Hello. you can make a flash cable by yourself. only need a standard usb cable and a 12 v dc supply. Dtr has 17 pin at bottom connector (3 and 14 ); just connect on 14 pin side like following: black usb cable to gnd, red one to pin 3, green to pin 1, white to pin 2, and 12v dc to pin 12. Once you do it, just plug usb on pc, battery to radio and it is recognized as usb device by firmware software. Hope this works for you
Amazing information - I’m not sure how you managed to figure this out, but thank you so much! If this works we should get some pictures showing the wiring on the DTR connector.
So, has anyone else tried this out? Confirmed working?
Just for clarification, the pin numbers above are for the 14-pin section. If we’re to believe the information below, the 1st pin in the 14-pin section is called pin #4.
So, based on the diagram above, me ripping apart an NNTN4049A USB -> Moto cable, and the information you gave, this is the pinout:
Pin 1&3: Black (Gnd)
Pin 4: Green (D-)
Pin 5: White (D+)
Pin 6: Red (+5v)
Pin 15: +12vdc
Also, the shield is connected to the internal metal shield around the connector.
Note that the v60 connector is not actually the correct connector. The v60 connector uses a top locking mechanism, while the DTR uses a side lock. Also the block between pins 3 and 4 is bigger on the v60 connector and has to be cut off to work with the DTR.
I have built this cable (by Frankenstein-ing a NNTN4049A cable I had) and can verify that it does in fact work! 
Now if someone can find a source for the proper Moto 17-pin DTR connector…
So pins 1&3 are both fed back to USB ground?
Pin 15 is getting +12V, but there’s no -12V? USB ground is enough?
Yes, in my case. No idea if Pin 3 needs to be connected to ground, but it already was in the cable I butchered so I left it.
Pin 15 is getting +12V, but there’s no -12V? USB ground is enough?
The ground of your 12vdc supply connects to Pin 1&3, same as the black USB wire. There is no -12vdc.
OK, so pins 1&3 get USB ground as well as PSU 12V ground.
Serial cables are still around - maybe one of them just needs to sacrifice itself for the cause.
Not sure if the Serial cables would have all the needed wires connected or not. The USB cable I butchered only had the 4 USB wires. Also, the connectors are glued together - pretty much destroyed the connector taking it apart. Additionally, like to do it on the cheap and the serial cables can still be expensive.
But, it’s probably a proprietary connector only made for Motorola anyway so there may be no choice…
That very well could be. A multimeter should be able to tell us what pins are tied back to the serial I suppose.
Also, for as many times as it would be needed to work, creatively modifying the V60 connector isn’t unreasonable. Even if you have to stand there and hold the v60 connector in the dtr jack while it flashed. I mean, how many radios will one guy flash over his lifetime?
Over 100 myself so far, but then I have the flash cable. 
But you’re absolutely right that most people would only need to use a few times. I’m glad that I was able to give building one it a try, so hopefully others can give it a try too.
The Motorola NKN6559A cable (often called “Nextel i830/i205/i305/i530/i730 USB Data Cable”) looks like it might have the right end or close to the right end…
Let me know how you make out with yours!
OK, I’ll check out that cable. I’d rather butcher a $5.99 cable than a $30 or whatever.
I’ll post results after. Wonder how long it will take to get here…
Did you ever get your cable and try this?
I have now tested this using a DC-DC converter the same way (I expect) the original MOTO cable does. Works perfectly and no external 12v supply needed!
Pretty pleased with this!
I have not had a chance to try this out yet. Barely finding the time to sleep lately 
I can say that the cable end fit into the dtr perfectly so as long as there are no wiring surprises inside the cable it should be a good donor.
The NKN6559A cable I linked to earlier? If so, cool, as I’ve ordered one as well to test. If all goes well, I’ll post some instructions and pics on how to make your own cable including the DC-DC converter.
Very interested to find a diagram of the custom made cable.
I still plan to take some pictures as I make the next one as soon as life gets out of the way. 
Just to follow up, I actually scored a flash cable from ebay. Flashing was successful…
So, has any enterprising entrepreneur (are there any other kinds) decided to start making these for other, less capable hands?
In other words, I suck at rewiring stuff. But have a pair of 620’s I’d love to retrain to talk to my 550’s.
Dave
I can make them, but the cost of the parts and labour to make it worth selling would be more than anyone would want to pay.
In other words, I suck at rewiring stuff. But have a pair of 620’s I’d love to retrain to talk to my 550’s.
Why do you think flashing your radios will get these two devices to play nice?
My impression is that the 620 uses different frequencies than the 410/550/650 as it is designed for sale in other countries. However, I have yet to find any real specifications that show the differences between the two series.