RT4 potentiometer clean

This unit is the RT4 and RT5 system and is made by Magneti Marelli
Main differences between RT4 & RT5 - RT5 has Bluetooth Hands Free, faster Navigation calculation and on C4 & C4 Picasso only, USB ports and a High-Res screen.

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osx
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RT4 potentiometer clean

Post by osx »

Any ideas how to clean the volume potensiometer? Can't see any opening to using the cleaning spray I use for my HiFi equipement.

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Last edited by GiveMeABreak on 01 Sep 2020, 10:58, edited 1 time in total.
Reason: Moved to RT4 Section
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Re: RT4 potentiometer clean

Post by GiveMeABreak »

You'll just have to use electrical contact spray with a straw to get it under and inside where the track is I suspect, or try and solder on a replacement component.
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Re: RT4 potentiometer clean

Post by osx »

There is no gap anywhere to spray so was thinking of immersing it in some sort of cleaning solution (could use the contact spray) and give a few good spins. Not sure what replacement component as it doesn't have any markings and just measuring the impedance is not enough as it is not just a simple potentiometer (has also a switch function).
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Re: RT4 potentiometer clean

Post by GiveMeABreak »

There can be a build up of an oxidisation layer on these sometimes after a period of non-use, especially if you tend to use the steering mounted volume controls. One way to get it going is to rapidly jog it left and right for about 30 seconds or so, like a DJ on the decks, as that can remove the oxidised layer and get it going again.
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Re: RT4 potentiometer clean

Post by osx »

Interesting to see an nvidia GeForce chip in the RT4

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Re: RT4 potentiometer clean

Post by osx »

Next job is replacing the noisy fan. The connector is not the typical 3 pin but should work by soldering the cables.


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Re: RT4 potentiometer clean

Post by osx »

All jobs done
- potentiometer
- new cooling fan (found one from a northbridge heatsink - older PC enthusiasts will remember these!)
- SSD replaced the aging Toshiba hard drive

No I need to get the display to show actual tyre pressures

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Re: RT4 potentiometer clean

Post by GiveMeABreak »

You can't on the X7 - it does not show pressure values only the deflated / puncture warnings as the TPMS ECU does not provide that info.

Also be aware that your SSD is likely to start off fine and gradually crawl to a halt because of previously mentioned lack of Automotive UDMA 7 support which is SATA specs. The system used on these is IDE PATA interface. I've seen it happen countless times with others as TRIM is NOT supported and SSDs require this for efficient operation, or they will slow down over time.

You will get away with it for a while, but as the data area allocated for user addresses / route calculations is used up, it will run out of space to write to. SSDs have to clean the data that is marked for deletion before you can add new data onto it, and this process causes a slow down and consequently, the SSD speed will drops when it is writing data.

TRIM tells the operating system that certain data blocks are not required and deletes then to speed up SSD writing. But your Automotive OS has to support the TRIM function to do this and it is not supported on this operating system with PATA interface that uses the basic IDE command set.

It's another reason why I've covered it in my Navidrive NG4 Hard Disk replacement guide - that a UDMA6 (max) CF card is used as these use the same IDE commands as PATA.
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Re: RT4 potentiometer clean

Post by osx »

This is interesting because I can see tyre pressures in Diagbox. How can that be?

As for the SSD I think you are probably referring to the use of CF cards and not SSD's. If you use an SSD with internal background garbage collection (this works independently of trimming so not OS dependant) there is no issue. Don't forget that you are not using the SSD with an operating system with high read/write cycles.

A CF card will fail way before an SSD as they do not have any internal controlling mechanism for garbage collection.
Last edited by osx on 01 Sep 2020, 14:17, edited 1 time in total.
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Re: RT4 potentiometer clean

Post by GiveMeABreak »

I think it's to do with the data that is sent to the instrument cluster LCD (on my X7) and how it is interpreted. Your data seems to be the same but goes to the large multifunction screen on the RT* models. I'll look into this a bit further....

Appreciate that - but regardless TRIM is really needed for SSDs to operate correctly or they will slow down considerably over time. I've know people with this issue and they got fed up of removing the SSD, sticking into a PC, formatting and re-cloning the partitions and files over and over - so got rid of it and went the CF card route. I also initially tried an SSD but it was pitiful and got shot of it. Mine flies with a CF card and booting is almost instantaneous.
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Re: RT4 potentiometer clean

Post by osx »

Interesting read as I was not aware that Apple did not support TRIM. AFAIK TRIM is unnecessary with SSD's that use Sandforce controllers so it is likely that others had problems because they tried to use SSD's without internal garbage collection or Sandforce controller.

https://getprostorage.com/blog/ssd-garb ... 0efficient.
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Re: RT4 potentiometer clean

Post by Hell Razor5543 »

I can confirm that, if the SSD does not have the ability to 'manage' itself and the system it is in cannot perform those 'management' tasks, the SSD will not last long.

A few years ago one of our clients decided (as part of a company wide stores upgrade) to replace the HDDs in their tills with SSDs. The IT team, understanding the technical needs, went for SSDs that could perform the management tasks themselves. Unfortunately these were expensive, and so (despite the protestations of the IT team) cheaper 'dumb' SSDs were selected. As the till base units were developed before SSDs were available they cannot perform those management tasks, and within a year or so the SSDs were failing. We now are (whenever we get a call to replace an SSD for this client) are fitting the more powerful SSD (made by Crucial), and systems with these make of SSD are no letting them down.
Last edited by Hell Razor5543 on 01 Sep 2020, 18:07, edited 2 times in total.
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Re: RT4 potentiometer clean

Post by GiveMeABreak »

I've just checked the BSI and there are only 2 options - 'Absent' and 'Direct without display of pressures'.
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Re: RT4 potentiometer clean

Post by osx »

Where is the third option "Direct with display of pressures" :)

Can you see your tyre pressures in Diagbox?
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Re: RT4 potentiometer clean

Post by GiveMeABreak »

I can't remember, but have been nursing a racing pigeon that landed at hours today for a stopover so haven't had time to go and check. But I suspect that the BSIs on these are only designed to provide the default messages and symbols on these later systems - the older C5s had the actual pressures indicated.

I have a feeling it has something to do with the EU standards again :roll: - and having common warnings / messages on later systems.