This butt-loop problem is a typical Yamaha problem. When surveying a Yamaha upright 30 - 40 years old that is one of the things to be aware of. The obvious clue is: are the butt springs sticking out instead of being retained by the loop? To change all these loops just takes time and I go about it in this way.
1. Make a tool to scrape out the old loop. I use the hook of a swivel-hooked plastic coat hanger as a basis. Break out that hook, bend over the serrated end to 90 deg, then file or grind that end to a 'V'.
2. Carefully remove one of the loops whole and measure its length.
3. Cut a piece of cornflakes carton (always have this stuff in the kit!) the width of the cord and bend it to form a tube.
4. Wind on 90 turns of new black loop cord and secure in place with a strip of masking tape, leaving the end of the masking tape protruding a good inch.
5. Now cut all those windings of loop cord along the tube's join and 'Voila!' you have 90 loop cords.
6. Stick your length of tape with loop cords attached to one side of the piano case.
7. Remove the hammer assemblies just one-at-a-time so there's no mix up.
8. Using your new coat-hanger gouging tool scrape out the old loop cord and immediately glue in a new one. I use PVA for this - but others may shudder at the thought!
9. Whilst that glue is setting take out the next hammer assembly and 'Go back to instruction No.8'
10. By the time you've glued in the second loop, the first should be ready to put back in the action. So re-engage the new loop to its butt spring and re-install in the action.
11. Now comes the interesting part: Align all the hammers to the strings exactly where they were or, better still, reface the hammer felts.
12. Job Done!
13. Good luck!
Michael (UK)
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Michael Gamble
semi retired
Brighton
01273813612
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Original Message:
Sent: 03-11-2014 13:00
From: Ruben Jackson
Subject: Silk cord replacement
This message has been cross posted to the following Discussions: In the Shop and Pianotech .
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Hi all,
I have a client who's complained about "squishy" action on her Yamaha console. I found that the silk cord is failing and she's asked for a quote to replace them all. I've done this repair to a few hammers at a time, but never an entire action. I'm interested in methods to do this efficiently, and whatever advice anyone here may have.
Also, am I on the right track with this being the correct diagnosis for this problem? A bit of regulation is also needed, which I will discuss as well with the client, but there is only minimal lost motion currently.
Please let me know if I've left out any important/helpful information.
Thanks for any help.
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Ruben Jackson
Jackson Piano
rubenjackon@gmail.com
www.JacksonPianoEastBay.com
(510) 859-8863
Berkeley, CA
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