Testing MS3 Pro (module) Idle valve outputs?

[B1ack_Mi16]

I'm running a stepper motor and it has worked just fine until now.

Started engine today and it idled at 2000rpms. Always went down to about 1200rpm cold and 1000rpm warm before.

I tried changing the valve itself, but to no use, it is totally dead. I would guess wiring error is also not very likely, as it would still probably go in or out if there is one broken wire (of 4). As the spare valve I fitted was quite a bit extended and the orginal one was retracted I think it can't be the wiring as one of them at least should've moved either in or out. If not more than 1 wire is broken at the same time, which seem unlikely as the car has just been in the garage all the time.

Is there any way of testing the stepper motor output ports from the MS3 Pro?

I've got no clue where to continue now, apart from purchasing a new MS3 Pro module? But that seem a bit expensive...

[nathaninwa]

You can turn the iac wires into programmable inputs and outputs and test. One will be 12v the other will be ground on each pairs of wires

[billr]

Those 4-wire steppers absolutely do require all four wires to move!

Checking the motor itself is quite simple, though, if you want to be sure it (they) are OK. With stepper disconnected, measure resistance between all combos of the four pins. Two pairs should have the same resistance between them (probably about 50-55 ohms) and the two "pairs" should have no continuity to each other. No pins should have continuity to the stepper case (ground)

[B1ack_Mi16]

Ok, I'll do some Ohm'ing of the wiring and see if I can activate the outputs manually to see whether there is any response or not.

Is it a hard job to change the chip itself? I see it seem to be quite small, so maybe it's not suitable just using a soldering iron on my workbench?
I suppose I can use these for replacement?

http://au.rs-online.com/web/p/motor-dri ... /7532034P/

[jsmcortina]

Use the I/O test modes to check operation of the outputs.

Changing the chip depends on your skillset. There are lots of training videos of youtube of SMD repairs, study first.

I use cooking foil to mask off surrounding areas and then a hot air gun to gradually heat the chip until I can remove with tweezers. Pre-heat with the gun at ~200mm for a minute, then move a lot closer.

James

[B1ack_Mi16]

Thanks. Will go and try very soon now.

Btw. I see in my link it is the A4970SLBT chip I linked to, but I suppose the one to use is called A4970GLBT.
But the latter one I can't seem to find for sale on the internet. Anyone got a clue, or a link, or something relevant?

[billr]

Are you in Europe? It looks like the "G" is readily available in the USA, but not Europe. The difference between the two is the range of ambient temperature they can work in. If your MS is going to be in the cabin, not "underhood", then the "S" should be fine.

Regardless, I wouldn't jump into changing that chip until you are sure it is bad. They aren't all that easy to change; and are "robust" enough that I think it is more likely you have a wiring problem than a bad A4970 chip. This being a Pro, have you contacted DIY about warranty?

[B1ack_Mi16]

Thanks for input. I've tried to check the wiring today and it seem to be fine. (I've not moved the car out of the garage since it worked some days ago, so it must have happened suddenly and car is stationary and has never been driven or moved during this period).

Also tried to activate the stepper outputs but no voltage at any of the pins, so it seem to really be "dead".

I found out that the S probably can be used instead so placed an order on a Norwegian branch of a international electronics deliverer for 3 x A4970 "S".

It is not placed in cabin, but it is at least located behind the firewall to the side, so I don't think the temperatures will get that high there.
Although the temps could possibly go below -20C as there are occationally -30C.. not that I think I'll be using this car at those temps anyway.

Can one not just get a very tiny pliers like this?
http://www.ebay.com/itm/Durable-Diagona ... Sw-itXu57L

And somehow cut off the existing chip.. then use a regular soldering iron to remove the rest of it that is attached to the board?

The new chip can then be soldered on pin by pin I would suppose, or is this not likely to work?

[billr]

Cutting an SMD component, so that the leads can be removed one-by-one, is a method I often use. If you can nip each lead, great. Or, use a small abrasive disk, like on a Dremel grinder, to cut away the old device. Point is, you don't want to be putting any mechanical load on the leads, like prying at the SMD body. Soldering the leads one-by-one works fine. Find some small-diameter solder, like .015", to make it easier.

[B1ack_Mi16]

Ok. Actually got offered an RMA from DIYAutotune today, good service.

However I think I'll have a go at fixing it myself now as the chips are arriving tomorrow evening by DHL Express.

Managed to get the chip off today quite easily with some small pliers and the soldering iron. Hope nothing took damage in the process.

[billr]

It looks like the leads from the IC are still on the PCB pads. I would clean them off, using solder-wick. You want the "gull wing" leads of the new IC to all sit as flat as possible to the pads; that will minimize how much you have to heat the pads/IC to install the new one. I always smear a thin film of rosin flux on the pads before setting the IC down. It kind of "glues" the IC from slipping, and ensures easy soldering

[B1ack_Mi16]

If you mean the left-overs of the pins from the old chip they were removed indeed even on the picture.

I don't have much soldering equipment, but managed to get the new chip soldered in today, probably not in the most professional looking way.

But it is securely attached and the stepper motor now moves perfectly fine again, so thanks for your help

[jsmcortina]

Good work!

Double check that all ground pins are connected correctly. I believe that has been blamed as the cause of some stepper drivers in the past.

James