Batboard

Somewhere I saw a lot of complaining about the current (2010) Ebay Ribless cables. (KAWAMALL, etc.) I previously bought an XTS300 Ribless cable and a RIB box..both worked fine for their radio types but the XTS5000/XTS2500 cable failed miserably so I took it apart and did some poking around..(Boards made by Maxton ..They are in China..They have a website..They make MOTOROLA cables..BUT they do not list this cable )
The MAX202 chip was blown so I ordered several replacements (along with the DS2433). When I took the old chip off I drew a schematic and replaced the .1uf caps with 10uf Tantalum (Observe Polarity). (I don't know if the larger caps made a difference...but they were free). While I was drawing the schematic I questioned why the 7.5 Vpp from the XTS had been rerouted directly to the MAX202. (pin 16) Some of the MAX232 series aren't too particular about supply voltages..The MAX202 REQUIRES 5V +/- 5%... 7.5 volts is outside that range..ergo the blown chip..
There is also a 75L05 regulator onboard..Current chips seem to work down to 1.7V dropout but I am not sure how current these chips are..There is also a blocking diode in line with the original supply line.. I skipped this and wired the 7.5V directly into the 78L05 (right pin)..If these are ST chips then 7.5 v will be adequate...but maybe they are older and thus the wiring change.
The case at the db9 is held together with 4 pins...The plate over the pins at the radio end will also pry off. 2 pins (Near the top) on the cable end....Pry CAREFULLY /Shallow and the cases will come apart.. The boards at both end are clearly marked and the push pins at the radio are thru hole so they won't pop off if mishandled. A microscope will help..DO NOT overheat the boards...the pads WILL lift. CUT the pins on the MAX202..then unsolder the pins
The cable does work well now.
I tried just adding a DS2433 to a USB cable for the XTS2500 ( CTS HARD grounded) but had no success.. I may not have tried hard enough or it may actually need code stored on the chip...Haven't looked at it again.
N7BMG

great information, but you know after banging my head against the desk with these knock off POS'es, for the hassle you can save risking your radios and buy a REAL OEM serial cable from a couple of Ebay sellers for 50 bucks. Why go through all the trouble and worry about turning your XTS5K into a paperweight using these cheaply built pieces of garbage when you can have the real thing for not much more? They're built better and they work right the first time and every time.

The electronics are not the only place that corners are cut, what about the cable itself? The wire on the A/M cables is very crappy and prone to breakage. The pogo pins used in the connectors have very cheap springs in them and I have seen a cable that was only used a few times that had one of the pins gone bad already. Then there is the construction, I have a Maxton board in my hand right now and wires are stripped back far enough that contact with the TXD, and GND could easily happen. This cable was giving to me by a friend who used it about a dozen times and it failed due to the MAX202 had lifted off the board. The solder job did not look that good, and from the over voltage you mention it could have been enough heat generated to allow the IC to come loose.

Well I have and on occasion use an A/M cable on some Icom gear I try my best to discourage use on the Astro, or Astro25 series of radios. The Icom does not care if you unplug it when programming, but for a Moto that can yield you a bricked radio. An OEM cable cost much less than a trip to the depot. And as Erik pointed out, the OEM RS 232 cables are at about $50.00 now.

Thanks for posting your findings just the same, I may end up checking on upgrading the Icom cable I have.

Jim