[Home]

Wiring Information for a Syntor PL PROM to EEPROM Adapter:

Note: this home brew adapter is fairly difficult to construct - mainly because it is a very tight fit into the space available. Once completed though, it works well and is easy to use since the EEPROM (or EPROM) can be removed and replaced for easy programming or re-programming.

The diagram below can be used to make an adapter that will permit the use of a 2804 or 2816 type EEPROM to replace the Syntor PL PROM. The adapter (with minor changes which are shown in the table below) can be constructed using a 2716 or 2732 EPROM (NOTE: it is easier to fit these 24 pin EPROMs into the available space than to use 28 pin EPROMs or EEPROMs such as 2764, 2864, etc.) NOTE: where a pin of the EEPROM or EPROM appears in more than one line of the table, be sure to use the line which corresponds to the device you are using (i.e. 2804, 2816, 2716, or 2732).

Since the space available for the Syntor PL PROM is VERY LIMITED, I construct this type of adapter as follows:

1.) I remove the PL PROM and its socket from the Syntor PL encoder/decoder circuit board.

2.) I replace several of the resistors that surround the PL PROM socket. These stand "upright" and would interfere with the space for the adapter. I replace these resistors with ones of the same value that I can install "lying down" (i.e. parallel to the circuit board). I have used 1/8 or 1/10 Watt resistors (sometimes) for these replacements due to their smaller size.

3.) I manufacture a sort of "header" by stacking some small pieces of "perf" board. The pieces closest to the circuit board are the size of the PL PROM socket (i.e. about 0.5 inches wide and 1.1 inches long) and contain an array of holes on 0.1" center that is 4 holes wide and 10 holes long. The piece furthest from the circuit board is sized to accommodate a 24 pin DIP socket for the EPROM (or EEPROM) -- 7 holes wide and 12 holes long. I use perf board with solder lands on it for the top (larger) piece of perf board and "bare" perf board for the smaller pieces. I run 20 small wires (appx 20 or 22 AWG solder coated bare copper wires) vertically through the stack of pieces of perf board. I use three of the small pieces of perf board to space the top (larger) piece of perf board above the parts below. I space the top piece of perf board (relative to the others) with an offset as necessary so that it will not interfere with the injection filter when the PL encoder/decoder is replaced in the radio. Once I have this arranged so that the adapter will "fit", I set aside the top piece (making note of its position) and glue the three small pieces of perf board (and the 20 wires) together with a small amount of epoxy glue. Don't let the epoxy glue run down on the wire ends that will end up being soldered into the PROM socket holes in the PL circuit board. At this point I leave the ends of the 16 wires stick out each end of the stack of perf board.

4.) Once the glue has cured I then hook up wires (I use 30 AWG "wire wrap" wire) to the top of the stack. These wires will later be connected to the EEPROM (or EPROM) socket. First I trim the 20 wires so that they are sticking out of the header by about 1/4 to 1/3 of an inch on the bottom end and about 1/4 inch on the top end. I use 30 AWG insulated solid wire ("wire wrap" wire or similar works great ) for the wiring. I connect one end of each wire to one of the 20 wires that are (at this point) sticking out of the top of the "header". Solder these wires as close as possible to the top piece of perf board. Later, I connect the other end of these wires to the 24 pin socket pins according to the table below. I make each of these wires long enough to reach any of the 24 pin socket pins.

5.) Now I put the larger piece of perf board on top of the assembly (placing it in the position noted in step 3) and push it down as close to the top of the stack as possible and secure it with more epoxy glue. When the exoxy has cured I trim the top of the header wires flush with the top of the stack and add the 24 pin DIP socket. This is soldered to the "lands" on the top piece of perf board - but could be glued if the "bare" type of perf board was used for the top piece. The last step is to hook up all the wires according to the table below. Note: Where a pin of the EEPROM / EPROM appears in more than one line on the table, use only the line which corresponds to the device you are using (i.e. 2804, 2816, 2716, 2732). Note that some wires go to two or more pins of the 24 pin socket.

6.) I double check and then triple check the wiring. First by visual inspection, then by putting a programmed EEPROM into the 24 pin socket and then putting the adapter into my PROM programmer. I then "read" the data from the PROM adapter into the programmer and verify that the data read matches what was programmed into the EEPROM.

7.) If everything checks out OK, I install the adapter into the Syntor PL circuit board and replace the circuit board into the radio.

Following are some pictures of a completed "home brew" Syntor PL - PROM EEPROM adapter.

A completed adater wired up for a 2716 type of EPROM

Bottom view of the completed adapter -- ready for testing and installation.

Bottom view of the same adapter -- from the other side.

End view of the completed adapter

The completed adapter installed into a Syntor PL encoder - decoder. NOTE: be sure that the adapter has enough clearance so that it doesn't interfere with (try to occupy the same space as) the receiver injection filter which passes through the oval hole just to the side of the adapter.

[Home]