User:Moose

There are some other variants of these that have the same no power failure. All of the NX-5000 series radios have nearly the same design. Even the skews named tk-5930F have different software licenses and warranties but use the exact same replacement board as the NX-5900K. The high power models NX-5700HF for example look different but have basically the same circuit design and therefore the same failures.

By far the most common issue is ic2 in the NX-5000's and ic22 on the NX-3000's. There are also some other common causes for no power on, I will get to those later.

Chances are if you have one of these common models die, this texas instruments power management chip is at fault. The 3000 series units use Kenwood part msp430g25kgpa, the 5000 series use msp430g25kgca. I think the 3000 series version may just have better specs in some small way. They can be swapped for each other with no issue in my experience. A little trick after swapping one of these chips is to enter test mode and hit "control, shift, m" and then you will update the firmware that runs on this ic. I remember searching the data sheets for this part and I found that the difference between the kgpa and kgca version was not significant. I think dealers can even get the correct part from kenwood directly.

The 3000 series also has another common failure and 90% of the time if it's not a power management chip its a bad crystal near the bga's "x401". You can check this crystal by verifying that pin 4 has 3.3v and probing pin 3 with your scope. If you don't have a nice clean 19.2mhz on pin 3 or your voltage on pin 4 is dipped you got a problem. Failures of this tcxo include a short, no output, incorrect output frequency, and low amplitude output.

To troubleshoot the power management chip I first 1. pop the cover off the top of the unit. 2. pop the control head off the front. leave it plugged in I just pop it off to verify that the ribbon cables are connected properly. 3. Hook up ignition sense to 12v as well, just eliminate the variable. On the 3000 series ignition sense is pin 2 of the 15pin d-sub. 4. At this point (with 12 power on) hold the power button for like 8 seconds to make sure the unit is in fact dead and not just turned off. Sounds silly but plenty of people make this mistake. They forget they programmed ignition sense or simply had the unit shut off. A lot of dead units are just a not correctly seated control head cable. Or a control head that is not plugged in. 5. After confirming the unit is dead check the fuses. There are 3 up near where the power cable comes in. 6. Here is the good stuff: now after eliminating all the dumb stuff check for 1.2v on...

I am not done with this page, I will finish it in the future... I would like to add pictures and schematics but do not currently have them on this computer.