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-   -   MK4 capacitor value, need a favor! (https://xoutpost.com/electronics/navigation-system/79217-mk4-capacitor-value-need-favor.html)

roger8wilco 02-08-2011 11:24 AM
MK4 capacitor value, need a favor!
 
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Working on fixing my MK4... found a bad cap but it has no markings with its value.. anyone have an MK4 apart with a cap meter???

Attached is a pic of the exact cap i need a value for.. thanks!

and i stole the pic from an earlier post, i know :nanana:

big bob 02-08-2011 03:42 PM
If you don't find the value that looks like an RC filter for smoothing. Just fit the biggest 16V or 25V 0805 cap you can find. Should be fine.

R2D2 02-09-2011 10:33 AM
Measures 200nF on my meter, so is probably a 220nF. Looks more like an 0603 size to me though, but as said fit the 25v type because theres no way of knowing the voltage that sits across it...

MURATA|GRM188R71E224KA88D|CAPACITOR, 0603, X7R, 25V, 220NF | Farnell

roger8wilco 02-09-2011 09:25 PM
well, i pull a similar cap off a hard drive that was a couple uF... didnt fix the issue but at didnt make it worse either!

the unit turns off when the car turns off (no 60 sec to sleep) and doesnt save any nav settings unless i hold the eject button down.. a guy at work suggested using a cap at the eject line big enough to hold power for 60 sec or maybe run a lil circuit with a transistor and smaller cap...

I havent verified, but I think everything gets saved if after you turn off the car, hold the eject down for a minute.. if so, the above idea could be a potential fix..

R2D2 02-10-2011 04:51 AM
My nav turns off immediately when i turn the ignition off as well. Is this not meant to happen?
Isnt there a lithium battery on the nav mainboard which retains all the settings? Couldnt this be the problem?

roger8wilco 02-10-2011 10:29 PM
it turns off the screen but the nav computer should stay on for 60 sec afterwards..
no li-ion battery that i know, dont see it anywhere on the board

R2D2 02-11-2011 04:35 AM
Quote:
Originally Posted by roger8wilco (Post 803706)
well, i pull a similar cap off a hard drive that was a couple uF... didnt fix the issue but at didnt make it worse either!
If that capacitor is part of a filter circuit, then youll want to replace it with something of the same value or it will mess up the frequency that its filtering. Also, are you measuring a short across the capacitor and therefore assuming that its a problem with that component? If so, the short may not necessarily be across the cap, rather somewhere else that sits parallel to the capacitor.

Quote:
Originally Posted by roger8wilco (Post 804056)
it turns off the screen but the nav computer should stay on for 60 sec afterwards..
no li-ion battery that i know, dont see it anywhere on the board
The nav must retain its memory via the power coming in through the plugs in that case.

Bombolo 03-07-2011 05:56 PM
Quote:
Originally Posted by R2D2 (Post 804115)
The nav must retain its memory via the power coming in through the plugs in that case.
Sorry, but the mk4 is working not this way. The unit has permanent power supply, 12V +-, without ignition. But the unit does not forget the last position not because of the permanent power supply.
After you turn off the ignition, a saving procedure is started. The unit saves the actual datas to non-volatile memory. If there are no IBUS traffic, after the saving procedure the unit goes to sleep, at this point the red LED turns off. If you take out the unit from the car, no matter, the unit remains the saved datas even after 1 year, because the datas are in memory.
The broken mk4 you mentioned, has a defect power part inside, if you turn off the ignition, there are no saving procedure, the unit immediately stops. Therefore you have always the same, previously stored position, destination, settings, what was saved in the past, when the unit worked well.
The unit must wake up if:
- ignition is on, or
- ibus traffic detected (eg. door, trunk opening), or
- eject button is pushed

The ibus traffic monitoring part is defective, so if there are no ignition, and eject button is not pushed, the unit stops without saving tha datas.

R2D2 03-08-2011 04:20 AM
Quote:
Originally Posted by Bombolo (Post 809990)
Sorry, but the mk4 is working not this way. The unit has permanent power supply, 12V +-, without ignition. But the unit does not forget the last position not because of the permanent power supply.
After you turn off the ignition, a saving procedure is started. The unit saves the actual datas to non-volatile memory. If there are no IBUS traffic, after the saving procedure the unit goes to sleep, at this point the red LED turns off. If you take out the unit from the car, no matter, the unit remains the saved datas even after 1 year, because the datas are in memory.
The broken mk4 you mentioned, has a defect power part inside, if you turn off the ignition, there are no saving procedure, the unit immediately stops. Therefore you have always the same, previously stored position, destination, settings, what was saved in the past, when the unit worked well.
The unit must wake up if:
- ignition is on, or
- ibus traffic detected (eg. door, trunk opening), or
- eject button is pushed

The ibus traffic monitoring part is defective, so if there are no ignition, and eject button is not pushed, the unit stops without saving tha datas.
Interesting. I wondered why my custom OS was saved when i removed my nav a few months ago. I was expecting to have to reinstall it.

Great answer.

Bombolo 03-08-2011 06:46 AM
Quote:
Originally Posted by R2D2 (Post 810123)
Interesting. I wondered why my custom OS was saved when i removed my nav a few months ago. I was expecting to have to reinstall it.
Great answer.
The OS is not saved during the saving procedure, only the user data. The OS is saved during the software update, and you can update the OS even an mk4 with the mentioned power supply problem.

In case of MK3 the power supply problem can be deadly. The MK3 saves critical datas during the saving procedure, and if the powers supply breaks during the saving procedure, even the OS part can be damaged, then the unit cannot boot and OS cannot be updated, black screen and no red LED. The only solution is flashing the unit.
Therefore it is very important to wait the MK3 unit go to sleep, before unplug the power supply (blue connector) or car battery.


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