Thursday, July 24, 2014

Adventures in Digital Piano Electronics Part 2: More Diagnostics and Repair

In the first part, I discovered a blown resistor, so I took what was left of the part to Radioshack in hopes of finding someone who could help with finding the part. Upon getting there, no one seemed to know what was going on, they just wanted to sell a device to read the resistor but we were thinking it probably wouldn't give an accurate reading if it was blown, so we left.

I went back home and looked around the motherboard for some clues to the blown resistor and figured I'd just buy a bunch of parts and see if I could find anything that matched. Nothing. However, upon this second matching game, I discovered another culprit: a blown capacitor. This capacitor was actually the constant to help with finding my unknown resistor variable in the busted piano equation. On the capacitor, it stated the size which was 470uF35v. Right next to it on the motherboard was the same size along with the number that I'm assuming goes with a schematic drawing somewhere in the Williams Symphony assembly archives. Next to the blown resistor was the same information part R54 100. I looked around for that same part number and to my luck found one! A little blue resistor with what looked like a Brown/Black/Black/Black/Gold scheme. Upon reading color coding of resistor bars, it corresponded with 100 and so long story short, I had more information as to what I needed.

I went back to Radioshack a few days later and told the guy I needed to return the part and asked if he knew if they had the specific resistor I was looking for and he said, "I don't really know about that stuff." Awesome. I kind of felt like Parker Posey in Best in Show when she's asking the guy in the pet shop about the Busy Bee toy and keeps getting all these other toys and the salesman is just confused as to what to do.

I wound up buying a resistor multi pack figuring my part was bound to be in there (as it did say it contained not one, but FOUR 100 ohm resistors. As for the capacitor, that was a pretty quick find. I paid and was short something like $6 for everything.

When I got home, I tested the parts out to make sure they worked and they didn't with the speakers on. I plugged in the jack and it worked! I looked back on the motherboard to try and figure out what was wrong and realized we unplugged the speakers to get access under the motherboard. It would work!

Next, I busted out the solder and soldered those parts in place, trimmed the excess and added a little more. They were pretty sloppy solders, but held up.



 Who solders in a dress? ME!

What can I say? This is my first time ever doing anything like this, so I'm happy with the results. Not perfect, but functional. My piano is now a beater!



 What's that sound? That's what winning sounds like! Digital Piano Electronic Repair was a success and my curiosity saved me a lot of money.


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