Early DME repair write-up with pics.
11-09-2006, 11:19 PM
#1
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Early DME repair write-up with pics.
Ok, searched everywhere and could not find a good solid set of directions and/or pictures for the early DME re-solder. We were having intermittent no-starts with my brother's car, my spare early DME (1983) did the same thing. I resoldered the whole upper board and the car is now 100%! So here is my contribution for the week:
Note - when I refer to the top or upper board, I am talking about the side with the Bosch sticker on it. The unit mounts upside down, thus the clarification.
Picture 1 - The top of the DME, part number - you can see the four screws, one in each corner that secure the cover. These are the ONLY screws that need to be removed for the repair.
Picture 2 - Not a whole lot to see here, just trying to show it from all angles.
Picture 3 - Bottom of the DME, this cover does not need to be removed for the repair - it is secured in an identical manner as the top cover.
Picture 4 - This is the backside of the bottom board where the "chips" are located. Since it is an early DME, the chips are soldered directly to the PCB rather than being socketed like the late. There really are not any high-amp connections on this board that require resoldering.
Picture 5 - The guts! You do not have to take it this far apart to perform the repair, I just wanted to show the contents. Both boards are secured to the housing by four screws, with a plastic stand-off in the middle that separates them. The four screws that hold the board are not the same! Take note of where the two different types go or refer back to these pictures if you forget.
Picture 6 - The topside of the bottom board, see the chips?
Picture 7 - Here are the components that are subject to cold solder decay. This is the board that requires repair.
Picture 8 - Ok, here's where we start working - remember, this is the only cover that NEEDS to be removed to perform the repair. Basically I just resoldered all of the accessable joints on this board - overkill - but I only wanted to do it once. I nice, hot, fin-tipped iron is required, as well as fine solder. I am not going into detail on the finer arts of soldering, plenty of info on the web - just take your time and do a nice job, making sure all the new joints come out shiny. Don't get sloppy and cross any joints that aren't supposed to be connected! You can tell which joints are the high-amperage ones - those are the most important, but I did all of them.
Picture 9 - Check me out - those are indeed my super-skilled fingers!
I hope this is beneficial - I know most people here are DIY (hence the write-up), but I am going to extend a service.......send me your DME and I will solder the whole upper board and mail it back to you for a flat $25.
Note - when I refer to the top or upper board, I am talking about the side with the Bosch sticker on it. The unit mounts upside down, thus the clarification.
Picture 1 - The top of the DME, part number - you can see the four screws, one in each corner that secure the cover. These are the ONLY screws that need to be removed for the repair.
Picture 2 - Not a whole lot to see here, just trying to show it from all angles.
Picture 3 - Bottom of the DME, this cover does not need to be removed for the repair - it is secured in an identical manner as the top cover.
Picture 4 - This is the backside of the bottom board where the "chips" are located. Since it is an early DME, the chips are soldered directly to the PCB rather than being socketed like the late. There really are not any high-amp connections on this board that require resoldering.
Picture 5 - The guts! You do not have to take it this far apart to perform the repair, I just wanted to show the contents. Both boards are secured to the housing by four screws, with a plastic stand-off in the middle that separates them. The four screws that hold the board are not the same! Take note of where the two different types go or refer back to these pictures if you forget.
Picture 6 - The topside of the bottom board, see the chips?
Picture 7 - Here are the components that are subject to cold solder decay. This is the board that requires repair.
Picture 8 - Ok, here's where we start working - remember, this is the only cover that NEEDS to be removed to perform the repair. Basically I just resoldered all of the accessable joints on this board - overkill - but I only wanted to do it once. I nice, hot, fin-tipped iron is required, as well as fine solder. I am not going into detail on the finer arts of soldering, plenty of info on the web - just take your time and do a nice job, making sure all the new joints come out shiny. Don't get sloppy and cross any joints that aren't supposed to be connected! You can tell which joints are the high-amperage ones - those are the most important, but I did all of them.
Picture 9 - Check me out - those are indeed my super-skilled fingers!
I hope this is beneficial - I know most people here are DIY (hence the write-up), but I am going to extend a service.......send me your DME and I will solder the whole upper board and mail it back to you for a flat $25.
11-10-2006, 09:26 AM
#4
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Excellent write up Sharky, thank you. I added a link to this thread on my 951 DME repair thread. Click Here for the 951 thread.
Were you able to identify which component had cracked solder joints?
Keep up the good work
Were you able to identify which component had cracked solder joints?
Keep up the good work
11-10-2006, 10:41 AM
#7
Drifting
Sharky47, Excellent work! As these cars age we need more fundamental instructions like these. I think you could do the 944 world a huge favour by submitting these instructions to Clarkes Garage for posting on that web site.
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11-11-2006, 09:11 PM
#8
Big thirst, Sore Thumbs
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Napoleon
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Napoleon
Hey Sharky.
Not that what you did won't work, obviously it does.
But it will be a lot easier/better if you remove the conformal coating that is on there.
Easy way to do it is to lay the board component side up, in a thin layer of acetone for a minute. Then scrub with a plastic brush. Comes off easy and makes soldering much easier.
For early cars re-soldering isn't a big deal. If you've got moisture up to the steering rack you've got bigger isues than a water damaged DME. For Late cars you should probably re-seal using any form of electrical coating purchased locally.
Not that what you did won't work, obviously it does.
But it will be a lot easier/better if you remove the conformal coating that is on there.
Easy way to do it is to lay the board component side up, in a thin layer of acetone for a minute. Then scrub with a plastic brush. Comes off easy and makes soldering much easier.
For early cars re-soldering isn't a big deal. If you've got moisture up to the steering rack you've got bigger isues than a water damaged DME. For Late cars you should probably re-seal using any form of electrical coating purchased locally.
05-19-2018, 02:18 PM
#9
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Still re soldering DMEs for $25?
I need my DME re soldered but am not good at soldering. If you're still providing this service send me the info. on where to send my DME and how to pay you. Thanks.
