Categories
Analog Electronics Music

Wurlitzer 200: Fixed

I am very excited to announce that the Wurlitzer 200 is fixed and operational. I say Wurlitzer 200 instead of 200A because a nice chap emailed me and let me know that I actually had an earlier model. Either way, it works and it sounds delicious.

Wurlitzer 200

Really this post is to gloat a little and to post the sound samples I recorded with my friend Joe. He is a great piano player and shows off the awesomeness of the Wurly better than I ever could. I also wanted to lay out some future posts about the Wurlitzer that I plan to write:

  1. Things learned about fixing the Wurlitzer. Schematics and my own drawings included.
  2. The importance of grounding for a clean signal and how it can affect other types of electronics.
  3. How transistors work and how the broken transistor on my Wurly was causing me grief.
  4. How fuses work and when to use them.
  5. Any others requested/suggested through the skribit box on the right.

Finally, here are the sound samples Joe and I put together today. It was fun recording again. For full disclosure, there was digital delay on the Wurly and there was some processing on the drums too. Also, I apologize that the drum tracks are a little loud; it’s because I’m an electrical engineer, not a sound engineer (and definitely not a professional musician). Enjoy!

Categories
Analog Electronics Learning Music

Update: Wurlitzer 200A–Still in pieces

I thought I would update on my hobby subject for tonight since I mostly worked on my Wurlitzer 200A electric piano instead of writing the post I meant to. I’m just now getting back into working on my electric piano after previously having zapped something on the board and not being able to get it working since. When I messed up last time I was actually trying to replace the capacitors and transistors that had dried up; I had thought these were causing considerable hum in the circuit. However, since deconstructing the piano I found a modification to the wiring scheme between the two speakers and the output headphone jack located at the bottom of the board. I found that on the headphone jack someone had wired in a simple RC circuit, presumably for filtering the headphone output. However, the small wiring scheme they used and meant to ground to the chassis had been disconnected, possibly by me. This floating output circuit could have been the problem all along! Only time will tell but I will feel silly if that was indeed the culprit.

Still, I always prefer a silly mistake that is found and easily corrected (with damage only to my ego) , as opposed to a difficult error that cannot be fixed or worse, found. See the pictures below of the destruction that has befallen my piano and hope that I can get humpty-dumpty back together again.

The main board, removed from the chassis. With new electrolytic caps.

The piano with the chassis and the board removed. The speaker assembly and the transformer are all bolted to the main chassis, which is convenient when you want to work on the action of the keys (how the hammer hits the tone bars).

The slew of new components I got in from my online order…and now may not need?

It’s not the wand, it’s the magician. In this case, the wand is a piece of junk soldering iron from Radio Shack. Maybe Santa will bring me an industrial voltage controlled soldering iron.

Categories
Analog Electronics Life Music

Breaking my Wurlitzer 200A

“Hmm, I should really get a sound sample for the before and after on my piano. I’m so confident I can get this thing to work that I want some evidence how broken it was prior to my genius fixing of this machine.”

POP. ZAP. HUMMMMMMMMMMMMMMMMMMMMMMM.

“EEP,” thinks Chris.

HMMMMMMMMMMMMMMMMMMMMMMMMMMMM….

So it seems that I may have broken the amplifier on my Wurlitzer 200A. This after I took my sweet ol’ time getting all the replacement parts in from Mouser. After they finally arrived, I scheduled a time to work on the piano on the weekend to try and fit into my relatively busy schedule.

First inspection of the board shows that this piano has definitely had work done on it before. There are multiple places where the solder joints have been over done with solder (too much globbed up in one place). The resistors and capacitors also do not appear to be the originals, though they still appear to be pretty old and could be the originals.

So what do I think happened? In my onomatopoeic description at the beginning of this article, you may have guessed that there was a short to ground (the “ZAP”). This happened because I was dumb enough to try turning on the piano when it was not bolted to the chassis. The circuit board likely shorted from one of the high potential points to the chassis, which is grounded. In the process, high amounts of current either caused a part to fail catastrophically through material failure (a PN junction having too many carriers “break through”) or thermally (an electrolytic capacitor exploding due to high temperature).

I have a very primitive multimeter intended for use on power lines and such, so it could only tell me the there is 2 volts DC at the speaker output. This is definitely not healthy for the speaker nor the system and leads me to believe the output coupling capacitor may have broken. I will update more once I borrow my friend’s advanced multimeter.

Categories
Life Work

New Year’s Resolutions

I’m not one to make resolutions. Personally, I think many times people are setting themselves up for failure when they pick a random day to start doing everything they meant to in life, especially the big broad goals. However, in the spirit of the season, I’m going to throw everything I just mentioned out the window and list some stuff I want to do this year, mostly so I have these things recorded somewhere I’ll view them again.

  1.  Gain 10 pounds of muscle by April. Achieve this by going to the gym at least 2 times per week and doing high intensity lifting workouts.
  2. Be able to play a Chopin piano piece. Also, be able to improvise with piano over a simple chord progression (ii-V-I)
  3. Join a band and play 1 gig in the next year (drums)
  4. Increase my investing prowess by reading annual reports of all currently held stocks and doing thorough analysis of any new stocks that interest me.
  5. Finally and most importantly, I would like to find work that is more fitting to my personality and needs. However, I would like to make sure this position leaves me enough time to live life and spend time with those I love. I am willing to sacrifice money and possibly even my future career prospects to achieve this goal. This means I desire to:
    1. Work roughly 40-45 hours per week (the most negotiable of these desires)
    2. Have flexible vacation time and some amount of assurance that I will not be working on major holidays.
    3. Given responsibility and be judged on merit, and not time spent at the office.
    4. Be driven to create value and something of use to the world and my company
    5. Enjoy spending time with my co-workers

The last item about work is indicative of my generation. We realize that work is a main part of life and want to integrate it with all other aspects of living. To do so I think I need many of the things listed above. To end this post, I will paste in a story that I have sitting by my desk at work and read just about every day. I must admit, I found the story on the wall at Jimmy John’s first (my favorite sub shop), but it was too good to pass up. Here it is with the link where I found it. I hope it helps to illuminate how I think about work.

An American tourist was at the pier of a small coastal Mexican village when a small boat with just one fisherman docked.

Inside the small boat were several large yellowfin tuna. The tourist complimented the Mexican on the quality of his fish and asked how long it took to catch them.

The Mexican replied, “Only a little while.”

The tourist then asked, “Why didn’t you stay out longer and catch more fish?”

The Mexican said, “With this I have more than enough to support my family’s needs.”

The tourist then asked, “But what do you do with the rest of your time?”

The Mexican fisherman said, “I sleep late, fish a little, play with my children, take siesta with my wife, Maria, stroll into the village each evening where I sip wine and play guitar with my amigos, I have a full and busy life.”

The tourist scoffed, ” I can help you. You should spend more time fishing; and with the proceeds, buy a bigger boat: With the proceeds from the bigger boat you could buy several boats. Eventually you would have a fleet of fishing boats. Instead of selling your catch to a middleman you would sell directly to the processor; eventually opening your own cannery. You would control the product, processing and distribution. You could leave this small coastal fishing village and move to Mexico City, then Los Angeles and eventually New York where you could run your ever-expanding enterprise.”

The Mexican fisherman asked, “But, how long will this all take?”

The tourist replied, “15 to 20 years.”

“But what then?” asked the Mexican.

The tourist laughed and said, “That’s the best part. When the time is right you would sell your company stock to the public and become very rich, you would make millions.”

“Millions?…Then what?”

The American said, “Then you would retire. Move to a small coastal fishing village where you would sleep late, fish a little, play with your kids, take siesta with your wife, stroll to the village in the evenings where you could sip wine and play your guitar with your amigos.”

Reposted from http://www.noogenesis.com/pineapple/fisherman.html