Waldorf Microwave XTk No Power Fix
Synthesizers April 30th, 2013
The Waldorf Microwave XTk is the keyboard version of the Waldorf Microwave XT. It uses the same line-lump power supply, only it’s hidden inside the unit. The coaxial power connector normally used on the XT is covered up, and the power supply wires are soldered directly to the board.
There are many things that can make these synths not power up, but one common culprit is the transient voltage suppressor diode that is connected across the power input. This can fail to a short, causing it to appear that the power supply has died.
To troubleshoot, take the unit apart and disconnect at least one side of the power supply. Plug the power supply in. Does the light come on now? Do you measure ~12VDC at the output? If not, then the problem is probably a bad power supply after all. If so, then the problem is somewhere else in the synth.
Next, lift one leg of the transient voltage suppressor diode and use a meter to take an ohms reading across it. It should either appear open or have a very high resistance. If the resistance is low (like less than 1 ohm), then the part is bad. This very low resistance shorts out the power supply and makes it shut down.
Obtaining and replacing the diode is fairly easy and inexpensive. The part number is BZW04-15B and Mouser stocks them. Don’t worry about installing it the wrong way; it’s bidirectional.
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June 23rd, 2015 at 8:30 AM
Hey my Xtk display lights up green but doesn’t respond otherwise.
Can that be the diode or power supply? Also what power supply do I need (the manual says 1,2 Amp, 30 Watts with 120-240V input but doesnt say the output, I’m assuming its 12V DC like the cousins microwave xt and microwave 2). I read that mouser might have the part if I know which one to order.. thanks in advance for any help!!!
June 23rd, 2015 at 9:30 AM
I found the following power supply inside mine:
Delta Electronics, Inc. ADP-15ZB, 1,25Amps output, input 100-240v, 50-60hz. It seems to be meant to power Motorola Cable Modems so I wonder if it can even handle the 30 Watts needed. It runs about 20USD with shipping. Ordered the diode too just in case. I’m open to suggestions, thanks!
June 28th, 2015 at 9:35 AM
If your display is lighting up, then the problem is probably not the power supply or the diode. Start by sticking a meter across the power supply wires where they connect to the board. If you read 12V then it will confirm that your problem lies elsewhere.
12V x 1.25A = 15 watts, so definitely not 30. Everything I can find, though, says they only need 12 watts / 1 amp max, so your current (ha, get it?) power supply should be just about right (max load being about 80% of power supply rating).
Anyway, get in there with a meter. If you’re measuring 12V coming into the synth, then the problem probably isn’t your power supply (or diode) and it’s time to do some more troubleshooting.
September 30th, 2015 at 10:09 AM
If your display lights up but doesn’t fire up otherwise you probably have a loose molex header connector. Check the header connector from the panel board to LCD and also clean it if the leads are oxidised.
I chucked out my green lcd for a VFD and put orange plexi-glas over it.