KARAOKE CHIP REMOVAL

Because the programmers who designed the GK600 series and N1-2 & N1-4 firmware have not supported the Yamaha YSS903 Karaoke chip (as the newer player's don't have them), if you just put in a GK600 series or N1-2, N1-4 firmware chip in a player that has the YSS903 the player will work but there is no sound. Technically what is happening is that because the GK600 series and N1-2, N1-4 firmware doesn't tell the YSS903 what to do, the serial digital audio signal (it is not proper audio yet) falls into a big "black hole". It enters the YSS903 but does not come out the "other end", and because of this the signal never reaches the digital-to-analogue converter (DAC) chip further down the line. The DAC is a PCM1720E device just to the right of the YSS903 on an ES4308 board and above the YSS903 on an ES4138 board.

You can use GK600, GK600A, GK600B, N1-2, N1-3 and N1-4 in a ES4308 processor board with no problems, just remove the karoke chip!

The trick is to somehow "bridge out" or bypass the YSS903 chip and therefore the sound gets to the DAC and in turn you hear audio.

However there is some good news! You may not have to remove the Karaoke chip to use GK600 series or N1-2, N1-3, N1-4 *PROVIDED* you connect your DVD player to a Dolby Digital receiver/amp by the digital output on the back of the AD-600A. Connecting your audio this way means the GK600 series or N1-2, N1-4 firmware is a straight swap for your older firmware chip..... No Karaoke chip removal needed! This applies ONLY if you use the digital output. Using the normal Left/Right analogue outputs requires removal of the Karaoke chip.

Please note: doing this modification removes the karaoke function from your player. Also note that if at any time you want to go back to older firmware that uses the YSS903 chip you do not have to undo the modification, unless you want Karaoke.

This is actually a simple process for anyone who has reasonable electronics and soldering knowledge. First, let's look at a snapshot of the two different PCB's which have the YSS903 chip:

The picture on the left is my ES4308 player and the one on the right is of an ES4318 equipped player. Note the yellow boxes showing the YSS903 chip. Your firmware chip is the long rectangle chip directly to the left of the ES4308 and ES4318 processor with the white sticker on it.

BEWARE!

This procedure involves some very delicate soldering work. If you are not sure you can do this DON'T DO IT! Give your player to someone who can or forget the modification altogether.

Ok, to do this modification you will need the following items:

*Some desolder wick (Optional)

*A fine-tipped soldering iron.

*A small flat bladed jeweler's screwdriver.

*Some "Wire Wrap" wire, or any other fine flexible hookup wire.

There are two ways to do this modification: Complete or Partial removal of the YSS903 chip.

METHOD 1: COMPLETE REMOVAL

Starting with the side of the YSS903 closest to the edge of the PCB carefully heat up one of the pins of the chip with the soldering iron with one hand. With the other hand use the jeweler's screwdriver to lift the pin clear of the PCB. DO THIS CAREFULLY OR ELSE YOU WILL LIFT THE WHOLE PCB SOLDER PAD OFF THE BOARD TOO! Continue down the length of the chip until you reach the end. Now do the same thing for the other side of the chip until it falls off the PCB. Now use some desolder wick to clean up the solder pads on the PCB (optional, but makes the job look better).

Now, with your hookup wire install three links where the YSS903M used to be as shown in these pictures. The one on the left is if you have an ES4308 processor on your PCB and the one on the right is for an ES4318 processor.

Interestingly it looks like this has been a "design" of the AD-600A all along because the PCB has three blank resistor locations already on the PCB for this modification as shown by the three outline boxes on the left picture for the ES4308 PCB. The three resistor locations on an ES4318 player are in a different position as shown by the outline boxes in the picture on the right. If you want to install your wire links at the resistor locations instead of on the chip solder pads you can. It is really the same modification.

Some people may have already noticed that the picture on the right is from an ES4318 PCB without the YSS903M and the three resistors already installed. If your PCB already looks like this (no YSS903 chip) then no modification is needed.

METHOD 2: PARTIAL REMOVAL

If you do not want to completely remove the YSS903 chip, you can use the above method of lifting the pins and only lift pins 1,2,3,4,6 and 28. Then you can install the wire links either on the solder pads where the chip pins used to be, or on the blank resistor locations.

The way you choose to do the modification is completely up to you.

Now all that is left to do is power up your player again and verify you now have sound. If not, check your work carefully for any mistakes.

IMPORTANT: DO NOT TAKE SHORT CUTS

I have been asked questions like the following email I received:

"I have a question on the GK600 upgrade and main board modification. Do you think it is possible to just short the three resistor pads and leave the Yamaha chip in place? This of course would probably mean unsoldering one (or more) of the power pins of the YSS903 from the board so it becomes dead in the circuit. The reason I ask is because this would make it much easier for the average Joe to do this modification if he doesn't have to remove the chip. Regards, Rick Holcomb. <rickh@dvd-wizards.com>"

Thanks for your comments, Rick. In answer to your question of lifting the power pins (pins 5,7,8,10,19 and 21) I do not recommend it. During my study of Advanced Digital Electronics it was made quite clear that just isolating power pins don't properly isolate all the pins of a chip. Even more dangerous than this is if you do not lift any pins on the YSS903 chip and just short the three resistor pads. This could cause two possible problems:

1. If you later decide to put in some firmware that uses the YSS903 chip, you could then get a conflict between the input and output serial data on the YSS903 which may damage something, possibly even the ES4308/ES4318 processor.

2. There is no guarantee that even if you are using GK600 or N1-2 firmware that the serial output pins of the YSS903 are "dead", and again you may damage something.

If you really want to leave the YSS903 on the board, do modification number two as described above and lift pins 1,2,3,4,6 and 28.

So what does this modification do? For the technically minded, it bypasses the YSS903 Karaoke chip so the signal can get though to the DAC chip and therefore to the line sockets.

The pins in question are:

Pin 1 (Digital Audio Serial Data Input) to Pin 3 (Digital Audio Serial Data Output)

Pin 2 (Digital Audio Bit Clock Input) to Pin 6 (Digital Audio Bit Clock Output)

Pin 28 (Digital Audio Word Clock Input) to Pin 4 (Digital Audio Word Clock Output)

You can download a copy of the YSS915 datasheet HERE. The YSS915 is functionally the same as the YSS903.