I added a heatsink to my 2004 CEM CPU

[djrichard]

Withstanding that, I'm thinking of giving up and working directly with xemodex . I can see they add the heat sinks and some kind of rubber proofing on top of the circuit board. Anything else they do to the CEMs to rehab them?

This part answered here: http://xemodex.com/us/product/centra...0657629-00-22/

THERMAL COOLING UPGRADE

All CEM’s have a heat dissipating sink installed directly on the MCU. This upgrade will ensure reliable processor operation during hot summer months.

COMPLETELY REWORKED PCB

All internal circuit boards are tested at the component level. Any known prone to failure parts that are close to the maximum tolerance are automatically replaced.

PCB CONFORMAL COATING UPGRADE

The circuit board is coated with conformal coating to help prevent damage to the components in the event of water intrusion.

[Willy]

Digital systems create lots of broadband noise.

They do, but unless th noise is broadcasted, not much harm is to be expected.
This could be the case for the transmission, the wiring acting as antenna's.
But since twsisted pairs are used, the wiring probably won't cause much EMI either.

[djrichard]

In my case, I added the heat sink and the problem occurred again. So I'm curious, should I put a heatsink on the 2nd chip inside the metal-ringed area as well?

I'm likely to send this into xemodex anyways, but I did a little leg work, so just wanted to report what I found.

The 2nd chip needs a heat-sink roughly 25x12mm. I say roughly because it's hard to measure with the metal protector abutting it. And 25x12mm is hard to find. Best I've seen so far is http://www.digikey.com/product-detai...1054-ND/340350 which is 10.5x19mm, making it a little bit smaller than the surface area of the chip.

xemodex seems to have found one that fits better based on their video. Of course, they've also removed the entire metal protector ringing the CPUs too, which would help with air flow. I'd have to use a soldering gun to do that myself and I don't trust myself enough to do that.

[djrichard]

Well pulled the plug and ordered the following:

• http://www.digikey.com/product-detail/en/0/345-1054-ND (a smaller heatsink for the 2nd chip as mentioned above)
• http://www.digikey.com/product-detail/en/0/1168-2057-ND (some double sided tape to adhere the heatsink to the chip)
• http://www.digikey.com/product-detail/en/0/259-1398-ND (a 40mm fan to blow air over the chips)
• http://www.amazon.com/Littelfuse-FHA.../dp/B0002BGELQ (a fuse tap to power the fan)

Note about the 40mm fan. The holes at the corner of the fan are the same size as the holes on the exterior CEM surface. But they don't exactly align. So maybe a different size fan (30mm?) might get better alignment. Even so, I was able to get them align enough that I just used twist ties to secure the fan onto the exterior portion of the CEM, through the holes of each. After I twist tied the fan onto the exterior portion of the CEM, I slid the interior unit in. There's not a lot of room between the interior surface and the exterior surface, but I was able to jimmy it in.

I'll report back if the problem recurs again.

[Boneslb9]

Well pulled the plug and ordered the following:

• http://www.digikey.com/product-detail/en/0/345-1054-ND (a smaller heatsink for the 2nd chip as mentioned above)
• http://www.digikey.com/product-detail/en/0/1168-2057-ND (some double sided tape to adhere the heatsink to the chip)
• http://www.digikey.com/product-detail/en/0/259-1398-ND (a 40mm fan to blow air over the chips)
• http://www.amazon.com/Littelfuse-FHA.../dp/B0002BGELQ (a fuse tap to power the fan)

Note about the 40mm fan. The holes at the corner of the fan are the same size as the holes on the exterior CEM surface. But they don't exactly align. So maybe a different size fan (30mm?) might get better alignment. Even so, I was able to get them align enough that I just used twist ties to secure the fan onto the exterior portion of the CEM, through the holes of each. After I twist tied the fan onto the exterior portion of the CEM, I slid the interior unit in. There's not a lot of room between the interior surface and the exterior surface, but I was able to jimmy it in.

I'll report back if the problem recurs again.

have you had anymore problems?

[packetfire]

From "frozencpu.com", I obtained:

vid-86 Swiftech MC21 Aluminum MOSFET Heatsinks - 21mm x 6mm x 10mm - 4 pack $9.95

vid-214 Alpha LPD25-10B Heatsink - 25mm x 25mm x 10mm - Anodized Black $3.00

thr-43 Akasa Thermal Adhesive Tape - 80 x 80 mm Square (AK-TT12-80) $4.99


The idea here is to use 2 of the 21mm x 6mm butted against each other to create a 21mm x 12mm heat sink for the flash chip on the CEM. I have an infra-red sensor thermometer, so I will be able to measure the surface temp of the chip without the heat sinks, and compare it to the surface temp of the heat sinks.

As the 25mm x 25mm heat sinks lack thermal adhesive tape, one must also buy the thermal adhesive tape. I looked at presumed "superior" adhesives, such as this one http://www.arcticsilver.com/arctic_s...l_adhesive.htm but they say that the bond is weaker at 0 C (32 F), so this does not seem to be a viable solution for a car that might sit in below-zero weather.

Does anyone have any idea of the chip sizes in the "REM" - "Rear Electronic Module", or photos of the bare circuit board? I have heard that they also need heat sinks, but I would rather not have to disassemble it until I have the heat sinks in hand.

[robert240]

Keep in mind Idaho gets up to 110 degrees Fahrenheit in the summer. Just installing the heatsink and leaving the metal lid off solved my problem 90% of the time, but I would like to install a fan next. I'm thinking about plugging it into one of the unused relay coil positions on the CEM so that it's powered only when the car is running, any suggestions?

[Boneslb9]

Keep in mind Idaho gets up to 110 degrees Fahrenheit in the summer. Just installing the heatsink and leaving the metal lid off solved my problem 90% of the time, but I would like to install a fan next. I'm thinking about plugging it into one of the unused relay coil positions on the CEM so that it's powered only when the car is running, any suggestions?

I just tapped mine to a fuse that gets power once the key is in the on position. No problems in 2 years.

[Forkster]

Ditto - I purchased a 12V 6" computer fan from a local tech store and positioned it over the entire CEM board. Before I sold my XC70, never had another issue with the CEM freaking out.

[AlexC]

Hello guys (I'm new to this forum and didn't take time to introduce myself, I'm sorry for that),

I'm also trying to add heatsink on my CEM (2004 XC90) since I had the same issues discribed by many of you.
A guy on youtube even recorded the exact same thing that happened to me : https://youtu.be/fMGvLQhU_Fw

Like Forkster I had hard time pulling out the CEM but his post helped me !

Now I'm trying to unplug it and it is very hard to pull off and I don't want to break anything.


What is the workflow to unplug it, are there things to unlock before or shall I just use more strengh and pull harder the screw ?

(Sorry for the poor english, I'm french.)