Yamaha DSC-20M Digital Stereo Chorus

[DJGlukBH]

Hi all, my first topic here
I've got the Yamaha DSC-20M digital stereo chorus for repair. Pedal's overall condition is good, nothing seems to be touched by the previous owner. But the chorusing sound is a bit distorted on big depth values so I'm thinking about replacing the old electrolytic caps. Posting some guts pics below since I haven't found anything about this pedal.
If anyone has a service manual - please PM me. I have the oscilloscope and wave generator to get this pedal checked and recalibrated.
Any ideas about the repair, advices are appreciated.

yamaha dsc-20m-2

yamaha dsc-20m-1

[DJGlukBH]

Nevermind... The pedal was fixed by adjusting a small calibration trimpot on the slave pot pcb.

[ilcaccillo]

Hi,
nice to see your thread and Im happy you were able to fix your pedal.

I'm in the process of repairing my pedal also, it's hard because I have not schematic and there's not much info on the web on this model also.

Could you please help me with some pics?
Do you have more pictures of the guts of your pedal?

It would be a huge help if you could some more pictures of the insides of your pedal, specially the connections from the pcb to the Out B jack.

thank you

[ilcaccillo]

Hello,
I'm fixing an Yamaha DSC-20M chorus pedal,
the pedal came to me without any jacks at all.

I was able to install replacement jakcs for input and output altough I'm having problems with the connections for Out B.

I don't know which wire connected to where on Out B, also cant find a schematic for this pedal.

If there's any member that owns this pedal could you please take a picture of the Out B jack wiring so I can fix this pedal?

Schematic or a description of wire colors and where they connect to tOut B would also be good, but just the picture would be more than enough.

Thank you so much

TGS

[ilcaccillo]

Hello If you have a schematic for the Yamaha DSC-20M or can take some inside pics of PCB and wiring that would be great.

Thank you so much

[ilcaccillo]

Please if you have this unit,
take some pics of the Out B Jack and wiring from that jack to the main pcb.

Thank you

[Dirk_Hendrik]

I have none of what you're asking.

But a series of photo's of your unit (sharp, no flash but using daylioght, details as well as overview) might result in an answer a lot faster than hoping that someone a) owns this puppy and b) is willing to spend time opening it up and posting pics.

[ilcaccillo]

I have none of what you're asking.

But a series of photo's of your unit (sharp, no flash but using daylioght, details as well as overview) might result in an answer a lot faster than hoping that someone a) owns this puppy and b) is willing to spend time opening it up and posting pics.

Thanks Dirk,
if this pedal was simple you would be right.
Although the circuit is quite complex so it might not be that easy.

Saying that, I will follow your advise and post pics.

Thank you

[Ice-9]

I have none of what you're asking.

But a series of photo's of your unit (sharp, no flash but using daylioght, details as well as overview) might result in an answer a lot faster than hoping that someone a) owns this puppy and b) is willing to spend time opening it up and posting pics.

Thanks Dirk,
if this pedal was simple you would be right.
Although the circuit is quite complex so it might not be that easy.

Saying that, I will follow your advise and post pics.

Thank you

I would have thought a few pics was the way o go, if you are looking for wiring of the jack and stuf then a lot of intelligent people here can make something of the pictures you take and post, without pictures to give anyone a clue , then I would say you will get next to no information back.
Pictures = help

[Cub]

Celedonia Organ Service has an original service manual for sale.
http://celedoniaorgan.netfirms.com/cos2 ... ts_id=1533

[ilcaccillo]

Celedonia Organ Service has an original service manual for sale.
http://celedoniaorgan.netfirms.com/cos2 ... ts_id=1533

Thank you I will check that

[ilcaccillo]

I have none of what you're asking.

But a series of photo's of your unit (sharp, no flash but using daylioght, details as well as overview) might result in an answer a lot faster than hoping that someone a) owns this puppy and b) is willing to spend time opening it up and posting pics.

Thanks Dirk,
if this pedal was simple you would be right.
Although the circuit is quite complex so it might not be that easy.

Saying that, I will follow your advise and post pics.

Thank you

I would have thought a few pics was the way o go, if you are looking for wiring of the jack and stuf then a lot of intelligent people here can make something of the pictures you take and post, without pictures to give anyone a clue , then I would say you will get next to no information back.
Pictures = help

I have done what you suggested in other threads here and unfortunately there was no help also, so I think the lack of help may have reasons deeper than that.

if you see this thread, I have pics, I detailed all the info needed, it's a really basic circuit , nothing like the yamaha DSC-20M, probably it's a Diode or a capacitor missing, There's 609 views and zero help, check it out:

https://www.freestompboxes.org/viewtopic.php?f=7&t=27386


In the different DIY forums were I'm active I try to be as helpful as I can, so when I can take inside pics of units I have by people request or needs I would do so in order to help a fellow member so I really can't see why do you find strange for me to ask a simple photo of the original wiring of a Jack, because in reality just that pic would be enough to solve my issue.

Saying this, yes of course, I can and will post pictures as you've suggested, I just don't have the pedal with me at the moment, but will do asap and post the pictures here.
what will happen next is that there will be zero help, and then I will fix the pedal one day when I can get an inside photo or When I buy another DSC-20M just to see the guts and fix my unit.

[Dirk_Hendrik]

Please don't post those pics.

If your assumption is "there will be no help" better refrain from asking. I mean, what do you expect if your attitude is like this?

[Ice-9]

I have none of what you're asking.

But a series of photo's of your unit (sharp, no flash but using daylioght, details as well as overview) might result in an answer a lot faster than hoping that someone a) owns this puppy and b) is willing to spend time opening it up and posting pics.

Thanks Dirk,
if this pedal was simple you would be right.
Although the circuit is quite complex so it might not be that easy.

Saying that, I will follow your advise and post pics.

Thank you

I would have thought a few pics was the way o go, if you are looking for wiring of the jack and stuf then a lot of intelligent people here can make something of the pictures you take and post, without pictures to give anyone a clue , then I would say you will get next to no information back.
Pictures = help

I have done what you suggested in other threads here and unfortunately there was no help also, so I think the lack of help may have reasons deeper than that.

if you see this thread, I have pics, I detailed all the info needed, it's a really basic circuit , nothing like the yamaha DSC-20M, probably it's a Diode or a capacitor missing, There's 609 views and zero help, check it out:

https://www.freestompboxes.org/viewtopic.php?f=7&t=27386


In the different DIY forums were I'm active I try to be as helpful as I can, so when I can take inside pics of units I have by people request or needs I would do so in order to help a fellow member so I really can't see why do you find strange for me to ask a simple photo of the original wiring of a Jack, because in reality just that pic would be enough to solve my issue.

Saying this, yes of course, I can and will post pictures as you've suggested, I just don't have the pedal with me at the moment, but will do asap and post the pictures here.
what will happen next is that there will be zero help, and then I will fix the pedal one day when I can get an inside photo or When I buy another DSC-20M just to see the guts and fix my unit.

Hi, I'm sorry you feel that way, I am also sure you will find this a hugely friendly and helpful forum if you stick around, sometimes people don't reply to a post if they have nothing to contribute to it. .

As for the pictures, the reason I asked for pictures of the pedal you are trying to fix is, firstly I don't have a Yamaha DSC20M to take a picture of for you and secondly none of us would know what has been changed, or bodged on YOUR pedal without a picture. If none of us here have ever owned or repaired that model of pedal a simple high quality picture would be invaluable in helping you.

Also as far as replying goes , just like the rest of the forum members I may not sit at my pc 24 hours a day so it may be a few days before I even see your reply so a little patience is needed on your behalf.

I have just had a look at your picture on the other thread you have pointed too and the quality of picture is not very good, but I got the point of the person who replied about removing the solder/flux mess from the PCB. Stuff called pcb cleaner is available but I have never seen a circuit that acetone does not remove flux, the stuff on the pedal you have shown is an epoxy resin (goop) put on to stop people trying to copy the circuit, it looks like the damage is from trying to remove that stuff. so unless you have the skills to trace that pedal and fill in the blancs from the damage then I would give up on that one. or find a schematic already published.

regarding the Yamaha, Without sounding rude, if you don't supply the information 'WE' need to help 'YOU' then your wasting your time.

[Ice-9]

I have just done a 20 second google search, found this page with some pictures, a simple pedal, some jacks are pcb mounted .

http://blog.livedoor.jp/solidstation/ar ... 31822.html
does it help

[ilcaccillo]

Hi,
there was no bad attitude on my part, but I'm sure my words were misinterpreted.
The reason for no replies is because this is a guitar pedals forum. Guitar pedals are normally simple and basic electronic circuits, most of of the forum members will be guitarists completely new to electronics trying to do some pedals for fun. So it's not that people don't want to help, it's because most can't really help because they don't have the knowledge to do so.
Thats what I meant in saying that the reasons for no help was not because I was not posting a picture but was actually "deeper than that"
For the rest of forum members, the ones that are really knowledgeable 2 things happen, or they are bombard a lot with all the less experienced members asking for help or they are respectfully working on their own projects. Point is obviously they don't have the time for all the needs around here, it's understandable.
That's why I didn't get 1 reply at all in a thread about a missing component, can only be a capacitor or a diode, in the most basic circuit there is for a guitar pedal, a transistor booster.

Because of this I still feel that a picture of the Out B jack wiring from a working unit would be and still is the best option, if any member of this forum as one of this units, and is helpful enough to take the 4 screws and take 2 to 3 pics with the phone. It takes 1 minute, and Im pretty sure in so many people in this forum there will be someone that has this pedal in their collection.

That is much easier than expecting and experienced forum member to chime in, having to understand a complex digital circuit from pictures without schematics,
beware this is not an overdrive project, the circuit is not an overdrive.

I have just had a look at your picture on the other thread you have pointed too and the quality of picture is not very good

Sorry, But you're wrong the pictures are very good.
The pictures are there to show the spot of the missing component and they perfectly represent that.
I explained everything in the thread.

I have never seen a circuit that acetone does not remove flux

As I told in the thread, I dont know if this is flux or whatever it is, but Acetone doesn't remove it.

it looks like the damage is from trying to remove that stuff

No it's not, did you read the thread?
As I explained the damage is from a burned component, probably it was a diode and probably it was because of an higher voltage or wrong polarity used. My doubt is if there was a capacitor also parallel to that diode

so unless you have the skills to trace that pedal and fill in the blancs from the damage then I would give up on that one. or find a schematic already published.

There's no schematics already published for this Revision of the Fatboost.
Yes I have the skills to trace the circuit, told that in the relevant thread, what I still dont know is how to take that gunk/cement out without damaging traces on the PCB.

But even if I couldn't trace it there a way that anyone could really fix it, even a newbie, it would be if a forum member with the same pedal posted a picture of the guts of his working pedal.
Or following your advise, by putting my pedals pictures then " a lot of intelligent people here can make something of the pictures you take and post", but no one really posted. And even you that suggested this option looked to my basic/boost pedal circuit, 1 component missing and you say "I would give up on that one" LOLOL really? thats not really coherent.

As you see I did this thread in the "Requests" section of the forum,
it's a place that is dedicated to ask something like a "Schematic or guts shots for Repair"

And I will still would like to ask this,
Please if theres a forum member that owns an Yamaha DSC-20M Chorus pedal it would be really helpful if you could take some pics of the OutB jack wiring.
Thanks you so much

If someone has or encounters a Schematic for this pedal, that would be great also.

[ilcaccillo]

I have just done a 20 second google search, found this page with some pictures, a simple pedal, some jacks are pcb mounted .

http://blog.livedoor.jp/solidstation/ar ... 31822.html
does it help

Do you call a guitar pedal with 14 IC's a simple pedal?

Thanks for the pics, I also have those but the picture I need is for the OUT B jack wiring,
it's an open jack that screws to the top of the case, and some wires that connect to the main circuit pcb.

Please if you have this unit,
take some pics of the Out B Jack and wiring from that jack to the main pcb.

Thank you

[Dirk_Hendrik]

Do you call a guitar pedal with 14 IC's a simple pedal?

Thanks for the pics, I also have those but the picture I need is for the OUT B jack wiring,

Yes, I do call a 14 IC pedal simple if it concerns your problem. Most of these IC's have nothing to do with your problem so they don't count. Furthermore I only count 8.

Then.
Your pedal has one working and connected output. It's on the PCB. Now, I'm willing to bet that the output stage (opamp or transistor, most likely followed by a cap and a resistor, terminated with a resistor to ground) for the other output is exactly the same. Difference is it goes to a wire connection point instead of a jack. Find that output stage and fix your pedal. And even better, all connections seem to be made on connectors. How hard can it be finding the right one?

[Ice-9]

Do you call a guitar pedal with 14 IC's a simple pedal?

Thanks for the pics, I also have those but the picture I need is for the OUT B jack wiring,

Yes, I do call a 14 IC pedal simple if it concerns your problem. Most of these IC's have nothing to do with your problem so they don't count. Furthermore I only count 8.

Then.
Your pedal has one working and connected output. It's on the PCB. Now, I'm willing to bet that the output stage (opamp or transistor, most likely followed by a cap and a resistor, terminated with a resistor to ground) for the other output is exactly the same. Difference is it goes to a wire connection point instead of a jack. Find that output stage and fix your pedal. And even better, all connections seem to be made on connectors. How hard can it be finding the right one?

Yes as said above only 8 IC's those other things you think are IC's are in fact resistors.

From the pictures I sent you a link for, I can see what looks like the front panel output jack just in shot, wires that look like they come from that go to a little 3 pin header which is coloured orange and is right next to the board mounted jack , so with an educated guess that is your answer. But you have the full pedal to confirm this not me, which is a simple task for you to check

[ilcaccillo]

Do you call a guitar pedal with 14 IC's a simple pedal?

Thanks for the pics, I also have those but the picture I need is for the OUT B jack wiring,

Yes, I do call a 14 IC pedal simple if it concerns your problem. Most of these IC's have nothing to do with your problem so they don't count. Furthermore I only count 8.

Then.
Your pedal has one working and connected output. It's on the PCB. Now, I'm willing to bet that the output stage (opamp or transistor, most likely followed by a cap and a resistor, terminated with a resistor to ground) for the other output is exactly the same. Difference is it goes to a wire connection point instead of a jack. Find that output stage and fix your pedal. And even better, all connections seem to be made on connectors. How hard can it be finding the right one?

Yes as said above only 8 IC's those other things you think are IC's are in fact resistors.


From the pictures I sent you a link for, I can see what looks like the front panel output jack just in shot, wires that look like they come from that go to a little 3 pin header which is coloured orange and is right next to the board mounted jack , so with an educated guess that is your answer. But you have the full pedal to confirm this not me, which is a simple task for you to check

Yes you're right from the pictures it's 8 IC's still not a simple circuit for a guitar pedal.

As I already told you I had those pictures before, and I've seen that little bit of the front panel Out B jack. The connections to the jack are not on the orange pin header and the only wire that you can see in that really connects to the jack is the black wire so unfortunately that picture has no use at all.

Thanks anyway Ice-9, I'm sure someone will be nice enough to take a picture of the jack and send it, then it will be really easy to fix.

best regards