Hello
I like to mess with/think I can fix things of many different applications, one of which being cars. I own a 1983 Porsche 944 and the other week it quit on me. I'll spare you the automotive details, but I have narrowed it down to the DME which is the main control module in the car. It is a nearly 40 year old computer and quite an interesting piece of electrical design if you ask me. The common problem with these is that over the years, the vibrations in the car will cause one or more solder joints to crack which causes the DME to not work. There is a small amount of information on the rennlist forums, which are a Porsche forum, about how to fix these. The general consensus is, if you can't find the cracked joint, just re-solder em all. I have spent the better part of a day looking for this cracked join with no luck and i'm about to get to soldering but I have a few questions about this process and figured this would be a good place to ask for help. I have some limited experience with soldering and have the necessary tools but some things about this board are puzzling. As you can see, certain joints are bridged with solder. Are these only when two leads share the same pad? I'm assuming the best solution is re-solder the same way I found it, but what is the real answer here? Is it okay to not bridge these joints? In addition, certain leads seem to not be soldered to the board at all. Also, there's a coating on these boards and I've heard someone say you can solder through it but others have said remove it with acetone, which I don't have and don't feel like getting unless I have to. Finally if there's anyone out there who might have ideas on narrowing down exactly what on this board is wrong, that would be very helpful. From what I understand, the lighter side, in the case is all analogue, with caps, resistors etc. while the other board is all digital containing all the IC's that are doing all the maths. I can't find any schematics for the 1983 DME unit although they exist for the later models, but do have some changes. Thanks in advanced for your help, and even if you can't, hopefully people on this forum will at least find this old tech interesting! Pictures should be attached below.
(This last image is just an example of bridged joints and unsoldered joints)
I like to mess with/think I can fix things of many different applications, one of which being cars. I own a 1983 Porsche 944 and the other week it quit on me. I'll spare you the automotive details, but I have narrowed it down to the DME which is the main control module in the car. It is a nearly 40 year old computer and quite an interesting piece of electrical design if you ask me. The common problem with these is that over the years, the vibrations in the car will cause one or more solder joints to crack which causes the DME to not work. There is a small amount of information on the rennlist forums, which are a Porsche forum, about how to fix these. The general consensus is, if you can't find the cracked joint, just re-solder em all. I have spent the better part of a day looking for this cracked join with no luck and i'm about to get to soldering but I have a few questions about this process and figured this would be a good place to ask for help. I have some limited experience with soldering and have the necessary tools but some things about this board are puzzling. As you can see, certain joints are bridged with solder. Are these only when two leads share the same pad? I'm assuming the best solution is re-solder the same way I found it, but what is the real answer here? Is it okay to not bridge these joints? In addition, certain leads seem to not be soldered to the board at all. Also, there's a coating on these boards and I've heard someone say you can solder through it but others have said remove it with acetone, which I don't have and don't feel like getting unless I have to. Finally if there's anyone out there who might have ideas on narrowing down exactly what on this board is wrong, that would be very helpful. From what I understand, the lighter side, in the case is all analogue, with caps, resistors etc. while the other board is all digital containing all the IC's that are doing all the maths. I can't find any schematics for the 1983 DME unit although they exist for the later models, but do have some changes. Thanks in advanced for your help, and even if you can't, hopefully people on this forum will at least find this old tech interesting! Pictures should be attached below.
(This last image is just an example of bridged joints and unsoldered joints)