Yamaha CS80

Hi All,

Whether the FC7 pedal control is compatible with the CS80 is not
completely clear from what can be read here and there on the web.
I had a "shocking" experience with mine that I want to share.

I have a CS60 on which both FC3 and FC7 work OK. So I was rather
confident when I decided to plug the jacks of the two pedals in my newly
acquired CS80.
When I switched the CS80 on, a two seconds light "shhh" could be heard.
No smoke from the CS80, however.
A bit worried, I checked everything but there was no sign of the CS
being "wounded". So I dared to play a few notes : the CS80 was still
able to sing. (very deep sigh of relief then!)
The emotion being away, I decided to check the FC3 (pedal switch) and it
worked as expected. But with the FC7, nothing happened. Only when I
disassembled the FC7 did I realize how lucky I was.
The carbon track of the FC7's potentiometer was burnt. The carbon track
worked like a fuse.
Look here for the evidence : FC7 burnt potentiometer
<http://groups.yahoo.com/group/yamahacs80/photos/album/714107855/pic/152\
8156028/view>

Why some users apparently  don't have any problem with their FC7
connected to the CS80 whereas others do?
Can someone shed some light there?

Joachim



[Non-text portions of this message have been removed]

I have 2 FC7 pedals (none of which I have tried on my CS80)... the original pedal uses a lightbulb and photocell with a teardrop hole shaped shutter between the 2 elements. At the narrow end of the shutter, no light passes to the photo cell and as you move the pedal/shutter so  the round side of the teardrop is between the 2 elements, the photo cell receives full light and the circuit changes... there is a voltage in a cs80 that lights the bulb all the time whether it is low or high in position... there is the third connection which is the output of the photo cell... I had a misfortune about 12 years ago where my Optical pedal had a short inside the male 1/4 jack.... the short took out a ground rail inside my cs80 as a fuse.... you are lucky your pedal burned up..... retracing the burnt ground rails was close to a thousand dollars in the shop. remember... that jack has a voltage
being sent to power a bulb all the time... the optical coupler circuit should not be carrying voltage...
How people claim the FC7 pedal should work is not an option I would care to risk....

-----Original Message-----
From: joachim.milson <joachim.milson@...>
To: yamahacs80@yahoogroups.com
Date: 05/19/13 05:20
Subject: [POSSIBLE SPAM] [yamahacs80] FC7 pedal on CS80 : beware!

       
Hi All,

Whether the FC7 pedal control is compatible with the CS80 is not
completely clear from what can be read here and there on the web.
I had a "shocking" experience with mine that I want to share.

I have a CS60 on which both FC3 and FC7 work OK. So I was rather
confident when I decided to plug the jacks of the two pedals in my newly
acquired CS80.
When I switched the CS80 on, a two seconds light "shhh" could be heard.
No smoke from the CS80, however.
A bit worried, I checked everything but there was no sign of the CS
being "wounded". So I dared to play a few notes : the CS80 was still
able to sing. (very deep sigh of relief then!)
The emotion being away, I decided to check the FC3 (pedal switch) and it
worked as expected. But with the FC7, nothing happened. Only when I
disassembled the FC7 did I realize how lucky I was.
The carbon track of the FC7's potentiometer was burnt. The carbon track
worked like a fuse.
Look here for the evidence : FC7 burnt potentiometer
<http://groups.yahoo.com/group/yamahacs80/photos/album/714107855/pic/152\
8156028/view>

Why some users apparently don't have any problem with their FC7
connected to the CS80 whereas others do?
Can someone shed some light there?

Joachim

[Non-text portions of this message have been removed]









[Non-text portions of this message have been removed]

The mystery was solved this morning. As the title of this topic adds to the already great confusion about using an FC-7 pedal on the CS-80 EXP connector, I thought a conclusion would be useful.

Since April, I've been wondering why this did happen to my FC-7 pedal. Why did the carbon track of the potentiometer of my FC-7 burn while I tested it with the CS-80? I had no problem using it with a CS-60.

So I spent some time with the schematics. But the more I read them, the more I was convinced this should have never happened.

So last weekend, I decided to give a close look at the PRA board, the one where the three wires from the EXP pedal jack arrive. I removed the wires and used a potentiometer instead. I could hear no effect while turning the pot, though the voltages varied as expected. While removing the board from the rail, I had noticed two resistors soldered on its back. They were soldered in parallel to the output of the two photo-couplers used to control the left and right output levels. I removed them and abracadabra, the EXP and EXP-WAH were back again. Great! Now, why the heck did someone soldered these two resistors?

I removed the potentiometer and soldered back the three wires. The CS-80 was now as silent as a grave!
OK, it was now clear that either the three wires or the jack connector itself was guilty for this dark matter! I checked the wires and they proved OK. So there was no escape but rolling up my sleeves and ripping open the female jack connector. (By chance, this is feasible.) I disassemble the connector (if you ever wanted to know how it looks inside, look here: http://groups.yahoo.com/neo/groups/yamahacs80/photos/albums/1848204973)
and... oh, everything is now clear: the tip of a jack connector was trapped inside!
After reassembling all parts (the jack tip excepted, of course - I'm thinking of some kind of punishment for it), I tried the CS-80 with an other FC-7. And guess what? No shhhh, no burnt capacitor, no smoke whatever. It just works fine, both EXP and EXP-WAH.

The FC-7 pedal resistor is an ALPS 50k log. So the resistance value between tip and ring or ring and sleeve varies between 50k and about 500 ohms. And there is also a 2.2k resistor at the input of the PRA board, so the path is never short-circuited.

As a conclusion, before using an FC-7 pedal on a CS-80, check carefully the inside of the CS-80's EXP connector!