MicroHacker Forum

I guess most of you know, but just to provide complete instruction and explaination for this issue.

First, the symptoms and diagnose:

• The unit restarts itself from time to time, but music continues to play
• The home address can't be stored anymore
• The unit does not turn on when pushing the ON tipper
• It draws current (approx. 100-200 mA) even if not working and car is locked. If car is not moved for some days it could also empty the battery
• The unit can be revoked to life by heating up the mainboard, especially the RAM chips, until next powerloss. Do not just put a hairdryer or heatgun into the unit, beware of damaging parts!
• The units mostly fails on cold days with temperatures below zero degree celcius.

Next, for the cause:
The units,all use the same type of SDRAM, two Micron "46V64M8-6T IT F" chips. There was a wide series of chips having a failure in the mask, causing them to fail after some years. They get temperature sensitive, the colder the more they fail.

If you remove the board from the case, put 12V on pin 15 and GND on 12: heat up the RAM chips with an SMD hotair gun (80-100°C) for some seconds, you should see that current first drops and then rise up to 600-800 mA. If you see this current draw, the unit has bootet successfully and you know the RAMs are faulty.


Finally, the solution:
Replace both RAMs
Keep in mind that usually only chip dies, but the are made in series and the other is likely to fail short after the first one. So be professionell and always replace both chips. Also do not use compatible ones from other brands, and if, only use automotive certified ones. Using chips from old PC RAM bars may work in the first, but they will fail as soon as it gets colder. Also timing is very crutial and automotive chips are more selected and tested for low tolerance.

Where to get those damned chips and what about the loads of Chinese offers?

Beware that 99% of the chip offered on the Chinese marketplaces are fake cheap copies! Even if they should work, they got so high tolerances that most of them would'nt even boot the unit, nor they keep it up for long. If you ever see a photo, ensure the marked labels are there and exactly the same as in the picture: The first good indicator is the Micron logo itself (6). There are only two official versions of them: If it looks other or only similar, it's a fake.

Next, look for the right type, especially the "IT F" signature (3). If it's not there, it's not automotive and will fail.

Go4IT wrote: ↑20 Mar 2019, 06:05 I can only warn you to buy those on the chinese marketplaces, because 99% of them are fake and cheap copies.
Next, look for the right type, especially the "IT F" signature (3). If it's not there, it's not automotive and will fail.

do you mean not to buy

Thanks for pointing out my bad English. I've changed the context of the sentence to be more clear

Hello!!!

I bou a damaged FX to try to repair, is a FX from a mondeo. my purpose is replace both ram memory to practice to use my new soldering station and microscope.
If the unit work, i used this to try experiments, firs step is put firmware from a kuga unit. if the unit don work, i think save it to spare parts.

my first steep is remove a rm memory, y desolded one, and is very easy with hot air, next steep is remove the second ram.

i waiting to receive new memory to put but in some days or weeks i receive.

when i end my work with this "training unit" i xplain my results here.

Hey folks, how you doing?!
I recently found another issue regarding of non-booting FX (and may also true for NX and MCA). I got an repair help request with the typical failure "draws battery low and won't start any more". I expected it to be the well known RAM failure. As the device arrived i was surprised that it was an so called "X-Part", labled at the side of the radio. This means the device was replaced by Ford in a warranty issue.

As i opened it, i found the RAMs where already changed to current genuine ones, i assume by Bosch. The Device only draws about 40 mA and applying heat/cold to the RAMs didn't change anything. So i replaced them, just in case. But again no bootup, no change.

I then tried to download the flash to may clone it over to a working board if i can't fix this one. But i can't even connect via JTAG, which would normally work, even without RAMs soldered in. So i take a closer look and found a strange brown area above one of the power regulators and a small silver solder ball above.
The regulator (an LTC 3407) creates the voltages for the OMAP and the RAMs and Flash. I measured them but they are only a few millivolts. So i changed the regulator chip and TATAAAA!! It's booting again

Changing this little bastard is a bit pain, because it has a massive GND plate on the lower side of the chip. Need a lot of heat.

And a again, another successfull revoke to live today!

I had a unit not starting anymore. First, i checked the powerconsumption - was about 120mA after applying 14V and goes down to 25mA after a few seconds and then down to 5mA after another few. First i suspected the RAMs but they won't react on heat. Even after changing the RAM chips, now change. I then checked the LDO (LTC3407, like in the article above) and found that one regulator work but the other one not (the LTC has two independant LDOs in one chip), so i constantly have 3,3V as input and 2,5V as output but not the 1,6V. The LDO controls the runstate of each LDO by an input port (RUN1 and RUN2) which must be HIGH (3,3V) to enable the LDO. One input was permantently GND. I then traced this input to a voltage monitor chip MAX834 (SMD label "AAAX") which is positioned here (yellow arrow to part (23)) on the board: The chip checkes if the input voltage (which comes directly from battery input, protected by a 5,6V zener and some resistors) is within a given range (set with resistor divider) and toggles an output pin. In the given configuration, if the input voltage would drop under 9V the chips sets it's output to LOW (GND). If it goes above to HIGH (3,3V). If the voltage once drops and rise again, the chip remain at LOW until fully powered down. The output pin was held HIGH via a resistor from 3,3V. Those 3,3V comes from the big voltage regulator around part (10) and seems to be there at any time, without any condition. Nearly all other regulators and parts are switched by some logic and of course the OMAP and RU-Processor. One part of the logic is the above voltage monitor.

I desoldered the MAX834 in the expectation that if it is wrongly holding the output pin to low, the system would never start. And BINGO! after i applied power the system boots up like a charm
Soldering this part is fiddly, because you are near to the big caps and hotair could easily damage them. I put some capton-type onto the lower side of the caps to protect them. It works, but be carefull!

I then fetched one from an mainboard where i know it's working and placed it onto the faulty board:
This worked, the system runs again! So another possible issue was found (whatever killed this chip...).

Hello:

Today i replace the both Ram memory in a Fx of a friend job, and now works fine!

Thanks to Go4IT to help me in another Fx to replace the memory, now i reply the same steps with good results!
I take some pictures of the process:

Pass the wire to pull up the ram Removing the ram Ram Removed New Memory installed The Fx Wirking

Put it in freezer, in a bag, after you changed the RAMs and let it cood down to room temperature, for 5 minutes then get it out and apply power to it.
It's a good test to see if all the contacts are good and also if the RAMs are good too.

DGAlexandru wrote: ↑03 Dec 2019, 10:29 Put it in freezer, in a bag, after you changed the RAMs and let it cood down to room temperature, for 5 minutes then get it out and apply power to it.
It's a good test to see if all the contacts are good and also if the RAMs are good too.

I try it and work fine after remove from freezer, thanks!!

oscarboiro wrote: ↑03 Dec 2019, 11:01

DGAlexandru wrote: ↑03 Dec 2019, 10:29 Put it in freezer, in a bag, after you changed the RAMs and let it cood down to room temperature, for 5 minutes then get it out and apply power to it.
It's a good test to see if all the contacts are good and also if the RAMs are good too.

I try it and work fine after remove from freezer, thanks!!

hi i have a NX with the Ram problem but i have not been lucky to find any good chips anyone have any to sell or point me in the right direction