Category Archives: Electronics

Magic Sing Karaoke Microphone Tear Down, Part 1

I bought this Magic Sing Karaoke microphone system many years ago and my family and friends have enjoyed and some times been annoyed by it quite often!  It truly is a really neat gadget..  I’ve got a plethora of photos of the inside, the outside and the on screen displays.

The microphone base has 2500 songs built in, and has several add on slots for song chips that are available online for about $60 a pop.

The base also has an SD card slot, but it is not for songs.  It is only used for storing user content, photos, backgrounds, movies and songs recorded live.

The system includes two cordless microphones that also each act as a remote control.

The model # I have is the ET19KV.  I originally paid $499 for it!  But that was like eight years ago!

Under the top cover of the base unit we find the slots for expansion chips.  I’m impressed by the number of slots.  Some song chips have 200, 400 songs!  But most have between 60 and 100.  The songs are of the MIDI type.  You can watch the video at the end of the article to hear the actual sound quality.

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The rear of the base has the output connections:

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The wireless microphone antenna:

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Let’s open it up!  Don’t tell my wife!  At least I put it back and no extra screws were left!

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Interesting things in here.  The big black parking lot sized chip on the left is an FPGA!  The chip on the right is a flash memory chip, which holds the circuit design for the FPGA.  If you’re not familiar with FPGAs, they are essentially a blank canvas for creating eletronic circuits using logic gates.  They have millions of gates or connections that can be configured into just about any digital circuit imaginable.

 

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I’m very curious about the squigly lines shown above.  These traces, they were intentionally designed that way, I wonder why?

The chip on the bottom left of the below picture is the NTSC/PAL video encoder/decoder.

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Another big chip!  This one is a Sunplus DVD/Mpeg1/2 decoder.  I suppose this is for playing movies off the SD card:

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You can store Karaoke Movies on an SD Card and play them on the MagicSing.  There is special software called MagicSing Encoder that you need to use to get the best results.  There are lots of sources for Mp3/CDG files that can be converted to the video format usable on the MagicSing.  You can scrounge up CDG discs at yard sales etc and rip them to your hard drive if you have the right CD reader.

 

Here is the song chip.  This chip holds 200 songs.

The card edge connector is a 40 pin, 2 position, male variety.

The contacts are about 0.050″ (1.27mm) pitch.  Hard to measure!  The card is .031″ thick.

The actual chip inside is a NOR Flash variety.  Some information about NOR vs NAND memory chips:

https://focus.ti.com/pdfs/omap/diskonchipvsnor.pdf

The connector looks like a Harting 40 pin Motherboard to Daughterboard:

https://b2b.harting.com/ebusiness/en_us/PCB-connectors-Micro-Card-Edge-Connector/391899?showProducts=1

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This is a Spansion S29Gl064N90TF104 64 megabit NOR flash chip, storage space is 8 megabytes.  It is a 48-pin TSOP.  22 Address pins, 15 data pins. It can operate in 8 bit or 16 bit address/data communications.

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This is a 40 pin edge card connector.  I’ve got a temptation to hook this up to my mbed enabled STMicro nucleo board and download the data to see whats in it!  The nucleo board is an ARM powered development board that costs $10 and has plenty of IO pins to connect to this chip.  I had thought seriously about trying to decode whats on this chip but in the end it will be fruitless.

Some work has been done by some smart fellas on NAND flash chip bit banging through the FTDI break out board.  I wonder how this could be adapted to the NOR chip?

https://github.com/cyphunk/ParallelFLASHDumper

https://recon.cx/2014/slides/Reverse%20Engineering%20Flash%20Memory%20for%20Fun%20And%20Benefit.pdf

Now for some screen shots.

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Using a permanent marker to make circut boards

I’ve been considering the best approach to making my circut boards with the Cricut Expression (aka FreeExpression).

The board design software I use is called Eagle Cad.  It is free for small designs and can generate HPGL files that I can send to the Expression via my custom firmware.

First off, I’ll need a suitable pen that will produce ink which can survive the etching bath.  The go-to marker for this purpose is the Sharpie ultra fine permanent marker.

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However, in my past experience with this marker, the results were less than desirable.  The copper under the ink will be pitted and can result in open connections on fine traces.

I’ve had much better luck with the Staedtler Lumocolor Fine Point Permanent Marker

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These pens are pretty expensive too..

If you can’t find them at your Office Depot or Staples in the Pen/Markers section, look in the Drafting Supplies section.  That’s where I found mine.

Do not buy the Staedtler Fine Pigment Ink Archival pens.  They do not work at all.  (See below).

I bought two sets of pens.  The Staedtler Lumocor set of colored pens, and a set of four Staedtler Pigment Ink Archival pens.  As  a writing instrument, these archival pens are incredible.  They write so fine, and the ink is acid free, waterproof, won’t smear or smudge.  It’s awesome.  As a PCB writing tool, forget it.

I grabbed a scrap board and used each pen to write the color name.  Then I used each of the archival pens to write the point size.

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Then I headed to the Ferric Chloride bath.

If you don’t want to use Ferric Chloride, read this article for a home made alternative.

After 45 minutes, had my results.

First observation: 45 minutes was too long 🙂  Probably somewhere between 30 and 45 minutes.

Second observation:

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So, ranking the colored pens in order of preference:

  1. Black
  2. Green
  3. Orange
  4. Brown

The rest were unusable IMHO.  Red used to work a few years ago.  Seems they changed the formulation.  I’m going to repeat this test using Acid/Peroxide mixture.  Another alternative is Sodium Persulfate.  I have some Ammonium Persulfate on hand, but it is hard to get the mixture right.  Problem with both persulfates is that the mixture loses it’s strength over time, so letting it sit on a shelf for a couple of weeks it will be useless.  Not as long lived as Ferric Chloride.  The Acid/Peroxide mixture etches much faster though.

Be sure if you use acid/peroxide, do it out doors.  My workshop is poorly ventilated so I can’t use that stuff indoors.

To be continued…

Repairing a damaged surface mount resistor

Well, somehow I managed to damage a resistor that is connected to the ISP header (J5) on the expression’s motherboard.  This led to a confusing error message in AVR Studio when I tried to program the flash on the Atmel chip.

The error message said “Failed to connect to target.  Does the target have power?”

Referring to my previous image on the JTAG interface, I recognized this pin, VTRef, which is pin 2 on the connector:

CricutExpressionJtag

Just to the right of the connector, off screen in the above image, is a tiny surface mount resistor.

I had carelessly plugged the ISP cable (which goes in the black connector in the bottom right above) into my AVR Dragon programmer’s JTAQ port!!!!  Argh, so this sent voltage back down to pin 2, which fried the resistor.  During inspection of the board when I could no longer program the code, I saw some brown residue next to that resistor.

Using the voltmeter when the machine powered on, I confirmed that I had 5 volts going into the resistor, and zero volts coming out.

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Now I had to find a spare board with a similar sized resistor… and use my shaky hands to dismount it and re-solder it onto my machine’s motherboard.

So, once I removed the resistor and replaced with a similarly sized one, I tested the voltage going in and out, seeing that it was both 5v, I reconnected the AVR Dragon’s ISP cable (to the correct port this time!) I successfully read the chip and received no errors…. yayyyy!