Yaesu: FTM-500DR - American model PCB differences for MARS mod

[eraser928]

Thank you for this thread!

The mod worked on the 4E board (bought May 2024 at DX Engineering) by removing the tiny diode in the pink circle in the OP's picture. We did not try the shorting resistor method.

 

[KE9ARJ]

I preformed the mod on my 500dr with a serial number beginning with 4F. The board appeared to have a similar layout to the 4D. I simple removed the smaller diode, nothing fancy, just snipped it out and verified that the traces were no longer connected with any remaining solder. After reassembly the radio started up in its factory form. I could not read from the SD card. Simply format your SD card (save your data else where first) and write to the SD from the radio menu. I then popped out the SD card and placed it in the PC and saved my previous settings on the card. The radio was able to read from the card at this point. Very simple mod. All is working as it was prior to modding with the added TX range.

 

[AK9R]

I preformed the mod on my 500dr with a serial number beginning with 4F. The board appeared to have a similar layout to the 4D.

The first two digits in a Yaesu serial number indicate the year and month of manufacture.

4 indicates 2024. The month code starts with C for January, so D is February and F is April.

 

[pramodn]

Hi All, Pramod (VU3UZJ) here. I recently purchased a Yaesu FTM500DR(4H) from Japan and attempted the MARS mod. Unfortunately, I removed the 0-ohm resistor (highlighted in the pink circle) without seeing this thread beforehand, and now my TX is locked. Upon further inspection, I noticed a short in the area highlighted in the orange circle. I would appreciate any guidance on whether any additional changes are required to unlock the TX for use outside the Ham bands.

 

[KD7RJC]

Hi All, Pramod (VU3UZJ) here. I recently purchased a Yaesu FTM500DR(4H) from Japan and attempted the MARS mod. Unfortunately, I removed the 0-ohm resistor (highlighted in the pink circle) without seeing this thread beforehand, and now my TX is locked. Upon further inspection, I noticed a short in the area highlighted in the orange circle. I would appreciate any guidance on whether any additional changes are required to unlock the TX for use outside the Ham bands.

I thought there was a button combination for resetting after modding but it's been several months and I can't remember with certainly.

 

[pramodn]

I thought there was a button combination for resetting after modding but it's been several months and I can't remember with certainly.

Could you please assist me if you recall the button combination? I attempted to restore my radio to factory default settings using menu option number 127. However I am unable to TX outside ham band.

 

[WRMorrison74]

I've got a pair of these radios that I'm getting ready to perform the modification on, and I thought I'd add my info for data collection purposes. My first radio was purchased from DX Engineering back in Nov 2023, and it has a SN prefix of 3I (July 2023). It has the "old style" board with a few other differences (an extra cap, etc).

The newer radio was purchased at a hamfest a few weeks ago (Jan 18, 2023) and has a SN prefix of 4K (Sept 2024) and has the "new style" board.

I don't have much of a choice on the old style board but to remove the tiny resistor, but at least I can work with the larger resistor on the new radio. I won't be doing any of these modifications as I don't trust myself or my equipment; I'll be looking for someone else locally.

 

[KD7RJC]

I've got a pair of these radios that I'm getting ready to perform the modification on, and I thought I'd add my info for data collection purposes. My first radio was purchased from DX Engineering back in Nov 2023, and it has a SN prefix of 3I (July 2023). It has the "old style" board with a few other differences (an extra cap, etc).

The newer radio was purchased at a hamfest a few weeks ago (Jan 18, 2023) and has a SN prefix of 4K (Sept 2024) and has the "new style" board.

I don't have much of a choice on the old style board but to remove the tiny resistor, but at least I can work with the larger resistor on the new radio. I won't be doing any of these modifications as I don't trust myself or my equipment; I'll be looking for someone else locally.

I'm curious about that extra capacitor. Can you get a photo of where it's attached? It seems a little unusual to be installed that way.

 

[SA4MDN]

Could you please assist me if you recall the button combination? I attempted to restore my radio to factory default settings using menu option number 127. However I am unable to TX outside ham band.

Why would you want to?

 

[WRMorrison74]

I'm curious about that extra capacitor. Can you get a photo of where it's attached? It seems a little unusual to be installed that way.

The two leads circled are soldered together and you can see where the wire goes. Not sure what the R47 resistor is connected to under the glue.

I've also attached pics of the only other difference I've noticed.