerated haha. Please keep in mind, until further notice, the synth is not fixed yet; the diagnostics may be wrong and if so, the effort was worthless.

By simply using a diode such as 1N4148 it´s possible to confirm right away. With the anode lead, touch one of the octave tabs in the KAS (U1 or U2 etc) and at the same time touch the E-keys tab (E-23 in the KAS PCB) with the cathode lead. The E line should finally trigger a sound. No need to press a key as this simple test bypasses the keyboard.

Image
Herrare umanum est.

Mooger5
Expert Member
Expert Member
Posts: 1422
Joined: Tue May 06, 2008 5:11 pm
Location: Lisbon

Re: Yamaha CS-50 All Keys of E not working

Post by Mooger5 » Fri Jul 07, 2017 9:49 pm

I just thought of an even easier test! This time you don´t need to mess inside the unit: just turn the glissando on and set the time to medium to slow. Hit one key that works (which means every key but the E notes), say C4; then hit one of the keys that don´t work, say E2. If my hunches are right, the glissando function will not aknowledge the second key was hit thus it should not work. Nothing will happen! Ha! Isn´t that great?
IF the glissando works, you should hear the downwards scrolling through every note but the E notes. This would mean everything from the keyboard matrix to the Keyboard coder and assigner is OK, including the famous green wire. It would also mean the problem lies ahead, in the D/A circuit. Let´s hope not...
Herrare umanum est.

User avatar
madtheory
Supporting Member!
Supporting Member!
Posts: 5114
Joined: Mon May 01, 2006 12:45 pm
Real name: Tomas Mulcahy
Gear: Flangebeast Mk1, Plonkotron, Morovdis Arpeggiator, Maplin My First EQ, Cabaret Voltaire, Jeff Wayne Thunderchild rack, thermostat, Buck Owens Moog.
Band: Minim
Location: Cork, Ireland
Contact:

Re: Yamaha CS-50 All Keys of E not working

Post by madtheory » Fri Jul 07, 2017 10:37 pm

Now that's clever. People pay good money for techs who are scientific y'know! :)

Mooger5
Expert Member
Expert Member
Posts: 1422
Joined: Tue May 06, 2008 5:11 pm
Location: Lisbon

Re: Yamaha CS-50 All Keys of E not working

Post by Mooger5 » Mon Jul 10, 2017 9:17 pm

I´m only in this for the passion for vintage synths and the education.
Herrare umanum est.

User avatar
madtheory
Supporting Member!
Supporting Member!
Posts: 5114
Joined: Mon May 01, 2006 12:45 pm
Real name: Tomas Mulcahy
Gear: Flangebeast Mk1, Plonkotron, Morovdis Arpeggiator, Maplin My First EQ, Cabaret Voltaire, Jeff Wayne Thunderchild rack, thermostat, Buck Owens Moog.
Band: Minim
Location: Cork, Ireland
Contact:

Re: Yamaha CS-50 All Keys of E not working

Post by madtheory » Tue Jul 11, 2017 12:51 pm

Ya, that was a compliment :)

Mooger5
Expert Member
Expert Member
Posts: 1422
Joined: Tue May 06, 2008 5:11 pm
Location: Lisbon

Re: Yamaha CS-50 All Keys of E not working

Post by Mooger5 » Tue Jul 11, 2017 8:06 pm

Thanks. Damn Catholic tradition. I´ll never be rich :D
Herrare umanum est.

meatball
Newbie
Newbie
Posts: 11
Joined: Wed Oct 03, 2018 5:09 pm

Re: Yamaha CS-50 All Keys of E not working

Post by meatball » Wed Oct 03, 2018 5:17 pm

I wonder if i might ask to exploit that 'catholic tradition' further - i'd certainly be happy to forward the good deed ... :P

i have a related problem on my CS50 that has taken me to the brink of my troubleshooting skills :P

Mooger5
Expert Member
Expert Member
Posts: 1422
Joined: Tue May 06, 2008 5:11 pm
Location: Lisbon

Re: Yamaha CS-50 All Keys of E not working

Post by Mooger5 » Wed Oct 03, 2018 9:27 pm

This was a fun thread! Too bad the OP never reported back. It would be good to known if all that talk helped to fix the synth.
Herrare umanum est.

meatball
Newbie
Newbie
Posts: 11
Joined: Wed Oct 03, 2018 5:09 pm

Re: Yamaha CS-50 All Keys of E not working

Post by meatball » Thu Oct 04, 2018 5:13 am

Mooger5 wrote:This was a fun thread! Too bad the OP never reported back. It would be good to known if all that talk helped to fix the synth.
yes i'd sure like to hear more about what went down etc

Post Reply