Monday, October 28, 2013

potentiometer magic

Since using it with the Titan Ups, for about the fourth time now I've had to replace the tune knob on my Roland EP 7-II digital piano. The first time I did it I called around and got estimated to fix it for $100, plus parts. I looked a little further and found the part for $7 at a local shop and decided to try my hand at soldering it in myself. It's a a terrible design, and perhaps a terrible tuning potentiometer as well, as this part repeatedly breaks and makes my tuning go totally wonky and sound like crud.

Tomorrow I need to working to lay down some piano tracks for a recording the band did a while back, overdubs and perhaps re-dubs, or maybe just dubs, as it is a rocksteady reggae band. Tonight I spent about two hours opening the keyboard up and doing a total hack job soldering the new part in. This blog entry is a record to help me remember the steps in repairing it next time... and maybe help someone else.

 In the photo above you can see the tune knob and it's design where it sticks out from the back of the keyboard by quite a bit. This sucks. I drag this thing back and forth to practice and then about once a month to various bars around San Francisco. There is nothing to protect this knob from beating on the sides of my case and it eventually gets roughly tossed in the case in a frantic load-out off a stage somewhere and it destroys itself.

The idea that a keyboard needs a tuning knob is kind of ridiculous, but since it's there, it would be fine if the damn thing was flush with the back. But it's not, and when it breaks it tends to float down in tuning almost a full step. really, really annoying. We just played a show and I kept a guitar tuner on it to tweak between songs, and it fell out every song. So, here is how to replace the bastard:

First off, remove all the screws from the bottom of the keyboard. Keyboard will upside down, and you will have the foresight to put a towel under it to protect the keys. There are maybe 20 screws, and of these four are longer ones. I put pieces of gaffer's tape on the case to remember which holes take them. Also, two of these long screws don;t need to come out, but I forget which they are, I think the outer two. Sorry.. I took pics after almost put it together and thought blogging it might be useful. Put these in one bowl.

ramekins, good for baking flan and screw sorting
Look in at the main board (it's labelled as such) and remove the brass/ brass colored three screws holding the metal heat-sink holder frame on the board to the inside of the keyboard. Then also remove the screws holding it to the back of the keyboard housing. The two long screws are by the midi inputs and I believe there are three other, shorter ones. I put these screws all in a second bowl.

 Remove, GENTLY, the main board and set atop the back of the frame. I put a small blanket under it here. It will still be tethered to other parts inside via wiring. You don't need to undo this.

You can see the knob has two solder points on outer clips, and then three legs that are on inside. you can see the rather sloppy solder job I did last time. Keeps it obvious.

I touch these points with my solder iron until I am able to loosen the old pot and pull it out. I tried to melt out old solder to start with a clean board and holes, but don't have a good solder removal tool. The bulb thing I bought from Radio Shack is useless on a small spot like this.

Sweet salvation in the form of a new potentiometer. Ordered from Syntaur. I've also bought this in San Mateo from CAE Sound. This time they couldn't figure out a part number, so I paid for shipping from Texas.

 old / new

 Get the old one out, and hold the new one in and solder it to the board. Done. You may want to test that it works before you re-attach the 50 screws. I never do and it always fixes it, but then again I am awesome.... Writing this blog took longer than the whole project.
my set up, set up on my stove

If you're still curious, this video talks about cleaning potentiometers. I discovered it while repairing my stereo amp. Not only is this guy showing how to clean volume and tone pots, while sitting on a bed in a motel room, his accent is awesome. I love the way he says "potentiometer", it's nothing short of amazing :

Monday, October 14, 2013

Available for family portraits!

So a friend of a friend emailed me last week to ask if I would be interested in shooting her family's portrait for her mom's 70th birthday. Of course I'd love to, as this type of work is always a good challenge and keeps my skills honed, pays the bills, etc. Well. Then she mentioned that they might want to do a shot of them all jumping into pool....

.... oh HELL yeah, I'm interested!!!

I love people who like to have fun, and if that translates to doing something unusual to make a really fun photograph then all the more so!

We started with a group photo on the deck with an amazing view of San Francisco. While I guess, yes, it is maybe more iconic to see that other red bridge everyone likes so much from your deck, this view incorporates the way-more pragmatic feature of being sheltered from the westerly wind by the adjoining hillside. And the view is pretty darn cool..

The kids then came downstairs to pose along a tree for a second shot with mom. I love that little Annika was only interested in pulling Uncle Justin's hair!

Lastly, and perhaps my favorite outtake, Gaye and husband Donald pose with their pooch, oblivious to the kids photo-bombing the portrait....

Love it all!!!! And huge thanks to the Oswalds for making me a fun part of their lives for a day!!!!!

Wednesday, October 9, 2013

Arsenic and Old Lace

During a slow week last month, I decided to set up a lighting experiment with some old bottles I came across.

I should backtrack and say that I've been putting off the inevitable attention needed to work on a motorcycle rebuild, knowing there'd be lots of trial and error, and more error, and frustration, and etc. So before I felt like all that, I decided to clean the garage out and push further into the project with some elbow room.  I donated a few carloads of junk to SalArmy, and found these bottles in the mess. My sister Becca gave me them a few years ago, a gift from an ancient storage box at UFLs biology lab.

I mucked around with lighting for a while, but ended up using just two lights, heavily carding off various spill with black foamcore. Mixing stuff for an interesting filler got me thinking about arsenic.

Interesting to learn: The World Health Organization contends that a level of 0.01 mg/L poses a risk of 6 in 10000 chance of lifetime skin cancer risk and contends that this level of risk is acceptable (study of a mass well-water poisoning in Bangladesh). That noted, arsenic exists naturally, but poses a risk to human health when ingested in large doses. Over the years it's been used in various medicines, cosmetics, paints and then more famously as an instrument for murder.

I'd tell you what I used to fill the bottles, but then I'd have to kill you.