Another fallen victim of leaking capacitors

[lil_Blue_Ford]

@holyford86 , do you have anything to add?

 

[alwaysFlOoReD]

I have an update: I had to repair two traces, replace three capacitors, and four resistors. I don't have the tantanum, and I need to conformal coat the areas where I removed it, so I'll do that later.
The truck started right up and runs like a top.

I am by no means an expert at board repair, so probably better ways to get this done.
I found it best to clip out the bad components, scratch with the fiberglass pen to remove conformal coating, solder mask, and corrosion. The electrolite gets under the conformal coats and solder mask and eats the copper away.
Flux the area and add new solder to melt the old solder, pull the legs out.
I used the needles to clean out the holes; solder wick would work too.
I used my ultrasonic cleaner with a mild solution of white vinegar to clean up as much of the mess as I could.

A tip: with a UV light, you can see where the electrolyte has leaked.
For the traces that were damaged, I used magnet wire to make the repairs. Coated the clean copper and the magnet wire repairs with UV-cure coating.
Make sure you use an ohm meter to verify your repairs. The vias can also be eaten away, and that's a tougher repair; that's when you have to run bodge wires to complete the circuit.

The resistor values were guessed, I decoded the best I could, and compared them to photos online. I hope they're right

My ECU is from a 93 4.0L Ranger, if that helps anyone. If I were not in a hurry to get everything running, I would have made a video.

I used

1. One 10uf 63v 105c capacitor (buy high-quality caps)
2. Two 47uf 16v 105c capacitors (buy high-quality caps)
3. Two 200-ohm 1/2w metal film resistors (just what I had on hand)
4. One 510-ohn 1/2w metal film resistor (just what I had on hand)
5. One 2k-ohm 1/4w metal film resistor (just what I had on hand)

Tools and supplies you might want

1. Solder Iron, of course
2. Solder
3. Solder wick and or stainless steel non-stick tin hollow core needle (Great for cleaning the throw holes out)
4. Lots of flux
5. conformal coating
6. magnet wire
7. Fiberglass Scratch Brush (works great for removing the solder mask, conformal coating, corrosion.
8. UV-cure solder mask.

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Please;
Pics of the tools
Pics of the supplies.
I'm a visual person. While I can read and understand, I do much better with pics.

 

[Shran]

Your repairs look great! I was pretty worried about some of the traces when I saw your first pics.

FYI to those reading this thread: The factory used ELECTROLYTIC capacitors in these, not tantalums. Tantalums usually looks like little brown cubes although they can be other shapes and they have a very long lifespan and usually never fail. Electrolytic caps, however, have a much shorter lifespan and look like what's pictured - little round metal cylinders.

I used to do a lot of electronics repair and replacing electrolytic caps with tantalums was the standard practice, you just have to match what you have, sometimes that gets bit complicated with the physical size of the parts.

 

[holyford86]

@holyford86 , do you have anything to add?

Nope, this is some nice and clean repair work here.

I will agree that we should do something to make into a tech article and also perhaps have a library of capacitor values within that article to make it easier for people to figure out what to get without cracking open the unit beforehand.

I've got one unit I just recapped and another that is going to need some trace repair in addition to the recap. In units this old it wouldn't be a bad idea to replace the caps as a preventative measure, because if they aren’t leaking yet, you don't have much time before they do.

A decade ago these pcms could be had for around 100 as a reman at most parts stores, now they're getting hard to find and are 375 and up from what I've seen, that being said, its now worth it to do these repairs. I think I spent 14 dollars on 10 caps each of the values I needed from digikey (4 bucks worth of parts and 10 to ship)

 

[pentode]

I used

1. One 10uf 63v 105c capacitor (buy high-quality caps)
2. Two 47uf 16v 105c capacitors (buy high-quality caps)
3. Two 200-ohm 1/2w metal film resistors (just what I had on hand)
4. One 510-ohn 1/2w metal film resistor (just what I had on hand)
5. One 2k-ohm 1/4w metal film resistor (just what I had on hand

Nice job with the repair. I'm sure you could see it better than I can in the pics but was that resistor next to the diode a 2k or a 1k? Looks like brown-black-red in the photo but maybe it was a red-black-red and it's just not showing up well. I guess if it's working I wouldn't worry about it.

 

[pentode]

Your repairs look great! I was pretty worried about some of the traces when I saw your first pics.

FYI to those reading this thread: The factory used ELECTROLYTIC capacitors in these, not tantalums. Tantalums usually looks like little brown cubes although they can be other shapes and they have a very long lifespan and usually never fail. Electrolytic caps, however, have a much shorter lifespan and look like what's pictured - little round metal cylinders.

I used to do a lot of electronics repair and replacing electrolytic caps with tantalums was the standard practice, you just have to match what you have, sometimes that gets bit complicated with the physical size of the parts.

As you know, the problem with tantalums is they tend to go bang when they fail, and they have a reputation for failing a bit unpredictably at times. They're supposedly more reliable now than 20-30 years ago though, and for that matter electrolytics are much much better, especially if you stick with a good brand like Panasonic, Rubycon, Elna, etc. And in this application, definitely spend the extra 5 cents and get the 125C automotive grade caps.
There's a much better range of film cap values available now too, so I sometimes opt for film in demanding situations as they're pretty stable and rugged.

Edit: oh and as I've said in other threads, I would avoid buying caps on eBay and AliExpress at all costs - stick with Digikey, Mouser, or your local electronics shop as the market is flooded with counterfeits

 

[Shran]

Electrolytics go bang too And they smell like dead fish...

I've had zero problems with SMD tantalums as long as they are not connected backwards. I would probably just stick with a good electrolytic cap in this particular situation though.

 

[pentode]

Agreed, and I'm not trying to take over the thread to have a capacitor debate.
What I probably should have said is that given that tantalums are sensitive to thermal shock (from soldering and from use) and other factors like ripple current etc, I would hesitate to recommend a beginner go swapping out electrolytics for tantalums - not saying you're advocating that, but just didn't want anyone to get the idea that would necessarily be an upgrade. If you understand the circuit and what the cap is doing in the circuit then by all means mod away! Sorry to be pedantic.

 

[lil_Blue_Ford]

Can I wish that RadioShack still existed? Lol

 

[RobbieD]

Can I wish that RadioShack still existed? Lol

Yes; that would be Realistic.

 

[lil_Blue_Ford]

Yes; that would be Realistic.

The local one when I lived at my parents old place got so fed up with me they gave me one of their catalogs… the one they ordered from… and told me to come back with part numbers, lol

 

[rumblecloud]

Yes; that would be Realistic.

I saw what you did there...

 

[pentode]

Can I wish that RadioShack still existed? Lol

Electronics as a hobby was so great in the 70s (and I'm sure the 50s and 60s too). We were almost spoiled for choice. You had Rat Shack and most cities of any size had amazing electronic surplus stores (anyone ever been to Addison in Montreal?) You had buckets and buckets of quality surplus parts, often military/government stuff for dirt cheap prices.
In this area here, the trade schools are phasing out electronics as a course of study and there are only 2 electronics repair shops for a town of 130,000, one of whom is 83 and been retiring for the last 4 years.
Aside from the maker community (God bless the makers) nobody really makes anything anymore, nobody fixes anything anymore largely because everything is disposable.
I know I exaggerate and it's ironic complaining here as you guys are the ones fixing stuff, so kudos to all of you who fix broken stuff. Also I'm nowhere as old as I sound but I probably am that cranky.

 

[lil_Blue_Ford]

Electronics as a hobby was so great in the 70s (and I'm sure the 50s and 60s too). We were almost spoiled for choice. You had Rat Shack and most cities of any size had amazing electronic surplus stores (anyone ever been to Addison in Montreal?) You had buckets and buckets of quality surplus parts, often military/government stuff for dirt cheap prices.
In this area here, the trade schools are phasing out electronics as a course of study and there are only 2 electronics repair shops for a town of 130,000, one of whom is 83 and been retiring for the last 4 years.
Aside from the maker community (God bless the makers) nobody really makes anything anymore, nobody fixes anything anymore largely because everything is disposable.
I know I exaggerate and it's ironic complaining here as you guys are the ones fixing stuff, so kudos to all of you who fix broken stuff. Also I'm nowhere as old as I sound but I probably am that cranky.

I think part of the problem was the move to surface mounted components and complicated small circuit boards that pretty much require you to have a hot air soldering system and magnifying glass instead of a $20 cheap soldering iron

 

[ronclark]

@ronclark Do you do repair work and what are your rates?

@rumblecloud board repairs just been hobby, I would not mind doing repairs. I would not to be put in a spot were the damage been repaired in the ecu, but the truck got something else wrong with it and get the blame that my work was no good you know? since i have no way to put in a working truck to verify my work

Please;
Pics of the tools
Pics of the supplies.
I'm a visual person. While I can read and understand, I do much better with pics.

@alwaysFlOoReD
if i have time this weekend ill get some photos and links to the tools i used.

i was going to replace the tantalum more as a preventive measure because working one vintage computers i seen way to many go short and bang, seems to be always the 12v rail.

if we can get are hands on schematics to add to the library, that would make some of theses repairs easier when you have damaged components we have to guess there value. so if anyone knows were to get there hands on some that would be great