Inside my Yamaha piano

This seems to be a common practice in consumer kit -- TV's, etc. Of course, for power, it usually makes sense due to the current carrying capabilities.

The actual connector (body) choice -- and thus the individual wire aspect -- may favor more "abusive" environments (?)

[Gives new meaning to "cut the BLUE wire!" (At least you'd know it wasn't the RED one!)]

If I'm seeing what you have correctly, the cables aren't simply point-to-point. Ribbon cables aren't a good choice for this sort of thing. Those connectors (again, if they're what I think they are) are quite inexpensive and very reliable. IOW, I don't see what you're griping about.

** Cos the terminations used in former are far better.

Crimp v IDC.

One of the most reliable v one of the worst.

With large numbers of links to make, IDC is more compact and cheaper.

.... Phil

I'm now free of the BPH agony. I can now drive to LA without a potty stop, and my wife can't. My Doc says I have the prostate size of a 20 year old; and my PSA readings are flat year after year. ...Jim Thompson

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I love to cook with wine.     Sometimes I even put it in the food.

Oooops! Wrong thread :-( ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

It was a simple question.

Why do people insist on reading non-existent stuff between the lines.

Sylvia.

krw is one of those polished objects that identify leftists >:-} ...Jim Thompson

-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

| 1962 | I love to cook with wine. Sometimes I even put it in the food.

Ok Jim, just don't tell us about your bowel movements.

Jamie

The practice of using individual wires is widespread. For example, a Yamaha SY77:

Inside my 1986 Korg DSS-1 synthesizer:

The ribbon cable on the left goes to floppy disk drive:

More:

My guess(tm) is that since the boards are mostly analog, the wires do not follow a topology where bus type wiring would work well. Since many of the wires carry analog signals, there might be a crosstalk problem if ribbon cables were used. The board tend to be spread out over the length of the keyboard. It's probably cheaper and easier to run a wire from one end of the machine to the other, then to try and route a trace through the PCB to do the same. The result is a sparse and clean PCB layout, and the cluttered wiring maze that you've discovered. Also, as Phil mentioned, IDC wire connections are lousy compared to crimp or solder connections.

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I haven't made a piano, but the ribbon cables in older computers and appliances are a pain in the ass. They're difficult to route and rigid enough that they would slice themselves open when settling into a new position. The only thing they're good for is transmitting high frequency signals in phase.

The separate wires are very flexible, not prone to damage, and can be wrapped with sticky cloth for extreme vibration resistance.

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Multiple wires may be more flexible. Are there crimped ends on the blue wires? That may be why.

--
Les Cargill

Sometimes this happens when all the wires start in the same place but not all of them end up in the same place - in other words, a Y cable.

You can make a Y cable with most kinds of ribbon cable, by splitting the cable in the middle - sort of like lamp cord. One end has, say, a 20-pin connector, with 20-wire cable. Then the cable splits, and the first 4 wires go to one connector and the next 16 go to another.

If one leg of the Y is much longer than the other, you waste a certain amount of ribbon cable. Also, if the ribbon cable only has one wire marked for position, you lose that marker when you split the cable, making it more likely that somebody will install the connectors wrong.

I suspect that there are automated machines that will install the crimp terminals on the wires, and probably stuff the installed terminals in the connectors in the right order. At consumer-product volumes, companies will spend a lot of money on tooling to lower the overall cost.

Matt Roberds

As an aside, I was looking at the connector to the keyboard.

It has 8 wires.

So, one for power, one for ground. Perhaps one for clock, so leaving either 5 or 6 for data.

Which seems an strange number. The keyboard has 88 keys, so there are not enough wires to send a key number in parallel.

OK, that doesn't mean much - the protocol could be anything.

All the same, if they're saving on wires, four, or even three, would have done.

Sylvia.

It's probably velocity sensitive, which would require at least two contacts per key (to measure the time between first and second contact). My keyboard (Kawai VPC1) has three contacts per key, and uses 5 timing signal wires with a binary count, with 12 pickup wires for closure detection. So, 17 wires to pick up 264 switches (plus power and ground). The binary count is decoded by LS138s on the keyboard module to 22 timing signals driving the switch commons.

Mine also uses separate wires, and no ribbon cable at all.

--
John

I suspect it has differential data lines to reduce bulky shielding and carefully routed signal grounds that would otherwise be required for live performances.

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Have you looked *inside* the keyboard (i.e., to get an idea of what sorts of electronics may be hiding within)?

Large "keyboards" (musical instruments, mixing consoles, video switchers, etc.) typically have "smarts" in the keyboard itself (e.g., a dedicated processor).

Consider that the piano is undoubtedly polyphonic so "simple" decoding schemes won't work (well).

Also, are there any (likely) dedicated signals that are implemented on/in the keyboard that could mandate dedicated conductors? (e.g., a power switch, an audio monitor jack, etc.)

Not going to tell you the gory details about my prostate. BTW What electronics thread were you discussing your prostate, anyway?

If interface protection would be the main objective, a ribbon cable would be much better with every other conductor as the signal ground or the antiphase of a balanced connection.

Better yet use twisted pairs for balanced connections.

Looking at the picture, EMC was not the primary cause for using that kind of random wiring. As other have pointed out, more likely are various point to point or point to multipoint connections.

If you have a "harness department" making prefabricated cable harnesses using some degree of automation, why not use it ?

You're griping about the construction of your piano, which is perfectly fine. I'd have made fewer assemblies and fewer cables but it's hard to know what their design requirements (AKA, economics) were. The IDE cables you're so enamored with are crap.