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Author Topic: Old GDR box - stuck button  (Read 1566 times)

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Fred

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Old GDR box - stuck button
« on: November 28, 2018, 12:11:29 PM »

I may have bought another box. Lovely condition, very little to change on it (it's in tune, great waxing, complete valves in good condition, has nice casework, etc.).

However, there's a little problem with it. The third button on the outer row is a bit stiff and gets stuck easily when pushed softly. But it springs back into position when pressed with a bit more "bounce", e.g. while playing.

I suspect it might be the spring that gets stuck on a wood splinter. The fingerboard is closed however, so I can't see or repair the spring of the button in question. See attached pictures for more info.

So my question is simple: How could I repair it? As always, I'm thankful for any tips or ideas. (:)
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Fred

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Re: Old GDR box - stuck button
« Reply #1 on: November 28, 2018, 12:12:58 PM »

Another pic
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Fred

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Re: Old GDR box - stuck button
« Reply #2 on: November 28, 2018, 12:14:17 PM »

Another pic
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Theo

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Re: Old GDR box - stuck button
« Reply #3 on: November 28, 2018, 12:20:11 PM »

The keyboard is horrible to work on on these GDR boxes.  As you have found there is no access to springs, and if you try to withdraw the axle rod that is problematic too.  It is usually very tight, its rather thin brass and if you manage to get it out without breaking it you deserve a medal.  Once out you can only remove the individual lever after breaking off it's button.  If you manage all that you will find that getting the axle rod back in is even more difficult than getting it out, replacing it with a steel rod of the same diameter is more likely to be successful.   

If you don't fancy doing all that then it is possible to to replace a spring by keyhole surgery by cutting into the back of the keyboard,  it's less risky, but still a pain in the neck.

It's one of the very small number of jobs that I politely decline to take on.
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Theo Gibb - Gateshead UK

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Pete Dunk

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Re: Old GDR box - stuck button
« Reply #4 on: November 28, 2018, 12:58:13 PM »

In picture 1 the lever arms (for want of a better description can seen coming through a slot in the edge of the fingerboard. If the third key is slightly tight in the slot the spring may not be able to overcome the friction between the slot and the arm without the aid of velocity. Would it be worth trying to work a dry lube down either side of the arm (spray can used to lubricate plastic curtain rails etc) or mixing some graphite powder with meths as a carrier and apply with a small artist's paintbrush?
« Last Edit: November 28, 2018, 01:02:04 PM by Pete Dunk »
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JD

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Re: Old GDR box - stuck button
« Reply #5 on: November 28, 2018, 01:08:01 PM »

Another possibility is that the pallet for that button moves sideways slightly and drops back on to the adjacent pallet. It doesn't have to overlap by much to make it stick open and it will close if you make it snap shut. I have seen this on a Club box where the leather facing material wasn't trimmed quite enough.
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mselic

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Re: Old GDR box - stuck button
« Reply #6 on: November 28, 2018, 01:12:46 PM »

The keyboard is horrible to work on on these GDR boxes.  As you have found there is no access to springs, and if you try to withdraw the axle rod that is problematic too.  It is usually very tight, its rather thin brass and if you manage to get it out without breaking it you deserve a medal.  Once out you can only remove the individual lever after breaking off it's button.  If you manage all that you will find that getting the axle rod back in is even more difficult than getting it out, replacing it with a steel rod of the same diameter is more likely to be successful.   

If you don't fancy doing all that then it is possible to to replace a spring by keyhole surgery by cutting into the back of the keyboard,  it's less risky, but still a pain in the neck.

It's one of the very small number of jobs that I politely decline to take on.

This is exactly the same make of box that I worked on a few days ago, and I came to the same conclusions as Theo. I ended up informing the client that I couldn’t improve the action of the few sluggish buttons without potentially damaging the box, and I wasn’t willing to do that. If you do attempt to remove the axle rod, don’t be tempted to tap it out from the other end when it won’t budge - the channel for the rod is actually open along the length of  one end and, as Theo says, the rod is made of a rather flimsy brass and it would most likely bend.
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mselic

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Re: Old GDR box - stuck button
« Reply #7 on: November 28, 2018, 01:14:58 PM »

Another possibility is that the pallet for that button moves sideways slightly and drops back on to the adjacent pallet. It doesn't have to overlap by much to make it stick open and it will close if you make it snap shut. I have seen this on a Club box where the leather facing material wasn't trimmed quite enough.

This was also the case with the one I worked on, and I managed to bend the various pallet arms such that they could open and close without catching on each other. Kind of like an old typewriter...
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Dick Rees

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Re: Old GDR box - stuck button
« Reply #8 on: November 28, 2018, 01:15:53 PM »

In picture 1 the lever arms (for want of a better description can seen coming through a slot in the edge of the fingerboard. If the third key is slightly tight in the slot the spring may not be able to overcome the friction between the slot and the arm without the aid of velocity. Would it be worth trying to work a dry lube down either side of the arm (spray can used to lubricate plastic curtain rails etc) or mixing some graphite powder with meths as a carrier and apply with a small artist's paintbrush?

Yes.  Decent chance of success, little chance of harm.  Perhaps a pre-treatment session with a hair dryer to abate any swelling from humidity?


« Last Edit: November 28, 2018, 02:01:26 PM by Dick Rees »
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bellowpin

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Re: Old GDR box - stuck button
« Reply #9 on: November 28, 2018, 01:37:34 PM »

Another pic
another obvious thought , is the button catching the edge of the hole??    a bit of a rub with glasspaper maybe.  if wooden arms are warped and rubbing in it's "channel" then this is testing!!    can the arm be straightened slightly by wedging the button sideways for a few days?? any thing is worth a try. good luck with it..      brian..
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tom f

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Re: Old GDR box - stuck button
« Reply #10 on: November 28, 2018, 06:06:21 PM »

I think JD is probably right.  If you look at the third pallet along it is slightly cock-eyed and may be catching on the adjacent pallet.  the soluiton w might be to realign and re-fix the pallet.
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folkloristmark

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Re: Old GDR box - stuck button
« Reply #11 on: November 28, 2018, 08:36:15 PM »

The problem is often if you look accross  the fingerboard back , top to bottom alon the with of the instrument,it gets a curve end to end,Cheaap wood distortion.you will see it that makes the rod very hard to remove.If it is stiff  I concur with all the advice to avoid anything radical.I have, as Theo said been able to place an extra spring in the slot by manouvering it down the back slot. Using tweezers and long nosed pliers. It very hard frustrating and you need to compress the spring push in and release. It is possible given time and practice. It is hard to judge the spring balance with out doing it and if its too loose or firm need to be re do  with a selection of springs. Also be carefull not to lose any springs inside the keyboard as they will be very hard to retrive if they cause a problem.Another remedy quick fix, is to attach a regular type spring between the actual lever arm and a small screw into the Fondo.This will be hidden by the grill.Try it first with an elastic band and a drawing pin, to get the feel. The band eventually will disintergrate if left permanant.Not at home so can not post pics.If the physical issues are overcome and with good tunning you can get a very nice basic box out of these.
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Graham W

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Re: Old GDR box - stuck button
« Reply #12 on: November 29, 2018, 04:35:08 PM »

It's drastic, but there is enough clearance to be able to machine out the back of the keyboard to remove all the keys, replace all the springs and the axle with a stainless one and then make a new panel for the back of the keyboard.

Graham
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tom f

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Re: Old GDR box - stuck button
« Reply #13 on: November 29, 2018, 05:51:33 PM »

That's impressive!
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Dick Rees

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Re: Old GDR box - stuck button
« Reply #14 on: November 29, 2018, 05:51:55 PM »

It's drastic, but there is enough clearance to be able to machine out the back of the keyboard to remove all the keys, replace all the springs and the axle with a stainless one and then make a new panel for the back of the keyboard.

Graham

Nice!!!

I'd still give powdered graphite a try, though, for a quick fix.
« Last Edit: November 29, 2018, 05:53:29 PM by Dick Rees »
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Graham W

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Re: Old GDR box - stuck button
« Reply #15 on: November 29, 2018, 06:25:05 PM »

It's a silly amount of work for not the greatest of boxes so if powdered graphite keeps it going for a while that's for the best.
I just didn't want to be the one to condemn an otherwise functioing instrument to death!

I seem to recall with this specimen that the levers were also warped and binding in their slots so needed relieving slightly, quite apart form the broken springs it had in the first place.

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Fred

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Re: Old GDR box - stuck button
« Reply #16 on: November 29, 2018, 07:47:33 PM »

Wow. Thank you everyone, that's a lot of insight and experiences.

First of all I will trim the leather and the pallets so that they definitely don't interfere with each other. Thanks JD.

Then it seems as if I should try a bit of dry lubricant (whichever that may be... have to check what I have lying around in my tool closet). Thanks Pete.

If that does not work, I will in the long run definitely try to remove the back of the fingerboard. Awesome idea but a lot of work incoming. Thanks Graham.
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