Yamaha YC-45d volume pedal cut off, blowing fuses.

[soundsubs]

Hello Group!
I found a Yamaha YC-45d in a pawn shop for $200. Didn't even try it out, just bought it and hauled it home.
Immediately found that the volume footpedal had been cut off with scissors and discarded. I stripped the wire shields and shorted the red and white wires together and voila! Working again!
It worked for about 2 weeks this way. No issues that I could tell, but the solution wasn't pretty.
Then I decided to make this more permanent, so I soldered the two wires together and stuffed the cable back up inside the foot pedal holder.

Somehow in the process of this, it blew the main 250v 1A fuse. I replaced the fuse-- which was soldered in, and on power on it blows it immediately. I've tried this three times.

Any ideas? Sounds to me like a power supply problem, but surely someone here has experience in this.

thanks in advance!

[joecool240]

I don't know how proficient you are with electronics and reading schematics, but below is a link to a YC-45D service manual.

http://manuals.fdiskc.com/flat/Yamah...e%20Manual.pdf

First thing I would do is "un-do" everything you did and see if the fuse still blows.
Carefully separate all the wires that were cut and be sure nothing is shorting to another wire or chassis metal.
That might be easier than discretely troubleshooting the power supply.

Note that on this organ, a DC voltage goes to the expression pedal for the photocell lamp.
If this voltage got shorted, that could be blowing the fuse.

Joe

[soundsubs]

Excellent idea, thank you.

I've already downloaded the service manual and I'm going through it.

Wondering if anyone has permanently disconnected the volume pedal and what those steps might be.

[joecool240]

To bypass the expression pedal, simply connect the center conductor of the shielded red wire to the center conductor of the shielded white wire.
See page 44 of the service manual for the expression pedal circuit.

There are two blue wires that carry the DC voltage to the expression pedal lamp . . . be sure these two wires are not touching anything.
Cut them flush and tape or heat shrink the ends.

You may have to turn down the master volume with the expression pedal bypassed, as without the expression pedal resistance, the organ's output will probably
be louder than when the expression pedal was attached.

Joe

[soundsubs]

Again, Joe, thanks.

I'm thinking of cutting it off at the posts inside behind the keys. That way there's no accidents waiting to happen.
So i'll cut the two blue wires of their posts, and connect the Red and White posts.
Make sense?

[joecool240]

Sounds like a good plan.

Just be sure the organ's AC power cord is unplugged from the wall socket when working inside the organ.
There is exposed AC power on the power supply chassis even when the organ if turned off.

Joe

[soundsubs]

The fuse blowing continues! I'm making ACE Hardware rich, $4.95 at a time!

1.) I cut the food pedal cable off, leaving a RED, White, two blues, and two shields unconnected. Then I cut off the two blue wires. Tried a new fuse. Blew it upon power up.
2.) I cut the exposed shielded braids off of the power posts and the 1/4" jack. Soldered in a new fuse, and blew it on power up.

Now it stands like this:


...with only the red and white posts connected at the posts.
At their far end (the cable is now about 6") the Red and White are not touching.

(thanks again for helping here)

[joecool240]

At this point, you need to isolate if the problem is in the power supply, or elsewhere in the organ's electronics.
I would disconnect the organ's electronics from the power supply as follows:

Referencing the power supply board diagram (Page 46), disconnect from the power supply board the PK12 (+2) wire, the BL12 (E) wire, the RE12 (-12) and the GY12 (-26) wire.
With these wires disconnected, if the fuse still blows, the problem is in the power supply.

Joe

[soundsubs]

Excellent point. I will do so ASAP.
I had a thought: is it possible that something is wrong in the Voltage selector underneath?
It is currently set to 117V, and I'm wondering if it is all passive electronics in that jumper?

[joecool240]

Voltage selector is simply a jumper, it's all passive.

[umma gumma]

I don't know how proficient you are with electronics and reading schematics, but below is a link to a YC-45D service manual.

http://manuals.fdiskc.com/flat/Yamah...e%20Manual.pdf

First thing I would do is "un-do" everything you did and see if the fuse still blows.
Carefully separate all the wires that were cut and be sure nothing is shorting to another wire or chassis metal.
That might be easier than discretely troubleshooting the power supply.

Note that on this organ, a DC voltage goes to the expression pedal for the photocell lamp.
If this voltage got shorted, that could be blowing the fuse.

Joe

Hey I just wanted to say thanks for posting that link, I have a YC45D with vol/expression pedal issues I am trying to sort out as well

service manual will be very useful

[umma gumma]

replaced the bulb ( 24v ) and it appears to be working fine now.

it was a pain to pull the whole pedal apart, to get to the bulb!

too bad it's not easier to get to the bulb: I wish it was just 4 screws on the bottom, like a wah pedal

( surprised there are no instructions in the service manual for changing it )