Sensor TM1p SO-DIMM Proximity sensor location anyone?

Hi

I wonder if anyone here has an idea if this sensor problem can be rectified. I have recently acquired an iMac 27 late 2013 that had an LCD failure and Apple quoted £350+ to replace after being with them to diagnose. I bought an LCD of ebay and replaced it but system seemed slow so I ran ASD and it came out with 3 errors from which the LCD sensor and HDD are now solved but remains the TM1p So-DIMM 2 proximity board temp sensor which for the life of me I cannot identify. The service manual isn't helpful at all as it suggests to replace the motherboard which I doubt that this cannot be fixed. I have tried to get hold of the schematics for the imac but I can't find it anywhere for free.

If anyone here can point me in the right direction I will be eternal grateful. I have attached photos of the errors

Specs:
iMac 27 late 2013
i5 3.2GHz
16GB Ram
1GB VRAM
250SSD
OS X Yosemite
Board 820-3478-A

I think you should move the RAM DIMMs around and see if the error follows ... I think the sensor error is on the RAM. Just guessing.

Is there heat sensor for the internal drive? And that was not set up properly?

Agree with gsahli. That RAM related temp issue is probably due to bad RAM. Other long shot possibilites are:

- Maybe the RAM needs to be removed & reinstalled making sure it's seated properly.
- Maybe there is debris in one or more of the RAM slots (blow out with canned compressed air).
- Maybe one of the RAM slots is bad (does happen).

I would do as gsahli mentioned. Move the RAM around & see if the issue persists or "moves" in the report. Or remove all the RAM...then only reinstall the minimum amount...and see if the error goes away. And if not...keep swapping out the RAM until all modules are tested by trial & error.

HTH,

- Nick

Thanks for the replies but still no joy. I have tried with 10 different ram modules in all 4 slots. The outcome is the same on Dimm 2. I wouldn't mind if a slot would be bad but it takes 64-70% of the cpu. The fan I control it with Macs Fan Control App which reports the temperatures but Dimm 2 isn't on the list

A couple of more pics. I also pulled the motherboard out and inspected it and there is nothing that I can see to be missing or anything hence I asked if someone has a schematic and can tell me the location of the sensors. Googling part numbers isn't turning any results

Did you test one stick of memory at a time? In each slot?

Yes I did

Apple schematics and service manuals are proprietary and kept pretty much locked up like atomic secrets. Whatever you can glean from www.ifixit.com is about all we can suggest, otherwise you'll be battling windmills.

chscag said:

Apple schematics and service manuals are proprietary and kept pretty much locked up like atomic secrets. Whatever you can glean from www.ifixit.com is about all we can suggest, otherwise you'll be battling windmills.

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I have the service manual which says to replace motherboard on this error but I really doubt that this can't be repaired

If you tried one stick in each slot and still got the same message, I would say the sensor is defective/damaged.

Oh, I suspect it CAN be repaired, but the cost would be prohibitive, even if you could get the part. Thus, the service manual says to replace the motherboard because that is the much more efficient and less costly approach. These days the entire board could be manufactured for the time it would take a skilled laborer to remove and replace a component on that board. That's just how things work today.

You are on a search that is extremely unlikely to find anything. Get a replacement motherboard and move on.

MacInWin said:

Oh, I suspect it CAN be repaired, but the cost would be prohibitive, even if you could get the part. Thus, the service manual says to replace the motherboard because that is the much more efficient and less costly approach. These days the entire board could be manufactured for the time it would take a skilled laborer to remove and replace a component on that board. That's just how things work today.

You are on a search that is extremely unlikely to find anything. Get a replacement motherboard and move on.

Click to expand...

Well, it might be cost effective for you to buy a new motherboard since it seems that you have the money but I don't have £300/$450 just lying around. I posted on here for help not to be told to just replace it. If I had the money, I would have bought it and not bothered to post in here just so I can read someone's sarcastic comments.

Apple might be paying a few bucks for the boards to be made but the end user pays through the roof for 1. Schematics for an electronic component are drawn so it can assist with the repair of the said component otherwise they will be just useless.

My question is very simple. Has anyone got a schematic for an Imac 27 late 2013 and can point me in the right direction of the sensor or mail me the schematic and I will find it myself and then decide whether or not it is cost effective to repair or replace.

Thank you and helpful comments an/or constructive criticism it is much appreciated

Yes, Apple has the schematics. Contact them and offer them, how much you believe their development, of the iMac, is worth to them.

udowsky said:

Well, it might be cost effective for you to buy a new motherboard since it seems that you have the money but I don't have £300/$450 just lying around. I posted on here for help not to be told to just replace it. If I had the money, I would have bought it and not bothered to post in here just so I can read someone's sarcastic comments.

Apple might be paying a few bucks for the boards to be made but the end user pays through the roof for 1. Schematics for an electronic component are drawn so it can assist with the repair of the said component otherwise they will be just useless.

My question is very simple. Has anyone got a schematic for an Imac 27 late 2013 and can point me in the right direction of the sensor or mail me the schematic and I will find it myself and then decide whether or not it is cost effective to repair or replace.

Thank you and helpful comments an/or constructive criticism it is much appreciated

Click to expand...

udowsky, I didn't mean my comments to be sarcastic, but serious. Sorry you misunderstood.

However, I think you missed my point. IF you can get the schematics (highly unlikely given how Apple protects their intellectual property) and IF you can get the part (also unlikely, but maybe some warehouser of electronic parts might have one, otherwise you would have to buy in bulk from the component manufacturer) and IF you have the equipment to do reflow soldering and/or surface mount component soldering (that alone is pretty expensive equipment, well above the price of a new motherboard), you would still need to enlist the services of someone who knows how to do reflow soldering. And those people don't come cheap.

And that's why it is going to be cheaper for you to just save your pence until you can spend that £300 for a replacement motherboard. Unless you own a reflow soldering system already, of course, which you have not mentioned before.

Sadly, today's electronics world is not for the average guy with a soldering iron any more. I used to assemble electronics myself, but don't anymore because of the increasingly tiny size, surface mounted components and reflow soldering.

My question is very simple. Has anyone got a schematic for an Imac 27 late 2013 and can point me in the right direction of the sensor or mail me the schematic and I will find it myself and then decide whether or not it is cost effective to repair or replace.

Click to expand...

You've already been told that Apple schematics are proprietary. If you really wish to pursue this, then we suggest you contact Apple and ask them to supply you with a copy of the schematic you need. And of course we fully understand that you will decide if the repair is cost effective or not. As for any parts you need, eBay is always a good place to shop around.

One question for you.. you stated that you have an Apple Service Manual. Doesn't their official service manuals include schematics? I thought they did?

For anyone else who is wondering where the ram sensors are located, they are located under the plastic cage surrounding the ram. In my case, one of them was broken. There are two on each side, one for each so-dimm slot located under a capacitor.

Has the label of 3S on it. As far as I can tell, the 3S represents a NPN transistor. Used a MMBT3904 and it now I have a sensor reading for dim 2 slot. And now fan doesnt ramp to max and i am not locked to 800mhz

This was on a imac 27" late 2013

Whoustatich said:

For anyone else who is wondering where the ram sensors are located, they are located under the plastic cage surrounding the ram. In my case, one of them was broken. There are two on each side, one for each so-dimm slot located under a capacitor.

Has the label of 3S on it. As far as I can tell, the 3S represents a NPN transistor. Used a MMBT3904 and it now I have a sensor reading for dim 2 slot. And now fan doesnt ramp to max and i am not locked to 800mhz

This was on a imac 27" late 2013

Click to expand...

The MMBT3904 seems to be way too big of a package size, unless these come in multiple sizes? I tried a different transistor of similar specs that fits the pads but it’s still not reading the sensor. Where did you order yours from?

Edit: Never mind, looks to be the MMBT3904LP-7 which is the correct package size. Looks to have the same electrical characteristics of the one I bought though, I'll recheck my soldering.