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Yaesu FTDX 1200 Bad CAT Interface

Discussion in 'Radio Circuits, Repair & Performance' started by KG5NII, Oct 22, 2017.

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  1. KG5NII

    KG5NII Ham Member QRZ Page

    The CAT interface on my FTDX 1200 has stopped working. The CAT interface electronics is located on the CNTL PCB assy and after doing some measurements I do believe the problem appears to be a bad ADM3202 RS-232 Line Driver/Receiver IC.

    Here is the schematic of the CAT interface:


    Simple circuit. All the voltage measurements except for Vcc are horribly off as denoted by the annotations in RED. The voltages are measured with nothing connected to the DB-9 connector (J3004). The annotations in PURPLE are from the ADM3202 datasheet. I should be seeing about 6.4V at V+ and -6 .4V at V-. To those of you who have worked with chips like this, do you agree with my conclusion the IC is fried? The 1 uF caps check OK.

    As can be seen here:


    The IC is a 16 pin TSSOP and is quite small. I really do not have the equipment or the eye sight to replace this chip so my thought is to find someone who can replace the chip and send the CNTL PCB to them for component replacement. This way I will not have to incur the cost and risk of shipping the entire rig. This is the best alternative I can come up with but that still leaves me with the problem of finding someone who can and is willing to replace the chip. The above layout is not to scale and it is much larger than it actually is on the PCB. Wow! These are some really small parts! I've worked with SMD before but not components this small. I'd really like to get my CAT interface functional again and it's driving me insane knowing it's not working. I think its pretty obvious the chip is fried but please do offer your own opinion.

  2. KA9JLM

    KA9JLM Ham Member QRZ Page

    I does look like the 200 kHz charge pump is not working.

    Good Luck.
  3. KB1YFD

    KB1YFD Ham Member QRZ Page

    If you need someone to fix the board for you, I am willing to do it for free.
    It might be just a bad solder joint, check it out with a jewelers loop.

    John KB1YFD
    KA9JLM likes this.
  4. KG5NII

    KG5NII Ham Member QRZ Page

    This is a follow up post to the topic of a bad Yaesu FTDX-1200 CAT interface. It was determined the ADM3202 RS-232 Line Driver/Receiver IC was indeed bad. Now there were several possibilities on the repair and upon reflection I did not put much faith in myself to be able to effect the repair. Sure I diagnosed the problem but repairing it was another matter entirely due to the small size of the 16 pin TSSOP chip that needed replaced. Well guess what? The defectdive ADM3202 IC is still in the circuit. As I stated in the thread, I was faced with just sending the PCB in to someone and let them replace the chip. Then I realized there were several methods I could follow that would allow for the removal of the chip. One solution would have been to use a product called Chip Quik:

    The prices for Chip Quik range from about $15.00 on up. Not a bad option.

    The second option would be deadbug a new chip on top of the old one after lifting the VCC leg off the pad of the old chip. I don't like this option as too many negative interaction possibilities exist.

    The third option would be to buy a hot air rework station with decent ones going for about $50. Next there is the cost of the flux and solder paste to consider along with tweezers and possibly a vacuum pen. Total coast $75 - $100 or as much as $150 if one considered purchasing a magnifier or a usb microscope. The problem with this option is I don't work with SMD that much so while I think having the hot air soldering station and the microscope/magnifier would be a handy addition to my lab workbench, I can think of other things far more useful to spend my money on. So I considered this not a very good option for my particular situation.

    To be truthful, I almost talked myself into buying the hot air station and the usb microscope. I did end up getting the USB microscope simply because I need something like this. My eye sight is just horrible:


    So what did I do to get my CAT interface working again? In the spirit of amateur radio I adapted, persevered and overcame (Thank you USMC!). In my opinion Yaesu should have included a USB port in the radio. I consider this an almost unacceptable omission. On my work bench I happen to have an Adafruit FT232H USB to serial converter + SPI + I2C + JTAG + GPIO breakout. So in it's simplest form the board will allow one to interface USB serially to either a 5v or 3.2v circuit. Now there are much simpler boards that will do the same thing for 1/3 of the price but I happened to have one of these to spare so I put it in my rig.

    YES it's overkill but I don't care! Now it just so happens on rear of the FTDX-1200 between the CAT interface DB9 and the u-Tune jack is a hole in the chassis that Yaesu was nice enough to already drill out. It's just covered up with tape! So taking a drill bit the size of the hole already in the chassis and drilling through the tape will have a nice little opening just the perfect size to allow a micro USB connector through! But the challenge was how to mount the breakout pcb and have it aligned with the hole? It just so happens the rig's built in tuner bolts in right above the CNTL pcb (which has the CAT interface electronics). The tuner is basically enclosed in a tin box with the bottom of it having two conveniently placed threaded inset flush mounted studs. I cut a piece of double sided copper clad board along with some plexiglass and used this to mount the breakout in such a way that it is almost perfectly aligned with the hole in the chassis. Granted it is inset quite a bit into the rig but one can still with a little effort plug the micro usb connector into the board with out too much trouble.

    This image shows the connections:

    I used small 4 conductor ribbon cable cut to size. The connections require a rather small soldering iron tip. Be extremely careful to not apply too much heat and too much force to the CNTL pcb!!!. Be sure to check for shorts with your ohm meter when done! I removed L3001 so as to keep 3.2v vcc off Q3002. Not shown in the graphic is the FT232H ground connection. Make sure the GND pin on the breakout board is grounded to the FTDX-1200's chassis. In my situation I simply had to solder a small wire from the GND pin to the copper clad board it was mounted on since it is grounded to the antenna tuner assy. With the connections shown above full RTS/CTS hardware flow control is fully supported, but one could get by with just connecting D0 and D1 and thus forgo RTS/CTS flow control.

    This particular breakout will support any baud rate you throw at it. The FTDX-1200 only supports up to 38400 baud so the breakout will support this with absolute ease. Now to access the CAT interface, simply plug your computer USB into the microUSB port in the back of the rig. If you are running Linux like I am ensure your running kernel has USB FTDI Single Port Serial Driver either as built in or as a module in your kernels configuration under:

    For Windows or Mac Install the FTDI drivers directly from FTDI Drivers support page.

    The end result is I am now glad that I procrastinated on repairing the CAT interface giving me time to clearly think out my options. The end result is the cheapest solution and now the rig has the built in USB support that it should have had designed in to begin with. Note to Yaesu: Get a finger out and build USB into your radios. No excuse not to do this.

    Please note this document is not meant to be an instructional on how to build USB into your FTDX-1200!!! I was not able to take photos of my implementation, but I believe I have adequately described the process one needs to go through in order to have functional built in USB in their FTDX-1200. The same principals that apply to the FTDX-1200 can apply to other rigs with CAT interfaces, however, of course the manufacturer implementation will be completely different than what is described here and so you are completely on your own.

    Yaesu FTDX-1200 documents:

    FTDX-1200 Technical Supplement

    FTDX-1200 CAT Operation Reference Manual
    FTDX-1200 Operating Manual

    I'd be happy to answer any questions to anyone who is interested in adding this to their rig.

    Ron KG5NII

    KC4UMO and KA9JLM like this.

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