Adventures in creating and destroying sounds
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  • Replacing a blown tweeter in a Behringer B215A Powered Speaker

    Posted on December 7th, 2010 Bob 42 comments
    Introducing the Behringer B215A

    Introducing the Behringer Eurolive B215A PA

    I picked up a Behringer B215A Powered Speaker and it served me well for just under a year. I somehow blew the tweeter during a Xome performance! Imagine that!

    By the time I thought about it again and went to dig out the warranty information, the one-year warranty period had expired. Pretty typical thing for me to do. So I figured that I’d crack ‘er open and see what going on in there.

    Screws on the back of the B215A with some notes

    Screws on the back of the B215A with some notes

    Opening up the cabinet was easy enough except some of the screws holding the thing together were recessed so far down in the back of the cabinet that my trusty screwdriver would not reach. Actually, most of the screws were that way. I went to the hardware store and picked up an extra long Philips screwdriver — a 20 inch long one to be exact. I measured things up and you would need at least a 9 inch long shaft on the screwdriver to get these screws out. Most of the screws were the same but there were two that were shorter than the others and the screws used for the handles were different.

    The speaker cabinet is open

    The speaker cabinet is open

    So, after all the screws were out, the front and the back of the speaker came right apart. If you are doing this yourself, be extra careful as both the front and the back are big and heavy and could fall over. Prop up one side on a wall, chair, table, etc. You don’t want one side falling over and yanking too hard on the wires.

    When I got to the point where I could  reach inside the speaker, I marked a + and – on the respective connectors with a Sharpie for both the compression driver (tweeter)  and the woofer. I also marked each of the wires themselves as “woofer” and “tweeter” so I wouldn’t get those mixed up.  Then I removed the quick disconnects on each set of speaker terminals. Now the cabinet is in two pieces!

    Original Behringer compression driver mounted on the horn

    Original Behringer compression driver mounted on the horn

    The compression driver on these speakers screw right in to the back of the horn. Simple enough to remove, right? I twisted and turned it but it would not budge. I expended all my vast muscular energy on it and could not get it to twist off. I noticed that the diameter of the compression driver was about the same as an oil filter on a car. A quick measure told me it was 3.5″ in diameter.  So I went and picked up a cheap oil filter wrench. The oil filter wrench worked flawlessly. The magnet in the compression driver did attract the metal on the wrench a bit though. A couple of light taps and some twisting and the driver was off!

    I got the compression driver off with an oil filter wrench

    I got the compression driver off with an oil filter wrench

    Behringer uses some sort of loc-tite material on the threads to secure everything in place making it difficult to remove.

    I did a little research online and found that the threaded opening on the Behringer compression driver is actually a pretty standard size — 1 3/8″ in diameter with 18 TPI (threads per inch). For a replacement, I wound up going with a Selenium D220TI (8 ohm) available at Parts Express. It cost me $45.84. There was another one available in the $30 – $40 range but I decided to go wit the D220TI  because of the rated power handling. Supposedly the original Behringer HF compression drivers replacements run in the $70 – $80 range. The few places that I found online indicated that they are “special order” items and it would take a while to get them to me. The specs on the Selenium are better, it was around half the price and I could get it in a few days so the decision was pretty much a no-brainer. There was also another consideration in the decision process… the Selenium has a titanium diaphragm and the original Behringer 34T30D8 has an aluminum diaphragm according to the markings on the driver.

    Original Behringer 34T30D8 Compression Driver

    Original Behringer 34T30D8 Compression Driver

    Now, when I purchased this speaker, I was under the impression that it had a titanium diaphragm driver… the box it came in says it has a titanium diaphragm driver… Behringer’s Web site says it has an aluminum diaphragm driver and some retail Web sites say it has a titanium, others say it has an aluminum.

    Original box the Behringer Eurolive B215A came in

    Original box the Behringer Eurolive B215A came in

    I feel that there’s something weird going on so I’m probably going to write a nice letter to Behringer to see what they have to say… but I digress…!

    Selenium D220Ti Titanium Horn Driver (8 Ohm)

    Selenium D220Ti Titanium Horn Driver (8 Ohm)

    So, I popped in the new Selenium driver, reconnected the wires and put everything back together. The Selenium is a lot bigger and heavier that the Behringer counterpart but it screws on to the back of the horn and fits inside the cabinet just fine. The oil filter wrench won’t strap around the new driver — it was just way too big. I just screwed it in as tight as I could by hand.

    As for the sound, I have only done a brief test bit it sounds excellent. I hope that the new Selenium driver will hold up to the abuse I sometimes put it through.

    By the way, the Behringer B212A supposedly uses the same setup except the woofer is a 12″ as opposed to the 15″ in the B215A. You should be able to replace the stock Behringer compression driver with a new one like I did.

    Here are some extra photos:

    The amplifier side of the Behringer B215A

    The amplifier side of the Behringer B215A

    The big ol' 15 inch woofer

    The speaker side of the Behringer B215A

    The 15 inch woofer

    The big ol' 15 inch Behringer woofer

    The original Behringer compression driver is out

    The stock Behringer compression driver

    The new Selenium D220Ti ready to go in

    The new Selenium D220Ti ready to go

    The new Selenium D220Ti is in and ready to go

    The new Selenium D220Ti is installed

  • Installing a New Battery in a Yamaha DX7

    Posted on September 26th, 2009 Bob 36 comments

    I recently had the chance to replace the battery in a Yamaha DX7 Synthesizer. The manual for the DX7 states that the battery should last for 3 to 5 years and it was well past that time. I first thought that I could just run down to Walgreens and pick up a “button” style battery and pop it in but after poking around on the Web, I found out that the DX7 uses a special kind of CR2032 battery with solder leads mounted on it. I found a suitable battery through Mouser (part number 614-CR2032FH-MFR). To replace the battery you basically have to take the whole synth apart, but Yamaha tries to make the procedure as painless as possible.

    I found some very helpful instructions through Dave Benson’s DX7 Page (also archived here) for replacing the battery. These instructions were spot-on!

    There were a couple of things I noticed while disassembling the synth.

    1. The connector labeled C6 on the main board is not connected to anything.
    2. The main board was a little difficult to remove from the chassis after all screws and connectors were out. There are two tabs that are used to mount keyboard. You have to angle the main board between these tabs and the back of the chassis to lift the board out. Be careful when doing this!
    3. To remove the old battery, I used a solder sucker to get rid of most of the old solder which makes it easier for the old battery to pry up and out.
    4. The battery evidently had been replaced before. There was a service sticker from some repair shop on the back of the unit. The trace between the battery’s positive lead and the next component (which is a diode) had been severed. I had to solder in a short jumper over the trace to fix it.

    Overall, replacing the battery was not a difficult task but somewhat time consuming. Have fun!

    You can click on the images below to get a larger image:

    Yamaha DX7 open with keyboard in place

    Yamaha DX7 open with keyboard in place

    Yamaha DX7 close-up of connector C6

    Yamaha DX7 close-up of connector C6

    Yamaha DX7 open with keyboard removed

    Yamaha DX7 open with keyboard removed

    Yamaha DX7 main board

    Yamaha DX7 main board

    Yamaha DX7 solder side of main board near battery

    Yamaha DX7 solder side of main board near battery

  • Replacing a non-operational motor on a Tascam Portastudio 424 MKII

    Posted on February 10th, 2009 Bob 38 comments

    tascam_portastudio_424_mkiiI was fortunate enough to pick up a used Tascam Portastudio 424 MKII about 4 years ago on Craigslist. It worked flawlessly when I first got it. Recorded many a Xome tracks on the beast and eventually set it up so that the output of the 4-track was plugged into the soundcard on my computer. It was so handy having this setup to try out new gear and record that the Tascam almost never was powered down.

    I decided to check out some old 4-track tapes recently and noticed that when I pressed play, rewind or any of the other tape transport buttons that the appropriate light would come on for a few seconds, some clicking was heard but it pooped-out.

    I decided to open her up and poke around a bit. I noticed that the motor underneath the cassette tape bracket seemed like it wasn’t moving when perhaps it should. After taking out the bracket and looking at the motor, I did a quick Google search on the part number printed on the motor’s label (which proved not as fruitful as I thought it might be). But I finally found a place in Indiana called Studio Sound Electronics that carries the exact replacement. I found from the information on their site that it was a 12-volt Mabuchi motor. I placed 12-volts on the motor and yup, no movement.

    I decided to order a replacement from Studio Sound Electronics. The motor was $9.95
    And shipping to California was just under $5. I must say that Studio Sound Electronics’ service is wonderful. The motor arrived just a few days later.

    I popped in the new motor, soldered the 4 wires into place and put everything back together. Bam! Works like new again!

    Here are some hints if you’re looking to do this repair yourself:

    ** There are about 15 screws on the bottom of the unit that need to be removed including one that is on the little “ledge” on the back of the 4-track.

    tascam_openhood** After carefully opening up the unit, you have to disconnect 5 connectors – 4 from the big circuit board and one two-position connector from behind the transformer. Since they are all different positions and there are slots so you don’t put them in backwards, it’s not really necessary to mark them or anything like that.

    tascam002z** Remove the connector from the back of the cassette tape bracket.

    ** Remove the entire bracket assembly with the screws on the top of the bracket.

    ** Remove two screws on each side of the bracket to access the bottom bracket that holds the motor. One on each side is screwed through a plastic clip thing. tascam002You might want to put these away carefully so that you get the plastic clips on the correct sides when you put it back together.

    ** Move the motor’s belt over to the side and remove the 3 flat-headed screws that mount the motor. Gently pull off the belt guide.

    ** Once the motor is free, cut the 4 wires connected to the motor. You may want to memo where each of the wires go. The wires go as follows: A: blue, B: yellow, +: red, -: black.

    tascam_motorback** Strip each of the wires (about 3mm will do) and solder the wires on to the new motor.

    ** Putting the 4-track back together is the reverse of taking it apart. Just make sure you have all your electrical connectors connected!

    tascam_motor** The motor in the Tascam 4-track is a Mabuchi Motor EG-530KD-2B. It’s a 12VDC 1600/3200 RPM CCW (counter clock-wise rotation) motor. It’s available from Studio Sound Electronics at http://www.studiosoundelectronics.com/cassette.htm