Modifying your player to make a FlashROM work in a PROM/EPROM player or vice-versa

The latest release of the AD-600A has a FlashROM on the circuit board, whereas the older models come with only a PROM. What is the difference? As far as the player is concerned there is no difference. They both have the same memory capacity and can store the same firmware, but electrically there is a slight difference with two of the pins. You can not just put an EPROM into a player that has a FlashROM installed.

So the question is can a FlashROM be used in a PROM/EPROM board, or vice versa? The answer is YES!.

THE ES4308 PLAYER

For the ES4308 processor player they never came out with a FlashROM factory fitted, only a PROM. However they also have the resistor options for a FlashROM as shown here:

On a PROM/EPROM fitted player the resistors are installed at locations R41 and R46 while R42 and R44 locations are blank. To fit a FlashROM is easy! Just remove the resistors from loactions R41 and R46, and re-install them at locations R42 and R44. The resistors are both "zero ohm" type so it does not matter if you mix them up. If you damage or lose them (they are small!) do not worry. Just install wire links instead.

THE ES4318 PLAYER

The ES4318 processor player can have either a PROM/EPROM or FlashROM fitted depending on when it was made. Look at these two pictures:

At first glance there is no difference. Right? Wrong! The left side is a FlashROM fitted player while the right side is a PROM fitted player. But they look the same... Correct, but look closer. There are two ways you can tell the difference:

Method 1
The left one says (once you remove the sticker) "MM29F040" and the right one says "AT27C040". This may not mean much to you BUT if you have a look at the datasheets on these chips, the 29F040 is a 4Mbit FlashROM and the 27C040 is a 4Mbit PROM.

Method 2
Notice the orange rectangles. For the FlashROM fitted player there are resistors installed at locations R42 and R81 and locations R41 and R80 are blank. For the PROM/EPROM fitted player it is the reverse: R42 and R81 are blank while R41 and R80 have the resistors.

To make a FlashROM work in a PROM/EPROM player move the resistors from R41 and R80 and re-install them in locations R42 and R81.

To make a PROM/EPROM work in a FlashROM player move the resistors from R42 and R81 and re-install them in locations R41 and R80.

The resistors are both "zero ohm" type so it does not matter if you mix them up. If you damage or lose them (they are small!) do not worry. Just install wire links instead.