Yamaha CSY-1 Synthesizer problem

[Stingrayjay]

Hello, I would love to know how to repair this wonderful organ of mine. It was fine up until a few months ago and then it was moved from my parents to my home.

All functions work except for the synthesizer. As soon as I turn on the organ within a second and I press down a key to engage the synthesizer, I can hear it very faintly and then it fades out. I can't repeat that sound unless I turn it off and turn it on again and hold a key within that split second. The synthesizer switches work when manipulating the sound within that one brief second.

I have opened up the organ, but I really don't know what to look for. Would there be a certain fuse or capacitor that can be affected? The few bulb fuses are not blown. The organ is fairly clean inside considering its age.

Please let me know of any suggestions and I appreciate your time.

Thanks

[Stingrayjay]

I don't know how to fix it

[handyczech]

No one seems to be answering, and my knowledge is of mostly with the oldest Hammonds, but later totally electronic Hammonds probably have some similarities in their issues.

All organs of this era may have problems with dirty connections in the various plugs that connect the innards together, I would recommend that you got to ebay and try to find the service manual to get a feeling where internal components are that may relate to the function you are missing. Obtain a good contact cleaner spray like deoxit, and carefully remove connectors, clean them with deoxit, and then carefully reseat them. It is possible that this is a mechanical problem, especially since you say the organ was just moved. Don't be afraid to study the service manual even if you are not going to do in depth servicing. It will give you a better understanding of how the instrument works.

[Stingrayjay]

Thank you for your response. I see no reason not to start with your suggestions. It's unfortunate that the best part of the organ is not functioning. I'll update with my progress.

[Ronja]

Hiya. I have taken the solo synth out of a Yamaha CSY-2 to make a stand alone synt of it. I am not sure if there are alot of similarities between the two models, byt I recon there should be a few. One thing is that the solo synth has its own power supply, since it runs on +/- 15V dual rail. In my organ the supply was on the side wall on the right side when you open it from the back. Turn on power and measure if you have both rails going to start with, and we can take it from there.

Do you have a repair manual for it? It helps tremendeously when you can actually look up each function and trace eventual faults along the way.

[andyg]

You should start a new thread for this please, and place the request for a service manual in the correct section of the forum where it should get more views. Thanks

[Ronja]

Oh, I am sorry Andy. I was not making a request for the manual. I was asking the threadmaker if he had a repair manual for his CSY-1, since it had helped me alot with mine with on. My post is in regard to the original post and the eventual problem he would have with his organ. Since there might be alot of similarities between the two models I mentions where he could start looking for fail in his organ. English is not my native language. Perhaps some things were lost in translation? When I re-read my post I see how it can look like I am hijacking the tread. That was not the case this time though. :-D

Stingrayjay: What progress have you made so far?

[Stingrayjay]

Thanks Ronja for replying.

Here is my progress so far: Purchased deoxit and tried to clean up some of the connections. No change. Also, just ordered a service manual and should get it in a week.

If I touch the synthesizer volume solder and the circuitry for the synthesizer sounds I get audio and can manipulate the sound with the keys. However I barely get any sound when just pressing the keys normally.

The two rails the synthesizer boards sit on, top rail is at 15v and the lower rail is at 0. Is that normal?

[Ronja]

What is the name of the IC's on the power supply? It might be that the CSY-1 has a different power supply, but I doubt that since the actual solo synth section should be almost identical betweenn the two models (I read/heard this somewhere, but I cannot find the source at the time of writing). The rails should be +/- 15 V with 0 ground in the middle. On the CSY-2 the power supply has two Sanyo STK-502 IC's to regulate the power. There is a brown wire for the 15 V, Black for ground and yellow for -15 V. When I measure between the brown and yellow I get 30 V, between brown and black 15 V and between yellow and black (make sure that the common (usually black) tester is on earth) -15 V. If you measure with the 'red' tester on earth and the 'black' on the -15 V the meter will show 15 V.

It is confusing when things have the same name. The rail I am talking about is the power rail, which in this case is not a physical rail in that sence since the cables come directly of the power supply board. When speaking of single/dual rail in power supply single means you have (usually) a positive power and ground. When it is a dual rail it is a positive, a negative and a zero potentional, where the zero potentional is usually referred to ground/earth. In this case we have 15 V as positive, -15 V as negative. The can be other values depending on the circuitry, but in the CSY-synths there is +/- 15 V.

It should be easier to do fail-search when you have the repair manual and can see what voltages you should expect and where. The layouts make it so much easier, aswell as getting the color-coding in plain writing.

If the -15 V rail is not working as it should I am not sure as what would work or not and how.

I was startled when I read you get a 15 V potentional between the metallic rails. But when I measure on mine I actually get it too! It seems the 15 V connection on some cards come in contact with it. If that's the way it should be or not is another question. I mean; it works as it it should. I have not read anywhere that it is supposed to be like that though...
If you look at the cards; are there a brown wire coming into the cards very close to the rail? Is there a marking saying "+ 15 V" at it?

As for the soundproblem; sounds like there is an intermittent connection somewhere involving ground. That could have gotten worse when the organ was moved. Pure speculation on my part though.

[Ronja]

While looking at the diagrams for the Yamaha DK40A it is quite visible that they used the metallic rails aslo for the earth and voltage. Very strange for me, since all kinds of interferrence and possible shorts can be imagined...

I know not too many ppl will see this question here, but is it common practice among other manufacturers to actually distribute power that way too (there are cables too, so it is not exclusively the metallic rails that do it)?

[Stingrayjay]

As you can see, I am very new to this repair work, hence my confusion of the rails. Thank you for the clarification. There is a +15v voltage right at the top of one of the cards, but it isn't making direct contact to the metallic rail and it still produces the 15v. However, I guess it is normal in comparison to yours.

It appears that we do have the same power supply. I also tested the four wires( brown, yellow ×2, black) and they have the correct voltage according to your response. Based on my many, many, many, hours of inspection.. I also feel that a ground is loose. With the service manual coming, I will go through everything and test its voltage and look to where all the grounds are.

Since I am actually able to get a synthesizer sound from touching some of the contacts at a same time, it is promising that it may be a power issue.