Keybed repair/restoration?

[AVaughn]

I have a 1-manual 1970 transistor organ (GDR) with a less than perfect action. The reason for this is poor shipping. When it arrived, many notes wouldn't press as the keyframe was bent. I had the keyframe/keybed "straightened out", so that all keys are more or less aligned, not jagged, all notes do work fully, and create sound, but here's the issue.

For every note, there are 5 strings that make contact with 5 metal bars when you press a note, and on many notes, the strings don't make contact simultaneously, giving a staggered effect where the registers don't all play at once. The further (deeper) you press the note, the more of the harmonics make contact. If you play powerfully, you can almost get rid of this issue, but that is no solution.

Are there people that work on keybeds? People that take them apart, calibrate them, refurbish them, for optimal performance? Or.. are there people that could, for a price, make a custom keybed to replace the one I have to the exact specifications? As I feel quite strongly I won't find a spare.

Alternatively: is there anything a 20 y/o with plenty of free time and perseverance, albeit hardly any technical experience (besides A-level physics) or any kit (but the means to buy any), can do? I have already decided on learning to solder, and to get an oscilloscope, and other circuitry checking tools (I have been refused service by a number of organ restoration companies based in the UK on account of circuitry), but the keybed just seems like a totally different beast to tackle.

I have the original service manual, which will give me the ability to make sure that all tone generators are in tip top condition (although they do work almost perfectly as things are, but components are abundant as they are soviet), and as I work through translating it, I will see what is written about the keybed, but until I get to that, I am to seek advice from the internet.

I can provide any pictures that are requested. Any general comments, life experience, advice, would be hugely appreciated.

[jbird604]

I'd suggest that you just keep doing what you're doing. Figure out how it works, what is causing it to work poorly, and find a way to fix it. The staggered closing of the switches might not actually be caused by misalignment though. It could be that the switches themselves need cleaning or burnishing, and are not making good enough contact to pass the signal until some tension is applied. Try fixing just one note at a time and making it work properly, then you'll know what to do with the rest of them.

You don't have much to lose, working on something of that age. Anything you do to improve it will be a positive. What you have plenty of -- time -- is the most important factor in fixing something like this. When we are working on a modern organ, we usually try to get the job done as quickly as possible, and that is usually possible because modern stuff mostly just needs a board swapped or a minor adjustment. But working on vintage instruments, you need a lot of time and you need to be willing to try different things until you figure out how to make it work.

Good luck!

[AVaughn]

I appreciate the kind words, that is exactly what I am going to do.

I see that you are a moderator, I hope it's ok with you if I leave this thread open. It's possible that another member of the forum has something to say.

[myorgan]

John is also on "the other side of the pond," so his advice is only good for North America (just kidding). Welcome to the Forum, and I'm sure you've discovered it doesn't take long to find good advice you can use.

Best of luck with your keyboard restoration project. It is certainly frustrating when a delivery service nearly destroys your product. I had that happen with a printer once and had to send it back.

Again, welcome to the Forum!

Michael

[jbird604]

Yes, sadly I can't even get across the pond right now! If not for this danged virus, we'd be strolling the streets of York today and attending Evensong about 5:00 p.m. But once we are finally able to get there, we'll enjoy it all the more!

[myorgan]

Where is Andyg on this thread? I would think he could help.

Michael

[AVaughn]

To anybody still monitoring this... Since starting the thread, I have been able to further analyse the keybed. All keys taken off, some keys had broken plastic components meaning they wouldn't spring back up, someone had attempted to fix this by adding quite crudely another type of spring onto those broken keys. A respectable attempt likely since the broken plastic "components", you probably wouldn't find spares for those. So these "fix" springs were rubbing up against each other and messing up the action, but this couldn't account for the issue I have outlined in the start of the thread, potentially just added to it.

I'm probably going to look for some 3D design expert and send one non-broken piece to them to make a 3D model. Then i'll have to have someone with a 3D printer make copies of these plastic parts, my primary concern is durability (of course there will be cycles and stages of testing, before I order ~20, testing different types of plastic). These components are also the ones that hold the 5 "contacts" for each key, so very important that they are present, accurately replicated, and working. (Are there plastics people that do small-scale things like this? Soliciting independent randoms on the internet, the website fiverr, for example, it's all that I can think of really.) Having taken out all 5 octaves, these components are the last thing between me and good access to the contacts.

The plan for these contacts is to use some anti-oxidant, anti-corrosion stuff, but I don't want to add to the layers of (now) gunk that has been sprayed over the years onto these contacts and what's below them. So I will possibly be wiping/cleaning each contact manually with a damp cloth unless their fragility doesn't allow for that. No contacts appear damaged, broken, or missing. I'd be worried replacing contacts, so I really do want to clean them up. If there are any techniques for doing this safely, I'd like to know.

I appreciate that this stuff isn't all to informative without pictures, but potentially someone with this exact organ could follow along.

My inspiration has been:
http://www.theamericannight.com/voxproject/project.html [If my skill allows me, I'd like to replicate this, re-tolexing and all. After all my organ is also with germanium components]
https://eigenbaukombinat.de/reparatu...ansistororgel/ [a simple component repair on a very nice unit of the same model as mine] After reading this, I confirmed that indeed, any components I need are likely going to be very easy to find on the russian internet (I speak russian).

Not even close to working with circuitry yet... that is going to be the scary part, with the steep learning curve. When I do, I'll have to use lead-based solder as that's likely what was originally used, and hopefully my ventilation is good, as apparently that's toxic.

[AVaughn]

Thanks for the heads up Michael. I did happen to notice this when I took all the keys off. The component I am referring to is actually one that attaches to the underside of each black and white key (the one that makes the contacts work), and that component is identical all through the keyboard. I appreciate that I have not been writing things clearly.., But comments like that are always welcomed by me!

[Larrytow]

You said you were thinking of cleaning the contacts with a "damp cloth". If you mean dampened with water, Don't Do That. Alcohol on a Q Tip ( cotton swab ) is the way to go. Best to use is Isopropyl Alcohol, 91%. But I have used plain old denatured alcohol for painting use with good results too. Now and then you can get contacts that are gunked up enough that you may have to resort to using Acetone to get them clean. Once they are clean, you can use contact cleaner / preservative on them.

[AVaughn]

Thanks Larrytow for the comment. Unfortunately, even with components removed, my access to the contacts is limited, so Q-tip it is... The "gunk" or whatever that's on the contacts makes large parts of the contacts appear black/grey/grown, and it's not really sticking out, or gunky in any sense of the word. Acetone is something I hadn't thought of before, and I think after some research I'll be getting some, as alcohol based stuff isn't getting me very far.

[AVaughn]

Thanks to everybody for the advice and support in this thread. Some annotated pictures that I made, are coming later today if I don't forget!

[myorgan]

At various times people have recommended cleaning contact oxidation with a certain percentage of Isopropyl Alcohol. At the same time others advise not using any water in cleaning contacts. Isn't the remaining percentage of Isopropyl Alcohol mixture-water?

Curious minds and all.

Michael

[AVaughn]

Ok, so I have returned with some visuals to go along with the text. All of these pictures are ordered and annotated, and hosted on imgur HERE (https://imgur.com/a/XBR8gCA)

Picture 1 shows the keybed in It's current state. I have taken all of the springs off the keys, and then removed all of the keys. I have made a start on taking out the plastic components responsible for contact containment and movement (the lowest octave, and some keys at the top have been removed by me, also each of the C keys apart from the top one are colored blue).

Picture 2 shows a portion the removed keys, and picture 3 shows the springs that go along with them.

Picture 4 is a picture of non-broken contact holders, taken out of the keybed safely, and picture 5 shows an underside of one of the keys. Hopefully you can see how the two are supposed to connect.

The first thing I noticed is that some contact holders had springs attached (picture 6). They are supposed to pop up when a key is released, but about 10 of them were broken so that they would no longer move in unison with the keys, the springs are a “fix” for this. Here's the corresponding picture (picture 7) showing *how* the contacts are broken. Picture 8 shows some of these broken tops, which I found inside the organ loosely.

These parts are the parts I am looking to have 3d printed, if that is a solution rigorous enough to provide working pieces. It may be the case that 3D printed plastics are simply not up to scratch for whatever reason, but nonetheless this will be my first route.

Next: regarding the contacts themselves. I believe that many are covered in some sort of layer of something, which has over time caused decreased performance (ie, the contacts must make firmer than normal contact with the rod in order to produce sound). As it's not standard gunk, and my access to them is limited, I was puzzled on how I could clean them.

Picture 9 is a close up of the contacts. I photographed this section for the reason that you can clearly see, the 4 contacts at the front are a different colour to the contact at the back. The contact at the back appears metal coloured, and seems mostly unaffected by whatever spray/corrosion affected the other contacts.

As a test, I took a cotton bud soaked in alcohol and attempted cleaning a section of a contact I had access to, lo and behold, I was able to make part of a dirty contact appear silver again.

So my idea is not to clean the entire surface area of the contacts, but only the part that is supposed to make contact with the rod responsible for conductivity.

Problem is, that gap is so small you can't even fit a pin in there, let alone a cotton bud. So I need to take out the 5 rods which appear pointed at the end, this will allow me to bend the contacts back slightly, giving me access to the portion between the contact and the conductivity rod. These pointed rods serve no electrical purpose to my knowledge, and are just there to help hold the contacts in place. They should slide out of the keybed without much issue, however on the other end, they are soldered to a wire which attaches onto some plastic, serving the purpose of holding it.

So, this early in the process of the restoration, I already need a soldering iron, despite not having the intention (yet) of working with the circuitry.

Picture 10 shows how it's not feasible to actually remove the contacts for cleaning.

To anyone that was struggling to picture what I was saying, hopefully this helps.