Possibility of Saab closure

I plan to open up my old one...... when I get my car back. I want to see whats inside. After all, I've been in the electronics repair business for

Are you interested in taking digital pictures of it? I'd be delighted to post them if you don't have a place to do so.

Dave Hinz

Salutations:

How do you remove the epoxy without destroying the wiring and circuit boards it's pooled over? Curious spare DI owners want to know..

When we are doing our failure analyses at work, we first x-ray the part. Then we (I do not do the actual work) soak the epoxies part in heated Uresolve(r) or Megasolve(r), cocktails of solvents. After an hour or so it softens up the epoxy and you can pull it away.

Those solvents are probably unavailable to the home mechanic. But maybe a mixture of paint thinner and other solvents will work over a longer time.

Stephen B

Very interesting. So, if I understand the next logical step - you can in theory end up with a stack of individual coils and whatever mysterious supporting electronics make up the $800 Canadian part? You know, all open in front of you such that you could review the components and repair rather than toss the whole thing and buy yet another round?

I wonder if the cocktail peels the transformer part numbers and circuit silkscreening. I just happen to have a spare DI unit as of this afternoon.

With a BS response like that. I don't feel good at all. My first Saab was in 1980 and I think my last was in 2003. Damn I hate to say that.

Sorry to hear you acquiring a spare unit (assuming a failure).

From the blocks I have seen, you may luck out and be able to read the numbers, but I would not count on it. Our epoxy and I think most manufactures of electronic blocks use various fillers to improve heat transfer and dielectric resistance. The solution does not seem to effect the filler, but dissolves the epoxy leaving the filler which can be broken away. These are some dangers you should be aware of.

The part numbers could be printed in epoxy ink, and gets dissolved. The structure of the inner components are frequently epoxy also and damaged. these chemicals can also eat away at the solder joints and other unexpected places.

I would definitely suggest trying to get an x-ray first so you have some idea what is inside. at which time you could probably cut the unit down and just open up one unit. If you want to contact me off line and send the unit to me, I should be able to arrange to do all of this and send you the pictures and remains.

Stephen

I'd expect that there are mechanical supports in there as well, not just the whle thing held together with structural epoxy.

Quite possibly, but you have to consider the costs. Labor, chemicals, hazmat disposal of used "cocktail", that sort of thing. Not so bad for a home experiment, but hard to make money at it as a business I would think..

The commercial ones are probably label-safe and specific to epoxies. Home-grown, probably not so much. But it'd be fascinating to see results of that experiment.

Dave Hinz

Salutations:

Hey brother Dave - not a home business, but perhaps a livable alternative for the long-term 9000 owner like myself. Once it was stripped down, I'm wondering if I can't then just replace the coils and transformers as needed rather than springing for the whole banana each time.

I was reading somewhere before Christmas that 80% of the time they have simply cooked a coil.

Hey - on another line - what do you know about MAP units on the 93 AERO?

I've done the DI, the alternator, the O2 sensor, the over-boost valve (replaced with a very nice Audi unit actually) - and I still have a slightly rough idle, still feels light in the horse-power department and still gets an occasional hick-cup on normal, cold acceleration... ARGGGG...

Based on the blocks we make (bridge-rectifier and diodes) the components are frequently mounted on a fiberglass board and then potted in the epoxy. But if the stiff enough we will just mount to the terminals (which are screwed in place in the mold) and pot around them.

I doubt using chemical stripers to repair would work in a repairing situation. I am not talking about aplying the paint striping paste type of operation. Picture puting a 2"x3"x1" block in large beaker filled with solvents. you just can't control the location well enough.

Stephen B NYC

Reading the part numbers and labels depends on the care and patience used in watching the chemicals, as well as the ink used. I see more likely it would be useful as a reverse engineering project that would allow the making of individual coil systems.

Being new to SAABs, I have not dug into my engine bay to try and locate mine. Do you have a picture and dimensions on these things? Would making 4 separate blocks that could share the input make sense and fit?

Stephen B

I guess it depends on the failure mode(s) seen. If you can mix&match and make good ones, sure. If it's always (blah) that always fails, then not so much.

I wonder what percentage of them have cooked a coil _after_ Christmas? (sorry, just playin')

Not a thing.

Dave Hinz

I once opened a faulty DI from my otherwise excellent 9000 CSE. The DI was stuffed with black gooey. Any potential repair will have to withstand the high temperatures and vibrations and the coils will have to be exactly matched. Not likely to succeed IMO.